Digital Camera Buyer’s Guide — Choose the Best Camera
Table of Contents
Complete series
Click for complete series
Introduction
Overview
First, congratulations! Camera technology has advanced so much that a complete novice using an entry-level camera straight out of the box can take photos that, in many situations, look as good as professional images.
Key principle
Regardless of whether you only use your camera in automatic mode or you explore the art of photography, the most important part of any photograph is you — your brain and your eyes. To paraphrase: cameras don’t take good pictures, people do. So, to the question of “what camera should I buy?” —
Who this guide is for
It depends. The best camera for you is the camera that meets your needs. While Physics Forums (PF) cannot recommend a single model (for various reasons), we can provide the technical background to help you interpret product reviews and make a rational choice. This sticky is organized by experience level — from zero to expert — and revisits certain topics because imaging requires trade-offs that stem from the underlying physics. PF has a dedicated group of enthusiasts who are happy to help you take better pictures.
Preliminaries and definitions
Terminology
Some quick definitions used throughout this guide:
- Lens: the glass or plastic assembly at the front of a camera, often composed of multiple elements and rotationally symmetric about the optical axis.
- Sensor: the light-detecting chip inside a digital camera.
- Imaging: the same as taking a picture.
- 35mm format: the standard 135-film camera format (Kodak 135). The frame is 36 mm × 24 mm, with a diagonal of about 43 mm; much camera nomenclature derives from this format.
Table of contents
How to use this guide
Each section below corresponds to a general class of photographer (that is, you). The topic lists show the concepts you need to understand to make a rational camera purchase.
Beginner — “I’ve never owned a camera (beyond my phone)”
Beginner overview
Use case: I want to take pictures at parties, post them online, or email them to friends.
Common beginner terms
Basic Definitions
- What’s so special about digital cameras?
- Half-press (autofocus/shutter activation)
- Bayer filter
- Flash
- Gain (ISO amplification)
- Dynamic range
- Optical vs. digital zoom
- White balance
- Live preview
- Image stabilization
- Shooting modes (auto, program, aperture priority, etc.)
- Video
Intermediate — “I want a real camera or to improve beyond an entry-level model”
Intermediate overview
Use case: I’ve owned an entry-level camera and want to take the next step.
Key concepts
- Focal length
- f-stop (aperture)
- Exposure time (shutter speed)
- Resolution (megapixels) and perceived sharpness
- Crop factor (sensor size effects)
- Depth of field
- ISO and noise
- Exposure bracketing
- Frame rate (continuous shooting)
- Histogram (exposure analysis)
- Post-processing basics
- Pixel size and sensor performance
- Macro imaging
- Autofocus systems
- Sharpness and resolving power
- Memory cards and write speed
Advanced — “I’m ready for a DSLR or mirrorless system”
Advanced overview
- Lens classifications (prime, zoom, wide, tele)
- Lens aberrations (chromatic, spherical, etc.)
- Falloff (vignetting)
- Flare
- Bokeh (out-of-focus rendering)
- Image stabilization systems (in-lens vs sensor-shift)
- Filters (UV, polarizer, ND)
- Sunny 16 / Rule of 16
- Hyperfocal distance
- Focal, principal, and nodal points
- Miscellany and advanced topics
Next installment
Look for Part 2 coming in the next few days!
PhD Physics – Associate Professor
Department of Physics, Cleveland State University
[QUOTE="DaveC426913, post: 5575814, member: 15808"]This is surely outside the scope of this article, but I am interested to see if taking RAW format pics is of any benefit to me. I've taken some test photos in the 'JPG and RAW' mode, and used RAW image software, but frankly I can't see much I would do to the RAW image – at least, nothing that isn't otherwise doable in PhotoShop. The compression that comes wth JPG images does not seem to be mitigated noticeably in a RAW image.” I consider that a personal choice. For me, I simply can't handle the workflow required to manage routine RAW images. JPG works for me, except for astrophotography.
[QUOTE="Greg Bernhardt, post: 5575338, member: 1"]Looking forward to the rest of the series! One question though. With the meteoric rise in smartphone cameras, is the quick shot camera near death? I believe the only advantage at the moment is a bit of zoom?” I think you may be right- modern smartphone cameras (2016) perform as well as DSLRs from (IIRC) 2007. One area where inexpensive dedicated cameras have an advantage is the sensor size: larger fields of view, more sensitive pixels, etc.
I am looking forward to the continued insight articles! It is a topic I am very interested in…
[QUOTE="davenn, post: 5575889, member: 283516"]until you start doing serious editing then you quickly find out the problems assoc. with JPG's :wink:”Maybe that's the issue. I have a little G15, not a DSLR, so it may not leverage the power of RAW.
[QUOTE="davenn, post: 5575889, member: 283516"]I primarily only shoot in RAW. it has the huge advantage of being able to push the image much further than in JPG …. much, much further”Just make sure you have a huge memory card :)
[QUOTE="DaveC426913, post: 5575814, member: 15808"]This is surely outside the scope of this article, but I am interested to see if taking RAW format pics is of any benefit to me. …..” A sunset over daffodils. Left: out of camera jpg. Right: heavy post-processed RAW
[QUOTE="Greg Bernhardt, post: 5575338, member: 1"]Looking forward to the rest of the series! One question though. With the meteoric rise in smartphone cameras, is the quick shot camera near death? I believe the only advantage at the moment is a bit of zoom?”great question, Greg.Smartphone cameras have come a long way in the last 5 years. big jumps in megapix count and overall image quality.And yes there are now even addon lenses for them, one example .. http://www.digitalcamerawarehouse.com.au/prod11943.htmnot brilliant, but it does extend the capabilitiesand the general consensus is that they are considerably damaging point and shoot sales figuresfrom wiki”According to the NPD Group, up to end of November 2011 point-and-shoot cameras took 44 percent of photos, down from 52 percent in 2010, while camera-equipped smartphones took 27 percent of photos in 2011, up from 17 percent. Unit total sales of all types of point-and-shoot cameras declined by 17 percent year on year, but increased by 16 percent for cameras having optical zoom greater than 10x.[6] At the end of 2012, more than one brand have released point-and-shoot cameras with 24x optical superzoom[7] as compensation of sales decline and at the end of 2013 there were 30x optical point-and-shoot cameras.P&S camera sales dropped by about 40 percent in year 2013 particularly inexpensive cameras, so Fujifilm and Olympus have stopped development of low-end P&S cameras and focused to develop mid and high-end cameras with more added value”Smartphone photography is also hurting DSLR sales as wellFrom DPReview, my favourite camera review site … https://www.dpreview.com/articles/5928296460/canon-q4-earnings-report-shows-camera-sales-are-down“Canon has released its 2014 Q4 financial report, showing an overall profit increase but a continued slump in camera sales. Canon saw its quarterly operating profit – which spans from the three months leading up to December 31 – rise 5.4% year-on-year to the equivalent of $835 million (98.5 billion yen).Despite the increase, it failed to meet analysts' expectations. Canon's imaging business saw its operating profit fall 6.2% year-on-year, with a 58.3 billion yen operating profit. Sales in that segment fell by 7.3% YOY. By region, the biggest decline in sales came from the Americas, down 11.9% from 2013. Smartphones are cited as a big cause for the slowdown in camera sales. In 2015, the maker anticipates its compact camera sales will only hit 7.8 million units, which is a substantial decrease from 2014's 9.03 million, and predicts interchangeable lens camera sales will remain relatively flat at 6.4 million units. Still, Canon expects that this year will prove favorable as far as sales go, with the company estimating it'll bring in 3.9 trillion yen, a year-on-year increase of 4.6-percent.”DSLR's will always be there for the serious amateur and professional photographers.There's an old saying … " Everyone thinks they are a photographer until the take the camera from Auto to Manual mode"And there-in lies the huge advantages of DSLR's ( or the old SLR film camera) … you can get full control over the camera in every aspect.almost nothing like that can be done with a smartphone camera, extremely limited. Point and Shoot cameras are much better but still have a lot of limitations.And even DSLR's have come a very long way since [USER=20368]@Andy Resnick[/USER] first penned this insight article.Huge leaps in lens quality, megapix count, high ISO noise control, faster focussing, image stabilised lenses, better metering to name some of them.I'll stop waffling for now :wink:Dave
[QUOTE="DaveC426913, post: 5575814, member: 15808"]This is surely outside the scope of this article, but I am interested to see if taking RAW format pics is of any benefit to me. I've taken some test photos in the 'JPG and RAW' mode, and used RAW image software, but frankly I can't see much I would do to the RAW image – at least, nothing that isn't otherwise doable in PhotoShop. The compression that comes wth JPG images does not seem to be mitigated noticeably in a RAW image.”I primarily only shoot in RAW. it has the huge advantage of being able to push the image much further than in JPG …. much, much further”The compression that comes wth JPG images does not seem to be mitigated noticeably in a RAW image”until you start doing serious editing then you quickly find out the problems assoc. with JPG's :wink:Dave
This is surely outside the scope of this article, but I am interested to see if taking RAW format pics is of any benefit to me. I've taken some test photos in the 'JPG and RAW' mode, and used RAW image software, but frankly I can't see much I would do to the RAW image – at least, nothing that isn't otherwise doable in PhotoShop. The compression that comes wth JPG images does not seem to be mitigated noticeably in a RAW image.
I think this may be the very first PF Insights I've ever followed.Write faster please.
[quote="Topher925, post: 3522550"]What is everyone's opinion of the Sony SLT A65 & 77 being released next month? …. Whichever camera I buy a lot of its time will be spent doing some lite astrophotography so high noise is a big concern.”Here are more answers, dpreview has made test shots available with the A77. So if you go to any test, like this of the Canon 60D then you can compare crops of many cameras on this page (in RAW).In the individual drop down menus you can select available cameras (I selected Sony A77, Nikon D5100, and Canon 5D mkII) you can also select ISO and the crop to compare.
