What is Medium: Definition and 389 Discussions

Medium format has traditionally referred to a film format in still photography and the related cameras and equipment that use film. Nowadays, the term applies to film and digital cameras that record images on media larger than 24 mm × 36 mm (0.94 in × 1.42 in) (full-frame) (used in 35 mm (1.4 in) photography), (though not including 127 sizes), but smaller than 4 in × 5 in (100 mm × 130 mm) (which is considered to be large format photography). In digital photography, medium format refers either to cameras adapted from medium-format film photography uses or to cameras making use of sensors larger than that of a 35mm film frame. Often, medium-format film cameras can be retrofitted with digital camera backs, converting them to digital cameras, but some of these digital backs, especially early models, use sensors smaller than a 35mm film frame. In the film world, medium format has moved from being the most widely used film size (the 1900s through 1950s) to a niche used by professionals and some amateur enthusiasts, but one which is still substantially more popular than large format. While at one time a variety of medium-format film sizes were produced, today the vast majority of the medium-format film is produced in the 120/220 film sizes. Other sizes are mainly produced for use in antique cameras, and many people assume 120/220 film is being referred to when the term medium format is used. The general rule with consumer cameras—as opposed to specialized industrial, scientific, and military equipment—is the more cameras sold, the more sophisticated the automation features available. Medium-format cameras made since the 1950s are generally less automated than smaller cameras made at the same time, having high image quality as their primary advantage. For example, autofocus became available in consumer 35mm cameras in 1977, but did not reach medium format until the late 1990s, and has never been available in a consumer large format camera.

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  1. aditya ver.2.0

    Refraction of light in denser medium

    Why does light bend in a denser medium?
  2. P

    Can a photon have mass when travelling through a medium?

    I know that a photon has no mass when it is traveling at the speed of light, however my question is, can a photon have mass when traveling through a medium, i.e. when its speed is less than c? I have done some reading but cannot find an answer. From this reading I have got the following: We...
  3. D

    Coefficient of friction of medium carbon steel

    i've been searching for the friction coefficient between medium carbon steels but can't find it, and also i see everywhere the yield stress of materials but i can't find the compressive stress of materials
  4. J

    Effective refractive index when two transparent medium are joined in s

    Dear All, If two layers of thickness d1 and d2 stacked on each other and having their absolute refractive index n1 and n2 . Can we find effective refractive index of the combination with this data? Thanks in advance. Jayesh.
  5. I

    Changing medium - Standing Mechanical Waves

    I wanted to ask the following question: If we change the medium of the wave (lighter or heavier) , how it will affect the particles velocity of the standing mechanical wave ? In my exam , there was a function's graph of one of the particles (of the standing wave) described with the...
  6. M

    Standard Sci-Fi Battles Using Fluid as the Medium?

    Hello! I'm working on creating a sci-fi setting for a tactical space combat video game and short story series, and I had a few questions I couldn't find much info on after googling. I'll be playing a little bit loosely with the laws of physics for the sake of gameplay and storytelling, but I...
  7. PhysicoRaj

    Electrostatic force in a medium of non uniform permittivity

    Homework Statement Two point charges, +4 μC and -10 μC are placed 10 cm apart in air. A dielectric slab of large area and thickness 5 cm is placed between the charges. Find the force of attraction between the charges, if the dielectric has a dielectric constant of 9. Homework Equations...
  8. M

    Is the intersteller medium a charged gas or a plasma?

    Hello Physics Forums! I've been educating myself on electrostatics, electronics, and electromagnetics and I have come to the topic of plasmas. I understand that plasmas are essentially charged gases - but their behavior is so disparate from regular gases that they are classified as the fourth...
  9. S

    Pressure drop across a filter medium vs. time modelling

    Hello guys, I am a computer science PhD student. But my project somehow requires some knowledge about computational fluid dynamic modelling (both discrete and continuous). nowadays I am abit stucked in an issue. I want to model pressure drop across a filter medium dynamically. i assume i have...
  10. B

    Oxidation number in acidic medium

    Hi everyone, In my school I was given a problem. It's that Cr2O7-2 + H2S in a acidic medium. And my teacher told that Chromium becomes Cr+3 . I want to know is there such a way to calculate the oxidation number in acidic medium. Or is it required the experience?
  11. S

    Laser Gain Medium Interactions

    I have a diode laser that emits multi-mode light. Two frequencies of this light are selected in an external cavity and reflected back into the laser diode. The laser diode's gain medium then resonate at these two frequencies and emits dual mode light. The laser operates in the 1550nm region...
  12. A

    Exploring Total Internal Reflection: Why Does Light Path Through a 2nd Medium?

    Hi And Need Help The main Question is what happens to light and cause go into next medium as total internal reflection happens for incident angles higher than critical angle ? so the main question is why the light path throughout the second medium? We know when light travels from a medium...
  13. M

    Resistance in a Medium Between 2 Spheres

    Homework Statement Two small conducting spheres with radii a and b are imbedded in a medium of resistivity ρ and permittivity ε with their centers separated by a distance d >> a, b. What is the resistance R between them? Homework Equations R = V/I I = ∫JdS = (1/ρ)∫EdS The...
  14. GreenAce92

    Is it possible to use air as a medium to display images?

    Yes holographs but not really So... I guess what I'm trying to get around is energy levels I will admit that my understanding is vague I believe I understand that certain gases are easier to excite (to give off light when going back down) like xenon but what about the general...
  15. R

    Medium Voltage Motors Phase Rotation Test

    Is it possible to check the phase rotation sequence of a Medium Voltage Motor (Up to 6 kV) with one instrument? Does the shaft need to be moving while it is being tested? If instead of one, there are two motors electrically connected in parallel, with a common source feeder. will it be...
  16. D

    Is light matter, or just a concept of vibrations in a medium?

    I've heard light compared to vibrations under the earth. The "waves" between the tectonic plates are simply a 'state', or 'action', i.e, the action of millions of atoms "bumping" into each other with their opposite charges (all the valence electrons repel other electrons). From my...
  17. C

    589.3nm +/- 0.3nm Absorption Lasing Medium?

    Does anyone know of a lasing medium (perferably something that can be doped into an optical fiber, but a liquid or gas would work if not) that has a strong absorption at 589.0nm and 589.6nm? Rationale: I