Tripods:A tripod holds a camera still while the shutter is open, preventing motion blur. The tripod must be able to maintain this stability in the presence of uneven ground, wind, ground vibrations, etc. Generally, tripods are most easily characterized in terms of the size (weight and height) and maximum load it can support. Usually, heavier tripods are more stable and can support more weight than lighter tripods, but lighter tripods may be more suitable for backpacking or other situations where excessive weight is a concern. At the extreme, monopods and small 'tabletop" tripods can be used when minimizing weight and volume is the most important consideration.There are three parts to a tripod: the legs, the head, and the camera/lens mounting plate. Many tripods also have a 'center column' that can be used to raise the camera above the legs. The overall stability of a tripod is a function of the legs, while control of the orientation of the camera is provided by the head. The height of the camera is controlled both by the legs and center column. "all in one" tripods consist of legs, head, and mounting plate integrated into a single device. Legs generally consist of 3 or 4 telescoping tubes, and the most important properties are 1) the maximum diameter of the tube, 2) the number of leg segments, and 3) the construction material, The larger the diameter and fewer the number of segments, the more stable the tripod. Legs can either be opened to only a specific angle or can independently open to several angles, but it's important to note that varying the leg angle only varies the camera height, not the tripod stability. Legs are typically aluminium, but carbon fiber can be used to provide additional benefits (vibration reduction, reduced weight, thermal insulation). Wood is also sometimes used. Telescoping segments are useful to both provide flexibility in camera height as well as correct for uneven terrain (for example, if the tripod is located on an inclined surface).A center column allows for easier fine control of the height of the camera. Because the column introduces additional vibrational modes, for maximum stability the center column should not be raised. Additionally, the presence of a center column limits the *minimum* height achievable for tripods that allow legs to fully open- a feature that can be useful if the camera must be located near the floor or ground. A second benefit of tripods with no center column is the ability to orient the direction of view to vertical, by swinging the front leg of the tripod underneath and behind the head.The head provides a mechanism to control the direction of view. Two classes of mechanisms- pan head and ball head- pivot the camera about a point below the optical axis of the camera, while a third class- gimbaled heads- pivot the camera about the center of mass, which provides additional stability when using heavy cameras. Pan heads provide separate control over each of the orthogonal rotation axes, while ball heads have a single mechanism (a captive ball and socket), which provides omnidirectional control. For both pan and ball mechanisms, the control and overall stability decrease as the lever arm between the center of mass of the camera and the point of rotation moves away from vertical. Often, ball heads will provide a "90 degree index" , which is a slot machined into the socket allowing either portrait orientation or vertical orientation, but the stability of the tripod is minimized and use of this index is not recommended. Because of this, it is generally recommended that "L-plates" be used for mounting the camera in portrait orientation. Gimbal mounts do not allow for rotation about the optical axis, although integrated lens mounts generally allow for this motion. Finally, there are several head attachments available for specialized operations: panoramic shooting sometimes requires precise camera rotation about the "no parallax" point, and macro shooting requires precise control over the object distance, and so translation and rotation stages are available which provide this specific control.The mounting plate can either be a simple 1/4" threaded post on the head into which the camera or lens directly attaches, or can consist of a "quick release plate". Quick release plates provide an added measure of security/safety when attaching or removing a camera due to the simplified process of attachment. The mounting plate is first attached to the camera or lens, and the mounting plate is placed on the head and clamped into place. Individual manufacturers can make their own plates, or plates can be made in a "Arca type" or "Arca-Swiss" plate geometry which is considered a standard.
I'm ready for a DSLR! A: These cameras were originally designed for professionals. Users of these cameras are expected to already understand basic digital photography techniques, and the in-camera electronic imaging processing should be viewed as enhancing good technique, not compensating poor technique. One key distinction between a DSLR and bridge camera is that the lens is removable on a DSLR. The lens performance is more critical now- a high quality lens will continue to deliver excellent performance long after the camera body is obsolete. A second key distinction is the sensor size- sensors in DSLRs approach or even exceed the 35mm format- there are some digital medium-format cameras on the market. A DSLR and well-corrected lens, based on over 100 years of continuously improved optical design, can approach the limit of what is physically possible. So in this section, we will present some additional details of imaging theory. Just as the case with film cameras, each manufacturer has their own proprietary 'lens mount' which can make switching between manufacturers problematic, if you have already spent money on a good lens. These include the Nikon F-mount, Pentax K-mount, Leica M mount, and Canon EF mount. Lag times in DSLRs are generally nonexistent.Classification of lenses: Lenses are classified based on their 35mm equivalent rear focal lengths. The standard lens is a 50mm lens; on a 35mm format, a 50mm lens produces an image that nearly matches normal vision in both magnification and field of view. Lenses with a shorter focal length are 'wide angle' lenses, until you get down to 10mm or less; these are 'fisheye' lenses and produce images with fields of view sometimes exceeding 180 degrees (a full hemisphere). Lenses between 70mm and 90 mm are usually referred to as 'portrait' lenses, while longer length lenses are 'telephoto' lenses that at the extreme end (1200mm and up) appear indistinguishable from telescopes. Zoom lenses have become more common, and involve complex movement of lens elements to allow changes in the focal length while keeping the focus (largely) unchanged. The standard 'kit' lens offered with a DSLR is usually a zoom lens; you do not *have* to get this lens with your camera. Tilt-shift lenses (or 'Perspective control' lenses) allow you to orient the lens with respect to the sensor plane- the effect is to remove perspective from a tall building, for example. This also allows imaging under the Scheimpflug condition, where the plane of best focus is not parallel to the sensor plane (useful for photographing hillside landscapes, for example). Macro lenses are designed for close-up focus and reproduction ratios approaching or exceeding 1:1.Just as the focal length of a lens is unrelated to the distance to focus, the rear focal length is not related to the distance between the lens and the sensor. Wide angle lenses, in particular "retrofocus type" designs, set the distance between the rear element and sensor to be larger than the rear focal length- the rear focal plane is located in the space between the rear element and sensor. This is to be compared to 'telephoto' lenses that place the rear focal plane out in front of the front element.Something to consider as well, is if the camera can be operated with *no* lens attached. This will give you additional flexibility in choice of lenses- but then you most likely have to work in 'full manual' mode.Everyone has their own opinions about what lens (or lenses) are 'the best'. Lens performance is critical here, and time spent doing research to get the best possible lens you can afford will result in a lens you will be very happy with for a long time.Lens aberrations: This is also a large subject, so only a brief synopsis will be presented here.Aberrations occur because the paraxial condition fails- that is, sin(q) != q. The paraxial approximation is very accurate for small angles: the error is 0.02% at f/5, and only 3% at f1.3. The next term in the expansion (sin(q)^3/3!) is the dominant error term, and represents '3rd order aberrations', "Seidel aberrations", or 'primary aberrations'. Each primary aberration (piston, tilt, defocus, distortion, coma, field curvature, astigmatism, and spherical) represents a independent deviation of the aberrated wavefront with respect to a reference sphere. These deviations are:Piston is a constant shift in the wavefront phase. Tilt is a (spatial) linear shift in wavefront phase. Neither piston nor tilt affect image quality, and are usually neglected. Similarly, we will pass over defocus, as camera lenses can adjust the focus.Distortion- Distortion is defined as the variation of magnification with image height. Straight lines do not remain straight; barrel distortion is positive, and lines bow out. The opposite is pincushion distortion. Distortion can vary with focus distance and is very noticeable: you can detect 0.5% distortion easily. This is often a dominant aberration in camera lenses, because in contrast to the other primary aberrations, the amount of distortion does not vary with aperture size. Fisheye lenses (intentionally) have distortions typically approaching 100%. Landscape and architectural photography in particular are very unforgiving of distortion.Coma- Coma is defined as variation of magnification with aperture: rays crossing the aperture plane at different heights cross the image plane at different heights. Points appear as small 'comet' shaped blobs (hence the name). This is particularly distracting when looking at point sources e.g. stars or distant lights. Field curvature/Petzval curvature- The image plane is not flat; it is instead a section of a sphere. The center of the image is in focus while periphery is out of focus, or vice-versa. "Plan" lenses are corrected for field curvature over 95% of the image.Astigmatism- this aberration, like coma, breaks the rotational symmetry of the optical system. The two orthogonal directions are called 'tangential' and 'sagittal' and rays in these planes focus to two different image planes. The effect is that defocus blur will be preferentially oriented, becoming rotationally symmetric at an in intermediate plane of focus (the 'medial' plane). 'Anastigmatic' lenses are corrected for astigmatism.Spherical aberration has become more familiar due to the quality of 'bokeh' (defined below). Spherical aberration is defined as the variation of focus with aperture: rays that cross the aperture stop at different heights are focused at different planes. Spherical aberration is always present in lenses made of spherical surfaces. 'Aplanatic' lenses are corrected for spherical aberration and include an aspherical element. Use of aspherical surfaces to fully correct spherical aberration is becoming more available as manufacturing technology improves.Chromatic aberrations: these are not related to the aberrations above, but refer instead to the dispersion of the lens. The two primary forms are lateral and axial chromatic aberration. Lateral chromatic aberration results in in-focus elements appearing as rainbows, while axial chromatic results in points appearing as colored bursts (and is associated with spherochromatism, below). This effect is more pronounced in out-of-focus components of an image. Use of different types of glass (e.g., the crown-flint achromatic doublet) reduces chromatic aberrations. Achromatic means 2 colors focus to the same plane; apochromatic means 3 colors focus to the same plane; superachromats are corrected for four colors. Achromats will be corrected for a blue and a red color (generally the 486.13 nm Hydrogen F-line and 656.28 nm Hydrogen C-line), apochromats will also be corrected for an intermediate wavelength (generally the 587.56 nm Helium d-line). The variation of spherical aberration with wavelength is called 'spherochromatism', and can this can be a dominant aberration in a well-corrected lens. Often the term 'purple fringing' is used to describe the effect, as objects will have dominant magenta or purple features.As the aperture increases, aberrations grow in magnitude and additionally, higher order aberrations become non-negligible (5th order is sin(q)^5/5!, 7th order, etc. Some high-end lenses are corrected all the way out to 9th order.Falloff– images will be brighter in the center than in the periphery. The edges of the image correspond to large incident angles of illumination, and so the geometric obliquity factor cos^4 becomes important. Because the projected areas of both the object and sensor with respect to the optical axis become smaller by factors of cos(q), the intensity varies for each as a factor of cos^2, thus leading to a total variation as cos^4. Especially noticeable using wide angle lenses, imaging at low f-numbers results in the edges of the image being noticeably darker than the center. This can be used to your advantage, by naturally drawing your attention to the center of the image. Digital cameras may incorporate Ôflat field correctionÕ to compensate for this.Flare– nonimaging light that does not pass normally through the lens, but instead enters the lens at an extreme angle and reflects off an interior surface before reaching the sensor. The usual effect in the image is a row of small bright images of the aperture (aperture ghosting). Typically associated with sunlight, lens flare can be controlled by a variety of methods including use of a lens hood, coating the interior structure with diffusing black paint, and adding internal baffles. Glare can also occur from reflections between a filter and the front element, or between the first few front elements in the lens itself. Often the result is desaturation of color.Bokeh is a Japanese term, added to the photographic vocabulary fairly recently. It refers to how out-of-focus objects are imaged to form a compositional element of the overall image. Ideal bokeh in background objects is produced by undercorrected spherical aberration, with the result that out-of-focus bright objects gently blur into the background. Overcorrected spherical aberration produces bokeh that is characterized by a bright halo around background object, and is considered unattractive.Image stabilization: lens/camera/tripod, mirror lockup: there are situations where camera motion becomes problematic: long shutter times (producing motion blur) and long telephoto lenses (high magnifications). Also, these cameras and lenses are often *heavy*. The image can be stabilized using a variety of technologies: the most basic is a tripod/monopod. With the advent of electronic sensors, manufacturers have been introducing motion-compensating mechanisms either within the camera body, and/or within the lens itself. Different manufacturers use different motion compensation technologies, and there are debates regarding the advantages of either. Regardless, image stabilization allows you to take sharp images several f-stops higher (or the equivalent change in exposure time) than without. 'Mirror lockup' is a technique that was developed to allow mechanical vibrations from the moving mirror to damp out prior to exposing the film- pressing the shutter once raises the mirror, and pressing it again will expose the sensor. Lastly, use of a shutter release cable (or remote electronic triggering) is used to prevent camera motion during the press of the shutter release.Filters: In addition to the use of color filters (either electronically or with a gel), other filters can be attached to the lens, usually via a screw thread at the front surface. A basic filter is a 'UV blocker', which reflects ultraviolet radiation and also places a protective glass surface in front of the lens. Some people attach a UV filter on their lenses rather than carry lens covers. There are also gradient filters, which present a gradient (either neutral density or colored) across the front element- this can be used to even out the illumination in a scene containing a very bright region (sun, bright sky, etc) and a dark region (shadows, etc.). These filters can be rotated to obtain the optional orientation. Polarizing filters come in two varieties, linear and circular, and are used to control sunlight that has reflected off of a flat surface: water, cars, etc. Using a polarizer when photographing a clear sky will emphasize the natural polarization of the sky. Due to the properties of autofocus sensors, a circular polarizer is generally preferred to a linearly polarizing filter- it is a linear polarizer in front and a quarter-wave retarder behind. Use of either a polarizer or gradient filter on a zoom lens should only be performed on lenses that do not rotate the front barrel during zoom; otherwise the filter will rotate with the lens, preventing control over the orientation of the filter.Rule of 16: The 'rule of 16' was developed during film, and it states: optimal exposure in bright sunlight is f/16, with the shutter speed set, in seconds, to 1/ISO. That is, slow film (ISO 100) uses a shutter speed of 1/100 seconds, while fast film (ISO 1600) would use a shutter speed of 1/1600 seconds. Since each f-number change halves the amount of light, the rule of 16 provides a starting point to estimate optimal aperture settings and shutter speeds.Hyperfocal distance: The hyperfocal distance is calculated by maximizing the depth of field: when a lens is focused at the hyperfocal distance, objects from infinity to half the hyperfocal distance are rendered in focus. The analytic result is: [tex] H = f( frac{f}{Fc}+1)[/tex],where H is the hyperfocal distance, f the focal length, F the f-number, and c the diameter of the circle of confusion. The hyperfocal distance also forms a series solution: focusing the lens at 1/2 the hyperfocal distance renders objects from the hyperfocal distance to 1/3 the hyperfocal distance in focus; focusing at 1/3 the hyperfocal distance covers objects from 1/2 to 1/4 the hyperfocal distance, etc. For example, the hyperfocal distance for a 28mm lens set to f/16 on a 35mm camera is about 1.6m. Everything from 0.8m to infinity will be sharp in a photograph taken with this lens focused at an object 1.6m away.Telephoto lenses are rarely used for hyperfocal distance focusing, as the hyperfocal distance is quite distant with these lenses. For example, the hyperfocal distance for a 200mm lens set to f/16 on a 35mm camera is about 86 meters. Everything from about 45 m to infinity will be sharp in a photograph taken with this lens focused at this hyperfocal distance. This lens isn't useful for taking a landscape photograph in which you want near objects to be sharp as well.Nodal, Pupil, and Focal planes– this section was added to clarify the large amount of confusing and conflicting information we encountered on many otherwise excellent websites while constructing this buyerÕs guide. All optical systems can be analyzed using six (cardinal) points: the front and rear focal point, the front and rear principal points, and the front and rear nodal points. In addition, the location of aperture stop (equivalently, the entrance and exit pupils) and field stop, if there is one, should be known. Although these concepts are used in geometrical optics, it can be helpful to describe the action in terms of physical optics.Focal points: Geometrically, rays initially parallel to the optical axis are brought to focus at the rear focal point. More generally, plane waves entering an optical system will focus to points (Airy disks) at the rear focal plane. When a lens is focused to infinity, the sensor plane lies at the rear focal plane.Nodal points: The front and rear nodal points are conjugate points with unit angular magnification. Rays passing through the front nodal point with a given angle exit the rear nodal point at the same angle. For lenses in air, the nodal points are located at the principal points.Principal points: The intersection of a principal plane and the optical axis is the principal point. Rays that intersect the front principal plane at some height, exit the rear principal plane at the same height: principal planes are conjugate planes that have unit transverse magnification. The distance between the front (rear) focal point to the front (rear) principal point is the front (rear) focal length.Entrance/Exit pupil: the aperture stop limits the cone of light from object points. The projection of the aperture stop into object space is the entrance pupil, the projection into image space is the exit pupil. When you look into a lens and see the aperture stop, you are actually seeing the entrance (or exit) pupil. All light that hits the sensor *must* pass through the entrance pupil, aperture stop, and exit pupil. Confusion arises when discussing panoramic imaging: rotating the camera to capture a large field of view. Rotating a lens about the rear nodal point does not produce motion of the image- swing lens panoramic cameras rotate the lens about the rear nodal point and have a curved image plane. More typical is 'stitched panoramic' images taken with a fixed lens and flat sensor. In this case, the lens should rotate about the entrance pupil to eliminate parallax error: near and far objects will maintain their relative positions when the lens is rotated about the entrance pupil.Miscellany: flash, lens adapters/converters: The flash that comes with your camera (if one does) may not meet your needs. Flash units can attach to your camera, or be designed to work remotely. Some cameras allow you to control an entire bank of flash units remotely. Lens converters: because different manufacturers use different lens mounts, there are adapters/converts than can allow you to use lenses made by one manufacturer on a camera made by another manufacturer. You may lose some functionality: for example, Nikon "series G" lenses do not have an aperture ring. New lens mount standards regularly appear (the latest is the four thirds mount). Generally, a camera with a lens mount that places the lens close to the sensor can be easily adapted to fit a lens using a lens mount that places the lens far from the sensor (the adapter is simply a spacer).I want to get the best digital camera there is and I don't care how much it costs.A: PF does not endorse any camera manufacturer or lens manufacturer. Our members are happy to answer any detailed questions, or discuss particular cameras and lenses with you.
I've never owned a camera, but I want to get a 'real' camera (that doesn't cost too much).I've owned an entry-level camera already and I want to take the next step. A: Usually called 'bridge cameras', 'prosumer cameras', or 'micro cameras', these cameras will allow you to have manual control over various parameters: the f-stop, shutter speed, ISO setting, etc. The lens is usually attached permanently. This type of camera can remain useful for about 3-5 years before technological improvements make it obsolete. This is where life gets interesting- there is a huge range of options, performance, and pricing. There is a bewildering array of options, and cameras can appear like a wallet, a beefed-up version of a point and shoot, or something that looks like a DSLR (digital single lens reflex). As a result, you should take some time to learn a few essential facts and concepts about optical imaging to determine what performance metrics are important to you. Furthermore, the amount of optional electronic processing available greatly increases- automatic face recognition, for example. Whether or not these 'features' enhance or inhibit your ability to take a quality image depends entirely on you; so make sure you can at least return all settings to factory default or turn them off. This section is longer than the other two, because it assumes you do not know any optics or imaging theory.Focal length – this is one of three key concepts in imaging. The focal length of a lens does not refer to the ability to focus. The focal length is one of the design parameters of a lens, and relates to the angular magnification. The angular magnification of a lens is equal to the ratio of back to front focal lengths. Thus, for example, a long focal length telephoto lens has a high angular magnification while a short focal length wide angle lens has a low angular magnification (sometimes less than 1). Angular magnification is not the same as the reproduction ratio: the magnification of the image with respect to the object. The reproduction ratio of most camera lenses is very small- the image of a person on the sensor is much smaller than the actual person, for example- even though the angular magnification may be very large (imaging someone who is far away). By convention, the designated focal length of a camera lens can also be stated as '35mm equivalent focal length'. This does not mean the actual focal length is useless information- it is needed to calculate the depth of focus and hyperfocal distance. If the actual focal length of the lens is specified and the sensor size is smaller than 35mm format, the field of view of the image will correspond to a 35mm image taken with a lens whose focal length is longer than the specified value. For example, a 35-150mm zoom lens on a four-thirds camera will produce images that have the same field of view as a 35mm camera using a 70-300mm zoom- this can be calculated knowing the 'crop factor' of the sensor (discussed below). Knowing the 35mm equivalent focal length is helpful when composing your image- human vision is very nearly equivalent to a 50mm lens (35mm format).One final note about focal length, regarding how your brain constructs depth information from a photo. The image is flat; your brain adds depth perspective to the image based on how your brain has learned to see with your eyes. Images taken with a 50mm lens on a 35mm format will appear very natural to your brain. Lenses with a shorter focal length will produce images that your brain will interpret as having exaggerated depth; conversely, telephoto lenses produce images that your brain will interpret as being compressed in depth. Part of this is related to the way angular magnification changes the relative sizes of near and far, but it also depends on how your brain extracts 3-D information from a 2-D image.f-stop/aperture setting: the second key concept. The f-stop (and related concepts like numerical aperture) is probably the most important concept in imaging theory. Camera lenses can be set to a series of discrete values of the f-stop (the f-number). The f-number sequence is logarithmic, and defined by first starting with '1' (f = D) and then using aperture diameters that successively halve the amount of light passing through the lens: the f-number sequence begins 1, 1.4, 2, 2.8, etc. Photographic lenses are specified in terms of their focal length and the minimum f-number available (largest aperture diameter): for example a 50mm f/1.4 lens, or a 70-200mm f/5.6 zoom lens. You don't need to memorize the sequence, but it can be useful to know what 'going up an f-stop' means. Some cameras allow for half-stop or third-stop increments, which is important for 'exposure bracketing' (see below). Just as the focal length has nothing to do with the focus distance, the aperture diameter is not the size of the front element. The aperture of a lens is a surface within the lens, and typically consists of an adjustable iris. A primary effect of varying the f-stop is to vary the depth of field. Two other important optical results are that both lens aberrations and optical resolution increase as the aperture increases. Most lenses on bridge cameras have moderately high f-numbers (say f/3.5 and up). This, in conjunction with the small sensor size, keeps levels of aberration down and the depth of field high. High f-numbers correspond to an accurate paraxial approximation (sin(q) = q) so the dominant aberrations are the 'primary' aberrations (discussed below). At high f-numbers, it is fairly easy to achieve excellent aberration correction, and images taken with these cameras will look good- uniform focus across the image, for example. Two important exceptions are distortion and chromatic aberration- those do not depend on the aperture, and thus may be the primary residual aberrations. Aberrations are discussed more fully below.A note regarding zoom lenses: zooms have become the dominant consumer lens, but are significantly more complex than fixed focal length ('prime') lenses and difficult to discuss in an introductory essay. The way elements within a lens move during focus is much different than how they move during a zoom. Zoom works by changing the magnification of a front group of elements, a rear group, or both. If zoom changes only a front group, the change in the focal length of the lens is exactly the same as the change in the diameter of the entrance pupil, so the f-number remains constant during zoom. If the magnification of the rear group changes, the f-number will change as the lens zooms. In practice, most lenses do the majority of their zooming with the front group, allowing the zoom to retain most or all of the maximum aperture setting. Again, the lens specification should indicate by how much (if at all) the maximum aperture changes during zoom. Exposure time– the third key concept. On one hand, setting the exposure is a trivial matter- long enough to get sufficient light onto the sensor. If you are imaging moving objects, it's a little more complicated- a long exposure will result in motion blur (which may or may not be desirable), so if you want to freeze the motion (short exposure), you have to use alternate methods- a flash, increase the aperture, or increase the ISO setting. The ISO setting is an adjustment to the electronic gain at the sensor- a higher ISO means more gain, which introduces more noise. Some cameras let you operate in 'aperture priority' or 'shutter priority', which means you actively control one (f-stop or shutter speed), and the camera optimizes the image by adjusting the other parameters automatically.Resolution: Now we come to a concept that is terribly misunderstood and often the subject of spurious claims. A detailed discussion about resolution is beyond the scope of this sticky, so for now we will simply distinguish between the maximum enlargement you can produce via a print and the ultimate resolution limit due to the lens itself. The print size is different from the display size: 72 dpi (dots per inch) looks great on your monitor, but terrible on a print. The professional standard for printing is 300 dpi. That may sound like a lot, but based on that specification, a 2 MP camera can produce a professional-quality 4 x 6 print. An 8 MP camera has sufficient pixel count to produce a professional-quality 8" x 10" print. Higher pixel-count (larger sized) sensors allow you to crop smaller regions (boring parts of the image) and still retain the ability to produce large professional-quality prints.The ultimate resolution a lens and sensor can deliver depends on the f-number, the degree of aberration correction, and the pixel size. For an aberration-free lens, points at the object are mapped to Airy disks at the image, the size of which are characterized by the distance from the central peak to the first minimum and is given by the Rayleigh criterion, which for visible light (0.5 micron wavelength) reduces to r = 0.6*(f-number) [in microns]. An f/4 lens produces an Airy disk radius of 2.4 microns, while stopping down to f/16 produces Airy disk radii of 9.6 microns. Pixel sizes should be not much larger than given by the Rayleigh criterion, or the sensor will limit the attainable resolution (Nyquist's sampling theorem). For this example, pixel sizes greater than about 3 microns on a side will result in sensor-limited resolution at f/4. A brief survey of pixel sizes currently in production indicate the typical camera has pixels 2-3 microns on a side, meaning the attainable resolution is more dependent on the lens than the sensor unless you are imaging with a fast (f/2.8 and below) lens.Enlarging an image past the performance limits of the lens (or digital enlargement beyond the capabilities of the sensor) results in 'empty magnification'; blur circles simply become larger blur circles. The rule of thumb is that empty magnification begins at 500/f-number. It is important to note that this rule of thumb is violated for camera sensors due to the Bayer filter and interpolation. Thus, using an f/4 lens on a 1/1.7" sensor limits the ultimate size of the image to less than 2m on the diagonal; recall at 300 dpi, the maximum professional-quality print size will be about 8' x 10'. To be sure, you could make a large poster out of the image, but it will only look professional from a distance. Crop Factor: The crop factor is the size of the sensor relative to the 35mm format. For example, a crop factor of 1.6x means the camera sensor diagonal length is 26.8 mm. All manufacturers use their own sensor format. Thus, it is helpful to refer to the crop factor' because the sensor is then expressed in terms of a standard- the 35mm standard. To calculate the focal length for your camera, given the 35mm equivalent focal length, simply multiply by the crop factor. Thus, a 200mm f/5.6 lens on a 1.6x sensor will actually appear as a 320mm f/5.6 lens mounted to a 35mm camera. Note, the f-number has not changed- the focal length and f-number of a lens is an intrinsic property of the lens. By changing the image size, different magnifications are needed to generate identical display sizes.Depth of field– a precise depth of field calculation is difficult to perform, since perfect focus exists only in a single plane. This subject is covered in detail in many other photography sites, so we will not repeat them here. A (relatively) simple formula can be written down using lens and camera parameters: the actual focal length f, the f-number F, the magnification m, (the ratio of object distance to image distance), and the diameter of the 'circle of confusion'. The circle of confusion is the size of the blur spot that your eye can barely resolve. Based on studies of visual acuity, c = 30 microns for 35mm format images. The formula is fairly straightforward: [tex] DOF = frac{2ffrac{m+1}{m}}{frac{fm}{Fc}-frac{Fc}{fm}}[/tex]where DOF is the distance range over which objects will appear in acceptable focus. For your camera, c = 30/(crop factor) microns. As specific examples, using the 35mm standard, a 50mm f/1.4 lens focused 10 m away has a depth of field of 3.5m, while the same lens stopped down to f/11 has an infinite depth of field (near focus = 4.3 m) (this is discussed below, under 'hyperfocal distance'). By contrast, a 200mm f/5.6 focused 100m away has a DOF = 102m. A 1/1.7" sensor using a 10mm f/5.6 lens will render all objects between 1.3m and infinity in focus. Small sensor digital cameras often do not have any out of focus components in an image. There are a multitude of free online DOF calculators available that have the relevant data for nearly all cameras on the market.ISO: ISO stands for the "International Standards Organization", and in imaging, refers to the sensitivity of film to light. The nomenclature carried over to digital imaging, and in this context refers to a level of gain (amplification) applied to the sensor output. In conjunction with exposure speed, the ISO setting will adjust your camera's light sensitivity. Doubling the ISO setting doubles the sensitivity. This can be used to retain a fast shutter speed to capture a moving target. Again, increasing the ISO setting increases the amount of noise present, and different manufacturers use their own idea of how to reduce the noise levels. It's not uncommon to find cameras with ISO settings up to 6400; ISO 102,400 is not unheard of. Because digital technology is so different than film, this standard has come under renewed scrutiny; however as a rule of thumb daylight imaging should be performed at ISO 100-200, indoor at ISO 400-800, and nighttime imaging at ISO 1600 and above.Exposure bracketing– getting a well-exposed image can be tricky, and there may not be a lot of time to adjust settings. Photographers learned a long time ago to perform 'exposure bracketing'. Instead of taking a single image, they would take a series of images through a f-stop interval, for example 3 1/2-stop increments through a full stop (- 1/2, 0, + 1/2). Digital cameras can achieve this by varying the f-number of the lens (shutter priority mode), the exposure time (aperture priority mode), or both. Some cameras allow for continuous shooting of an exposure bracket by simply repeated pressing of the shutter release. Frame rate– if you are interested in photographing moving objects, you may be interested in how fast a camera can take continuous images. The rates can vary, and some very clever autofocus routines have been devised to allow continuous autofocus while imaging a moving target.Image Histogram– Now that you are becoming familiar with the parts of a camera and how to control the amount of light incident on the sensor, you should understand a basic 'quality metric' of the image- the histogram. A histogram is nothing more than a graphical representation of the intensity levels in your image (a graphical representation of the dynamic range). There may be individual histograms for each (r,g,b) color, or one overall histogram. Either way, using the histogram will help ensure that your image is not underexposed (lots of black) or overexposed (lots of white). Three ways to control the brightness of the image have been discussed- adjust the aperture, adjust the exposure time, and adjust electronic gain. But, there are consequences to making adjustments to any of them- opening the aperture decreases the depth of field and increases the aberrations (discussed below), increasing the exposure time can lead to motion blur, and increasing the gain increases the amount of noise. Learning how to control these elements in your image will enable you to take better photographs (if that's a goal).Post-processing– Often, these cameras will have a multitude of 'on-chip' image processing options available: you can adjust the contrast, sharpness, saturation, etc. Whether or not you use these is up to you. Many manufacturers will include a basic image processing program bundled with the camera hardware. In addition to commercial programs, a free open-source image processing program (ImageJ) is available that you can download and use to manipulate your images- correcting the brightness and contrast, or color balance, cropping, etc.Pixel size vs signal to noise: here is another trade-off. Smaller pixel sizes can increase the ultimate resolution and maximize the final print size, but smaller pixels also have smaller light-sensitive areas and thus the sensor needs more light to generate a good signal-to-noise ratio. As we saw above, pixel sizes smaller than 2 microns on a side will not generally increase the attainable resolution in digital cameras. Micro cameras found in cell phones have pixel sizes approaching 1 micron on a side, and intensified cameras used in low-light applications often have pixel sizes around 15 microns on a side.Macro imaging: Macro imaging occupies the space between photography and microscopy. Objects are small (but not too small), and like microscopy, images are usually described in terms of the reproduction ratio. Macro lenses are designed to work close-focus and come in a variety of focal lengths. Longer-length macro lenses allow macro imaging of objects that are farther away: photographing insects at a distance, for example. Because the lens operates at close focus, control of the depth-of-field is critical; often the aperture is set very small and a flash (or several flashes) are used to allow a reasonably fast shutter speed.Autofocus: Autofocus is a complex multicomponent closed-loop control system consisting of a sensor (different than the image sensor), a control circuit, and a motor-driven lens. The time needed to find best focus will vary with aperture setting. Often, the manufacturer will have several autofocus modes: focus on the center of the image, find best focus over the entire image, or some other focusing algorithm. While some autofocus systems may be active (they emit IR light or ultrasound), most digital cameras use passive autofocus systems- either contrast measurement or phase detection. In general, phase detection is faster and more accurate, but both methods are constantly being improved. "Trap focus", or "catch in focus" are mechanisms that allow the camera to use autofocus as a detector, acquiring an image when an object passes into the focal plane- this is very useful for photographing fast-moving objects.Sharpness: another misused concept. At a minimum, "sharpness" implies a well-focused image using a well-corrected lens (aberrations are discussed below) with no motion blur. A related term is 'acutance', which describes the edge transitions between light and dark: a high acutance image can support very well-defined and rapid variations between bright and dark (high-contrast images). Due to image processing in human vision, a high contrast slightly blurred image will be perceived as being sharper than a better focused, lower contrast image.Memory cards: Most cameras require a memory card in order to store images. In addition to direct transfer of images from the camera to your computer, the camera will usually record the image onto a removable memory card that can permit much faster data transfer rates. Typical standard formats as Secure Digital (SD) and Compact Flash (CF). The camera may come with a card, or it may not- in any case, it's worth getting one with as much memory as you can afford. In order to use the memory card with your computer, you will most likely need a 'card reader' that essentially converts your memory card into a USB memory stick.
I've never owned a camera (besides what is in my cell phone and laptop). I want to take pictures at parties and post them online or email them to my friends.A: a compact point and shoot camera is likely the best option- everything is automatic, all you need to do is point the camera where you want and press the button. Because this camera does everything for you, you give up having control over most or all of the parameters discussed below. Most likely, you will either outgrow this camera or need to replace it in about 1 or 2 years.One important thing to look for in an entry-level camera is 'ease of use'. Chances are, you would rather take images rather than fiddle with camera settings. For example, are the buttons and dials easy to find and set? Is the LCD display sharp and bright enough to see in sunlight? Other priorities may include the ability to take a picture quickly (to catch moving objects like animals and small children), fast startup or turn-on times, portability, etc. These cameras produce very acceptable images that can achieve a professional-quality 4" x 6" print. We will have a lot more to say about resolution and print size later. At this level of performance, the sensor and the lens do not limit the image resolution- usually the automatic gain control and noise reduction do.At this level, you don't need to know any detailed imaging theory. However, we present some basic definitions needed to interpret the specifications on a camera and lens- these concepts will be refined in later sections. Then, we discuss what is inside the camera. Basic definitions: A camera lens will have some numerical specification, for example '18-200mm f/3.5-5.6', and the sensor will have some size specification, either a number of pixels (8 MP) or the diagonal dimension of the sensor (e.g. 1/1.7"). For the lens, the numbers '18-200mm' specify the rear focal length of the lens (in this case, a zoom lens with varying focal length between 18 and 200 millimeters). The rear focal length of a lens is not the distance between the lens and the sensor. There may be two sets of focal lengths- the actual and '35mm equivalent', and this is discussed more fully below. The term 'f/3.5-5.6' is the maximum f-number available for the lens (in this case, the maximum f-number varies with focal length). The f-number is defined as f/D, where f is the rear focal length and D the diameter of the entrance pupil (defined below). As you will see, the focal length and f-number are essential quantities to understand. For now it's sufficient to know that the focal length is a measure of the angular magnification of the image and with the f-number, is used to calculate the depth of field (DOF- the distance over which near and far objects are in focus). The f-number relates to a number of image metrics besides DOF, including the optical resolution and the amount of light passing through the lens. The f-number is usually controlled by varying the size of an aperture within the lens body. However, the size of that aperture is not 'D', above- D is the diameter of the entrance pupil. The entrance pupil is the projection of the aperture into object space. Put another way, when you look into a lens and see the aperture, what you really see is the aperture projected through the lens; since you are looking into the front of the lens, what you see is really the entrance pupil. The distinction may not appear significant, but in some cases (zoom and fisheye/ultrawide lenses and panoramic photography) it is.Digital camera sensors are often specified in terms of the diagonal length (like televisions), and just like televisions, the aspect ratio of the sensor may be 4:3, 3:2, or 16:9. The size of the sensor controls the field of view and also limits the maximum useful size an image can be enlarged. Because the image size is fixed, many imaging properties of lenses are interrelated: field of view and focal length, for example. Because there are no standard specifications for digital sensors, the practice of quoting 35mm equivalent focal lengths is done to provide a rational means to compare different sized sensors.What makes a digital camera special? A digital camera differs from a film in only two significant respects. First, and most obvious, a chemical emulsion (film) has been replaced by an array of electronic light detectors (pixels)- the sensor. A second key difference is what happens when you press the button to take a picture. In manual cameras, not much happens- a mechanical shutter opens for a set amount of time, exposing the film, and then closes. Digital cameras do a lot of things when that button is depressed, including light metering and focusing, all of which take time- this is "shutter lag" and is why the camera doesn't take a picture immediately. This can be a hassle when trying to photograph moving objects as they may move out of the frame (or focus) before the image is acquired. The 'half-press' is a technique that becomes very useful with these cameras for a couple of reasons. First, it lets the camera get ready to take an image (light metering, autofocus, etc) while you compose the shot. Second, many cameras will allow you to 'hold' the setting, reposition the camera, and then take a shot without changing the setting. This can be useful if you want something off-center to be in focus, for example. Another example is dealing with scenes with large variations in brightness- bright skies and shadowed valleys. Mastering the 'half press' can also alleviate a lot of lag time problems.Bayer filter: the pixels only detect the total amount of light incident; they do not distinguish colors. In order to generate a color image, sensor companies coat the sensor with an array of color filters, and the particular pattern has been standardized to a 'Bayer filter': Every other pixel sees green, and the other pixels alternate between red and blue. One important result from this is that the final image (say a color Jpeg file) has been produced by interpolating between pixels in order to appear that each image pixel has full color information. RAW images consist of the actual individual pixels and are used in more advanced photography, because each pixel retains its original identity and the photographer/print shop has more control over the final color print. Flash: Usually, these cameras have an automatic flash, so make sure you know how to turn it off: flash photography is often forbidden in museums, churches, etc. One important property of the flash is that closer objects will appear brighter than more distant ones, from the inverse-square law. This can result in a close person appearing bleached white, while the wall behind them is black. Also, because the flash is (relatively) low power, there is a limited useful range- the flash may not be able to effectively illuminate people more than a dozen feet away. Another issue related to flash photography is the "red-eye effect": light enters the subject's eye, bounces off the fundus, and back out of the eye- the red color comes from the blood vessels in the choroid. Because the problem is so common and pervasive, some cameras have a 'red eye reduction' mechanism which often consists of a series of bright flashes designed to contract the subject's pupil; make sure your subject doesn't think the picture was taken during those flashes and walk away.Gain: These cameras almost always have a high f-number lens. This provides a large depth of field (most of your objects will be in focus) and combined with the small sensor size, produce little aberration. If the aperture is fixed, the amount of light at the sensor is controlled by the shutter speed (or if there is no shutter, the integration time). Often there will be automatic gain correction (AGC) to control the sensor output levels to prevent bleaching (overexposure or white pixels) and underexposure- black pixels. AGC can introduce a lot of noise in your images- even indoor lighting, without a flash, can tax the gain level of your camera. Because of this, camera manufacturers add noise reduction schemes that result in a loss of fine detail. Dynamic Range: the dynamic range of an image, like any other signal, represents the amount of (intensity) variation that can be resolved. In a well-exposed image, there are not too many underexposed black pixels or overexposed white pixels. Visual studies have shown that human vision cannot distinguish more than 256 discrete grey levels: this is why computer displays are either 8-bit monochrome or 24-bit RGB color. Images with less than 8 bits (24 bit color) dynamic range appear 'posterized', while images with more than 8 (24) bits of dynamic range must be re-scaled prior to display. Sensors can have more then 8 bits of dynamic range- there are 16-bit sensors on the market- but increasing the number of bits does not automatically increase the maximum signal to noise ratio that can be supported. Images with more than 8 (24) bits allow more flexibility in post-processing to adjust brightness, contrast, and color balance (discussed below).Optical zoom vs digital zoom: Some of these camera lenses have zoom capability. Optical zoom means the lens has a variable focal length. Digital zoom is nothing more than digitally magnifying the original image- just like you can do on your computer. Digital zoom is rarely useful, and is usually combined with optical zoom to make the customer think the camera can do more than it really can. Optical zoom, by contrast, does represent a real increase in magnification and resolvable detail.White balance– the color of objects depends on the spectral distribution of illumination. For example, sunlit objects appear different if instead lit indoors under fluorescent lights. Film photographers used filters (gels) to compensate for or enhance this effect. Electronic cameras can do this without a filter by weighting the different colored pixels differently. Taking a picture of a white piece of paper using different white balance settings can be instructive. Often, indoor images have an orange cast to them: since fluorescent lights emphasize blue colors, the camera tries to compensate by boosting the orange tint.Live preview – this is simply using the LCD to display what the image would look like, in real time. Different effects can be previewed prior to imaging. Image stabilization – any relative motion between the sensor and subject while an image is acquired will result in Ômotion blurÕ. While this can be used to emphasize isolated elements of an image (moving wheels, for example), a uniformly blurred image is unappealing. There should be some image stabilization- at this level, manufacturers implement it electronically- but it will help your images appear 'sharp'.Shooting modes – Often, cameras will have a number of "modes": nighttime, landscape, people, cloudy weather, etc. These represent the manufacturer's opinion about the best fine-tunings for the camera parameters in particular lighting situations, and may or may not be useful to you. One popular mode is 'panoramic': multiple images are (later) combined to produce an image covering a field of view much larger than a single image. While there are some techniques to properly rotate the camera, the manufacturer's software is usually very forgiving of alignment errors- images will be stretched and distorted slightly to produce a seamless transition.Video is mentioned here only because some sort of video capability is becoming a standard feature. This sticky does not address issues specific to video other than general optical concepts that apply.
Looking forward to the rest of the series! One question though. With the meteoric rise in smartphone cameras, is the quick shot camera near death? I believe the only advantage at the moment is a bit of zoom?
I'm not interested with DSLR coz I find it complicated to use, lol. I have a Samsung Galaxy Camara. It works like a semi-smart phone too. The only difference is that you cannot make a call but you can send and receive sms. You can immediately post the photos to facebook and other social media channels. It is so easy to use.
[quote="Andre, post: 4085608"]Especially for Turbo, who once expressed the wish for an affordable full frame Canonhttp://www.dpreview.com/products/canon/slrs/canon_eos6d“Thanks, Pooh. I'd have to sell off some other gear in order to justify that camera, but it looks like a really nice package.
Especially for Turbo, who once expressed the wish for an affordable full frame Canonhttp://www.dpreview.com/products/canon/slrs/canon_eos6d
If you want to be able to compare lenses you should post uncropped 1:1 part of the image. At 640 pix even pictures taken with cheap, idiot cameras look perfect.And I think we should move the discussion to photography thread, or start lenses thread.
Well I got my new prime the other day and so far I really like it. Not only is the lens extremely well made but the IQ is incredible. I won't be able to put it through its paces until later this weekend but so far I'm very happy with it. I'm really tempted to get the DA* 55mm f1.4 but I guess I should pace myself and not blow my entire bank account on lenses.
Re: Zooms or Primes[quote="Topher925, post: 3589279"]What type of lenses do you experienced photographers prefer to shoot with most of the time. I currently only own two zoom lenses (one being the kit lens) and I'm thinking about either getting 1 or 2 primes or a nice large aperture zoom lens. I mostly care about image quality right now so I'm thinking about adding some primes to the collection but is there really that significant of a difference between a good zoom lens and a good prime? “Outdoors, I shoot a 15mm f/3.5(Nikon), 85 mm f/1.4 (Zeiss) and 400mm f/2.8 (Nikon). When I go wandering around, I'll take either the 15mm or 85mm (rarely both). I prefer primes for aesthetic reasons- it forces me to think more. For the macro/micro shots, I use more specialized equipment- I have a favorite lens just for reflected DIC imaging, a (different) favorite lens for transmitted DIC, another for phase contrast, another one or two for macro, others for darkfield, etc.There are good quality zoom lenses- some have a surprisingly large range of focal length. For me, I went to the extremes beyond zoom coverage- although there are 12-24mm zooms, they don't have an aperture ring and they have more distortion than the 15mm. I was considering the Voightlander 12mm, but I'd have trouble using that lens with my camera.It's important to realize that good lenses are designed to image a few things really well, so you should think about what you want to photograph- landscapes? wild animals? people? buildings? studio work? night/dim light? Each of those subjects has different requirements in terms of focal length and aperture. Again, there are some good zooms that can cover a large range of subjects.
Re: Zooms or PrimesI ended up purchasing a Pentax 40mm f/2.8 prime lens today. I figured I'd try it out and see how I liked it since prime lenses are suppose to be Pentax's specialty. [quote="Borek, post: 3589823"]How come you bought a Nikon and you shot with Pentax?”I ended up canceling/returning the order for the Nikon. After trying it out again at the store it felt too much like a soccer mom's camera. To add to that, nice glass from Nikon is very expensive. Sure, the lens selection for Nikon is much greater but it seemed that I needed to spend nearly twice as much to get decent basic lenses.The K-5 is a VERY nice feeling camera. Compact, sturdy, great ergonomics, and the weather resistance is a big plus too. “But when you find yourself constantly changing primes, missing shots, whereas you could have solved the situation with a simple turn of the zoom ring, make sure you have some zooms as well.”Right now I have the kit 18-55mm and DA 55-300mm lenses so I've got just about all the focal lengths covered. The kit lens will get replaced eventually (performs great for such a cheap lens though) and I really like the 55-300mm. I'll probably get the Tamron 17-50mm f2.8 somewhere down the road to replace the kit lens. I'm still shooting a lot and not quite sure what focal lengths I want in a walk around lens.
Yes the Pentax K-5 is a great camera, best in class for high ISO noise. But if you insist on comparing with Canikon, the available glass for Pentax is not the best. It may be harder to find what you like.A comparison between zoom or primes is apples and oranges. Yes primes trend to be sharper because they can be simpler but there are many (expensive) zooms outperforming (cheaper) primes. But when you find yourself constantly changing primes, missing shots, whereas you could have solved the situation with a simple turn of the zoom ring, make sure you have some zooms as well.Quality is expensive and this looks like a good onehttp://www.slrgear.com/reviews/showproduct.php/product/1234/cat/46
Re: Zooms or Primes[quote="Topher925, post: 3589279"]is there really that significant of a difference between a good zoom lens and a good prime?”In my experience – yes, primes are better.How come you bought a Nikon and you shot with Pentax?
Zooms or PrimesWhat type of lenses do you experienced photographers prefer to shoot with most of the time. I currently only own two zoom lenses (one being the kit lens) and I'm thinking about either getting 1 or 2 primes or a nice large aperture zoom lens. I mostly care about image quality right now so I'm thinking about adding some primes to the collection but is there really that significant of a difference between a good zoom lens and a good prime? Pic taken earlier today with the Pentax 18-55mm WR kit lens:
Excellent- hope you are having fun!
I know most people here shoot Canikon, but I cant say enough about how much I love my new Pentax. I finally got some time this morning to really try it out and while I'm still learning, I think the results are fantastic. Can't wait to get some nice lenses for it.
[quote="turbo, post: 3533989"]Well, I guess a pack of cards isn't that much of an investment, so we could spend a few bucks to split a deck and send one or two cards to others who want to use those as test targets.I'll send you some money to buy a deck of cards and pay for postage if you want to supply targets to Andre, Borek, and others. I can't get out too much due to my sensitivity to fragrance chemicals, so if you can handle the logistics, I'll pay the cost. It might be better to use cards within a single pack, to keep printing-variables as even as possible.”I'm not sure I want to open "Andy Resnick's Playing Card Emporium" just yet :) Interested people can buy them directly online, anyways:http://www.playingcardsandmore.com/bicycleplayingcards.aspx?gclid=CISzw92Py6sCFcjc4AodPgS63wAs it happens, I'm teaching the Advanced Optics Lab class next semester, and I've been trying to come up with a few labs to replace the (ahem) useless ones. For example, I'm thinking about a lab that centers on this:http://www.skymall.com/shopping/detail.htm?pid=203769555&c=10323and a "imaging performance" lab could also be a nice addition. I've come up with a preliminary procedure that I can debut here and see if it's worthwhile to fully develop for the course.So, for anyone interested in quantitatively measuring the imaging properties of a lens, I'll work to get a rough draft started in a new thread. Details to follow, but all you need to start is a greyscale photo containing a light-to-dark transition.
[quote="Andy Resnick, post: 3533981"]I was thinking more and realized that there doesn't have to be fine detail, as long as the pattern edges are sharp- it's still possible to extract the modulation transfer function.Cards sound good to me- consider that a second. How about the overseas folks?”Well, I guess a pack of cards isn't that much of an investment, so we could spend a few bucks to split a deck and send one or two cards to others who want to use those as test targets.I'll send you some money to buy a deck of cards and pay for postage if you want to supply targets to Andre, Borek, and others. I can't get out too much due to my sensitivity to fragrance chemicals, so if you can handle the logistics, I'll pay the cost. It might be better to use cards within a single pack, to keep printing-variables as even as possible.
[quote="turbo, post: 3533458"]No, Andy, there is not a lot of really fine detail on the card backs, but they could make pretty decent long-distance targets. Just trying to think of something cheap and consistent. <snip>”I was thinking more and realized that there doesn't have to be fine detail, as long as the pattern edges are sharp- it's still possible to extract the modulation transfer function.Cards sound good to me- consider that a second. How about the overseas folks?
[quote="Topher925, post: 3533308"]I ended up pulling the trigger on a Nikon d5100 w/kit lens and 55-300 DX VR lens last night. Amazon was having a killer deal where I got the stuff above and a camera bag for a little over $900 shipped. While I was leaning more towards getting the K-5, it just seemed like too good of a deal to pass up.”Congrats. I hope you enjoy it. Actually a few years ago I had a similar experience, I was charmed by the multigadget Sony A350 and I had already ordered it (tentatively), I thought that the Canon 450D, the other one of the shortlist, was way too simple and a bit expensive in comparison, then I saw the test results and I never looked at the Sony again.But that was just a moment in time and Nikon really had no competative model at that time that made it to my shortlist.
No, Andy, there is not a lot of really fine detail on the card backs, but they could make pretty decent long-distance targets. Just trying to think of something cheap and consistent. I long ago abandoned my wall-sized resolution chart (Edmunds, I think). When I was considering buying a zoom lens for my Olympus kit, I borrowed several from friends, including one who owns a camera shop, and used that chart to put the lenses through their paces. I gave up on the zoom idea right after developing and printing that film. It was with a bit of trepidation that I jumped in with a Canon 30D and 100-400mm L, because of the expense, but I have a friend on another forum who shoots wildlife/birds from a blind with the 100-400, and the quality is scary-good. Zooms have come a LONG way in the last ~40 years.
[quote="Andre, post: 3533292"]Impressive Andy and yes, resolution is a function of lens resolution and sensor resolution. But maybe this should go in another thread?”Probably- I think some sort of "shoot out at the PF corral" thread makes sense for this.[quote="Borek, post: 3533388"]Can we find or prepare some kind of test that each one of us could print to take pictures of?”All we need is a 'standard object' (or a few objects of different sizes if we want to go beyond macro shooting)[quote="turbo, post: 3533398"]How available are bicycle-brand playing cards in Europe? When the cards are new, they are very flat, and the printing quality on the backs is generally excellent and consistent to foil cheats.”This is a good suggestion- there does not appear to be very much fine detail, but it's probably good enough. How about the hologram sticker on credit/debit cards? Just a suggestion for something commonly available….Edit: I think it's worth saying that this isn't a "mine's bigger than yours" competition. There's a lot of optics knowledge that goes into setting up and quantitatively evaluating images, and this should be treated as an educational resource.
[quote="Topher925, post: 3533308"]I ended up pulling the trigger on a Nikon d5100 w/kit lens and 55-300 DX VR lens last night. Amazon was having a killer deal where I got the stuff above and a camera bag for a little over $900 shipped. While I was leaning more towards getting the K-5, it just seemed like too good of a deal to pass up.”Excellent- I think you will be very happy with your decision!
How available are bicycle-brand playing cards in Europe? When the cards are new, they are very flat, and the printing quality on the backs is generally excellent and consistent to foil cheats.
Can we find or prepare some kind of test that each one of us could print to take pictures of?
I ended up pulling the trigger on a Nikon d5100 w/kit lens and 55-300 DX VR lens last night. Amazon was having a killer deal where I got the stuff above and a camera bag for a little over $900 shipped. While I was leaning more towards getting the K-5, it just seemed like too good of a deal to pass up.
Impressive Andy and yes, resolution is a function of lens resolution and sensor resolution. But maybe this should go in another thread?
Here's some preliminary results using two resolution targets. The first is from Edmund optics and is a chrome on glass variable bar target:
and the second for higher-magnifications is a Richardson Gen III test slide:
The images below are taken from that small region in the dead center.There's a few things to keep in mind- first, although the targets are specified in terms of a length (for example, 5 line pairs per mm), the proper way to compare lenses is by the angular resolution: line pairs per radian. I didn't measure the object distance so I can't convert the units properly.Second, the pixelated nature of the CCD results in imaging artifacts, especially aliasing:
In this case, it shows the effect of angular misalignment between the bars and the pixels. A related issue is the Bayer filter, but from the point spread images I took earlier, that issue may not be a significant one.Lastly, for whatever reason I set the camera to 6 MP instead of the full resolution. This is probably a fatal flaw. In any case… From top to bottom are images from the 100mm, 63mm, and 25mm at full aperture, at the two useful extremes of reproduction ratio. For the 100mm, this is 1x and 1.78x (45 lp/mm and 75 lp/mm), while the 63mm images are at 2.5x and 4.5x (105 lp/mm and 190 lp/mm) and the 25 mm is 10.5x and 28.5x- the largest bars are 2 microns wide (4 microns per light/dark pair):
What I should probably do is re-take these at full resolution…
yes here is mine :biggrin:
Anyway, I would also be interested to see results compared to the Canon MP-E 65mm
[quote="Borek, post: 3530086"]Andre and I can take a picture of Canon's lens cap :smile:”From the inside? Your 100mm macros should deliver equivalent quality, I would think.
Andre and I can take a picture of Canon's lens cap :smile:
Sure you can compare with what we can and I would love to see results of that lens but it's not a game/match. I know that my 7D/100mm macro is not the best in the world, Borek beats it already with the 100mm L-version, but with a 5D mk2 body, results would even be better which would be topped by the A900, since the resolution is a function of both lens resolution and sensor resolution.But we can compare pix maybe of a yardstick, or matches or playing cards, or a certain common brand of batteries.
[quote="Andre, post: 3529689"]That's quite a statement. Would that imply that 50 years of innovations like aspherical, low dispersion elements and diffractive optics not could prevent that lens making deteriorated?”I stand by it. For whatever reason, Zeiss stopped making those lenses in the 1970's- none of those technologies (except possibly aspherical surfaces) which I agree could improve the optical performance of those lenses were ever incorporated. The fact that each lens has only three elements makes the optical performance even more astounding.I'd be happy to put my claim to the test- all we need is a 'standard object' that we can all photograph using whatever tools we wish. My only constraint is that I need to work indoors. Normally I would suggest a coin or piece of newspaper, but given the international participation in this forum, it's not obvious what the best choice would be.
[quote="Andy Resnick, post: 3528646"]I For example, my luminar lenses are 50 years old and I'm willing to bet they will outperform any contemporary macro lens, period- not just the optical quality but also the fact that they can be used on a 4" x 5" view camera (and possibly an 8 x 10). “That's quite a statement. Would that imply that 50 years of innovations like aspherical, low dispersion elements and diffractive optics not could prevent that lens making deteriorated?
You may be right about some of that. Over the years, I have owned a stable of Bronica Zenzanon primes, and Olympus Zuicko primes. I shopped carefully, and ended up with some superior lenses. Now, I can stroll around with a couple of Canon 30Ds and a few zoom lenses, to cover ranges from 18mm to 400mm. That's a whole lot handier than packing around two Bronicas and 4 primes, or 4-5 Olympus bodies and a corresponding number of primes. Another little wrinkle is that when you head out with bodies loaded with color negative film, color transparency film, Tech-Pan, etc, you can always end up wishing you had loaded films with different capabilities, different speeds, grain-size, etc. I can get a lot of flexibility on the fly with the DSLRs, and post-processing. I don't long for the days of film.
I think this discussion is a little too simple-minded. For example, my luminar lenses are 50 years old and I'm willing to bet they will outperform any contemporary macro lens, period- not just the optical quality but also the fact that they can be used on a 4" x 5" view camera (and possibly an 8 x 10). In terms of high-ISO/low light imaging, I'll put my EMCCD camera up against any DSLR. And it's not true that you are locked into a particular manufacturer, either.From my perspective, I have never been disappointed when I get the best camera/lens that I can afford: not the most expensive, but the equipment that best meets my needs, regardless of who made it. Of course, getting high-end equipment also (initially) showcases my inability to take advantage of the full performance- all flaws are glaringly obvious.
so let's continue the test. this what you'd have, if you scroll roughly halfway you see that the 350D (8mp) with the 18-55 averages about 1850 lines per height.Now you buy the super 17-55 to get this. See that the center is clearly better getting to 2100 lines per height. But the average is not increasing very clearly.Now we know from DPreview that the image quality of the 600D with 18MP is practically identical to the 60D and 7D, since it's the same sensor. The 50D here is slightly inferior to that, so we know that the 600D is certainly not going to give worse results here. But as shown here, the cheapo 18-55mm on the 50D gets us average results around 2200 lines per height.Consequently better glass is not dogmatic better than a better body. On the contrary, if you start comparing all the other nice improvements between the 350D and the 600D.
The too-cheap-for words 18-55 (no IS) lens on my 30D is remarkably sharp. I was initially turned off by the light-weight plastic body, etc, in comparison to my old Olympus lenses (OM system), but I was quite pleasantly surprised by the performance of the actual glass.
[quote="khemist, post: 3528143"]To be honest, get nice glass over a nice body. A sharp lens can make an aging camera come back to life.”Why not put that to a test.Suppose you own a Canon 350D with the too-cheap-for-words standard 18-55mm IS lens and you have something a bit short of a grand to spend. What would give you a better resolution (sharper pictures)?Get the legendary super 17-55mm F2.8 lens for your 350D or get a new Canon 600D body (less expensive) with the same cheapo standard lens?You can find the answer here.
[quote="khemist, post: 3528143"]To be honest, get nice glass over a nice body. A sharp lens can make an aging camera come back to life.And in the end, whatever camera you buy will work. It will have the ability to take good pictures, but its really who is behind the camera that really matters.”All true, and as Andre said above, one should select a system, not just a camera. Once you start adding high-end lenses to your kit, and maybe another camera body, you'll have an "investment" that is hard to recoup if you decide to switch brands. I decided that I liked the Canon brand, and liked their line-up of lenses so I started out there. Now, I have two 30D bodies and a selection of lenses, including a 100-400 L. I have not felt a driving need (or even want) to upgrade. The quality of this equipment is incredible, and the biggest limitation in the system is the "nut behind the wheel" (myself). Yes, there are shutterbugs who will try to stay on the bleeding edge, but that is expensive, even if you stay within your brand and chase body upgrades so you can keep using that expensive glass. Andre's shots have tempted me to consider a 100mm macro, but I shoot macro so infrequently that I have resisted the urge to splurge.
[quote="khemist, post: 3528143"]Just another tip. The MP doesnt really matter. Any camera nowadays will be able to perform fine. Unless you blow up your photos to poster size, no one will be able to tell the difference. [/quote]The disadvantage of high MP is noise, but the advantage is that you can crop more, getting more effective focal lenght from your glass.[quote]To be honest, get nice glass over a nice body. A sharp lens can make an aging camera come back to life.[/quote]Nicer bodies will still make that picture, where others can't, especially in high dynamic situations, you'll soon learn the difference. Edit: Like these for instance. and this…
And better glass is not necesarily more expensive glass. Moreover, if you want from excellent glass to splendid glass, you pay a nice body more.[quote] but its really who is behind the camera that really matters.”Absolutely
Just another tip. The MP doesnt really matter. Any camera nowadays will be able to perform fine. Unless you blow up your photos to poster size, no one will be able to tell the difference. To be honest, get nice glass over a nice body. A sharp lens can make an aging camera come back to life.And in the end, whatever camera you buy will work. It will have the ability to take good pictures, but its really who is behind the camera that really matters.
Anyway, this is one of my favorite crops:
Notice that the K-5 is excellent for noise but moderate on resolution detail. Notice also that the Canon 600D (Rebel T3i), sharing the sensor with the 60D and 7D, is just outperforming the D5100 with half a notch on details, despite the slightly worse performance on noise.
As I said earlier, buying an SLR is like marrying to that particular brand. Sooner or later more lenses are added in the inventory and then it's getting real tough to switch brands. Therefore looking at possible future desired lenses could assist, taking decisions.
I spent at least a good hour the other day checking out the A77 photos on dpreview and comparing to other camera's I'm looking at. While the JPEGs are questionable, the RAW files definitely bring out the shortcomings of the Sony 24MP sensor. I think I can cross that one off the list given the type of photos I want to take. I've been looking closely at the d5100 for a long time now, it truly is a fantastic camera for money. The fit and finish could be a bit nicer but for the price its acceptable. If I end up not getting the k-5 I'll most likely pick up the d5100.
Yes the D700 is very good at high ISO and outperforms the 5D MKII on some other things as well, except image detail/resolution due to only 12.1 MP versus 21.1MP. If you reduce the image size to the same 12.1 MP, you also reduce noise, while maintaining detail. I also should add that Andy's Sony A900 has the best resolution/detail but cannot keep up at higher ISOTo Topher925, you can find unlimited discussions here about the Sony A65/77http://forums.dpreview.com/forums/forum.asp?forum=1037
[quote="Andre, post: 3523795"]yes you are right noise is an issue with the new Sony's. Obviously with a fixed translucent mirror you lose some light going to the main sensor. So it's plain physics that signal to noise ratio is worse. However the 25 mp of the A77 reduces that problem somewhat if you reduce the output to 16MP. Another issue would be hot pixels, that emerge at long shutter speeds and high ISO, same problem there.The best signal to noise ration in relation to its price in DSLR's comes from the Canon 5D mkII (21 mp) especially at high ISO. The best absolute high ISO S/N ratio comes form the Nikon D3S (12mp) but at about double the price.”The Nikon D700 has much better noise reduction for the same price point as a mark 2. However, they are both outstanding cameras.Interestingly enough, the higher MP the mark 2 has contributes to the increased noise. My friend will shoot at ISO 6000 with the mark 2 and still get relatively noise free shots, but in comparison tests I have seen the d700 has less noise at almost all ISO levels.
[quote="Topher925, post: 3522550"]What is everyone's opinion of the Sony SLT A65 & 77 being released next month? I'm in the market for a new camera and so far have been looking at the Pentax k-5 for its low light performance and star tracker GPS thing. But with the A65 having such impressive specs for such a low price I'm really considering it instead.My only concern is low light performance. Given that its an SLT with ~2/3 of the light actually hitting the sensor coupled with the sensor having a very small pixel pitch makes me think that low light performance/noise will be rather poor compared to the k-5. Sony also limits the ISO to 16000. Whichever camera I buy a lot of its time will be spent doing some lite astrophotography so high noise is a big concern.”yes you are right noise is an issue with the new Sony's. Obviously with a fixed translucent mirror you lose some light going to the main sensor. So it's plain physics that signal to noise ratio is worse. However the 25 mp of the A77 reduces that problem somewhat if you reduce the output to 16MP. Another issue would be hot pixels, that emerge at long shutter speeds and high ISO, same problem there.The best signal to noise ration in relation to its price in DSLR's comes from the Canon 5D mkII (21 mp) especially at high ISO. The best absolute high ISO S/N ratio comes form the Nikon D3S (12mp) but at about double the price.
I don't recommend specific products- nobody pays me or provides equipment to use- but if your highest priority is low-light-level imaging, then you are right to carefully examine that spec.
What is everyone's opinion of the Sony SLT A65 & 77 being released next month? I'm in the market for a new camera and so far have been looking at the Pentax k-5 for its low light performance and star tracker GPS thing. But with the A65 having such impressive specs for such a low price I'm really considering it instead.My only concern is low light performance. Given that its an SLT with ~2/3 of the light actually hitting the sensor coupled with the sensor having a very small pixel pitch makes me think that low light performance/noise will be rather poor compared to the k-5. Sony also limits the ISO to 16000. Whichever camera I buy a lot of its time will be spent doing some lite astrophotography so high noise is a big concern.
[quote="Borek, post: 3257580"]I understand value of 1.6m for 28/8 can be calculated assuming circle of confusion of 0.03 mm and the 'real' focal length. Thats for a full frame camera. What values would be reasonable for APS-C?”Sorry- I didn't see this when you posted it. Varying the image size means the circle of confusion must be scaled (just as the focal length must be scaled). If the APS-C has a crop factor of say, 1.5x, the CoC is also divided by 1.5x so it would be 0.02 mm.The CoC specification was originally determined by using a standard enlargement of 8x viewed at 25cm; the reality is that viewing conditions and acuity affect the result.One counter-intuitive result (for me, anyways) is that larger format images (4" x 5" or even 8" x 10") appear sharper and have a more narrow depth of field than 35mm images.
I think that is worth some empirical trial and error [strike]work[/strike] fun.
[quote="Andre, post: 3257622"]So it seems that you get the oxymoron that the better the camera resolution, the less the depth of field and the farther away the hyperfocal distance.”That's why I asked for "reasonable"…
[quote="Borek, post: 3257580"]I understand value of 1.6m for 28/8 can be calculated assuming circle of confusion of 0.03 mm and the 'real' focal length. Thats for a full frame camera. What values would be reasonable for APS-C?”I guess if you don't change other facters that the crop factor 1.6 for Canon applies, hence 0.02 (0.01875).Mind that a CoC of 0.03 mm on a 24mm height compares to a resolution of 800 LPH (lines per height). However modern full frames easily get to 2500 LPH. So it seems that you get the oxymoron that the better the camera resolution, the less the depth of field and the farther away the hyperfocal distance.
[quote="Andy Resnick, post: 3091602"]Hyperfocal distance: The hyperfocal distance is calculated by maximizing the depth of field: when a lens is focused at the hyperfocal distance, objects from infinity to half the hyperfocal distance are rendered in focus. The analytic result is: [tex] H = f( frac{f}{Fc}+1)[/tex],where H is the hyperfocal distance, f the focal length, F the f-number, and c the diameter of the circle of confusion. The hyperfocal distance also forms a series solution: focusing the lens at 1/2 the hyperfocal distance renders objects from the hyperfocal distance to 1/3 the hyperfocal distance in focus; focusing at 1/3 the hyperfocal distance covers objects from 1/2 to 1/4 the hyperfocal distance, etc. For example, the hyperfocal distance for a 28mm lens set to f/16 on a 35mm camera is about 1.6m. Everything from 0.8m to infinity will be sharp in a photograph taken with this lens focused at an object 1.6m away.”I understand value of 1.6m for 28/8 can be calculated assuming circle of confusion of 0.03 mm and the 'real' focal length. Thats for a full frame camera. What values would be reasonable for APS-C?
Just wanted to tell that the new micro four thirds system (cropfactor 2) is maturing. A big leap ahead is made with the Panasonic GH2, from preliminary results I see that the image quality is excellent, on par or better than most of the APC-C format cameras (crop factor 1.5 / 1.6) like the CANON EOS7D or the Nikon D7000, that is on low ISO's. On higher ISO's -as expected- the image noise is clearly worse albeit that the image remains tack sharp.Micro four third cameras are hybrids half way between upper end point and shoot cameras and DSLR. The lens is exchangable but there is no mirror.It's not cheap though.
[quote="jtbell, post: 3091637"]Prior to the digital era, most film SLRs had automatic light-metering and many had autofocusing. When I bought a Pentax K1000 around 1990, it was one of only a few completely-manual SLRs still available, if I remember correctly.”I had a large stable of Olympus OM-1s and a single OM-4 with Zuicko prime lenses. I had two OM-1s that were dedicated to astrophotography. They were both dirt cheap at pawn shops because the meters didn't work. I think I paid $20 each for them. Still, they had manual shutters, mirror lock-up, interchangeable focus screens, and other features that made them perfect for astro-imaging. Plus, the OM series was smaller and lighter than about any other pro-grade SLR.
[quote="Greg Bernhardt, post: 3143917"]Just saw this now. Great work Andy!”Thanks, but I can't take all the credit- call me the 'lead author'. It was a collaborative effort from 3 or 4 of us (who can choose to identify themselves if they wish).
Just saw this now. Great work Andy!
I still have my Minolta XD7 and some lenses. So when I decided to go serious on photography again, selecting a DSLR, I first considered Sony/Minolta because my lenses may still be useable.But nope. Also lenses seem to age. Nothing automatic in there. I finally went for the Canon EOS 450D back in April 2008 because of superior image quality at that time.
I had a Nikon FG; no autofocus, but it did have metering (no autoexposure- I had to set the shutter speed and/or aperture manually). In addition, it had a full manual mode- if the battery was dead, for example- that provided a fixed 1/90 s shutter speed.
[quote="Andy Resnick, post: 3091595"]What makes a digital camera special? […] A second key difference is what happens when you press the button to take a picture. In manual cameras, not much happens- a mechanical shutter opens for a set amount of time, exposing the film, and then closes. Digital cameras do a lot of things when that button is depressed, including light metering and focusing,”Prior to the digital era, most film SLRs had automatic light-metering and many had autofocusing. When I bought a Pentax K1000 around 1990, it was one of only a few completely-manual SLRs still available, if I remember correctly.
Looking forward to the rest of the series! One question though. With the meteoric rise in smartphone cameras, is the quick shot camera near death? I believe the only advantage at the moment is a bit of zoom?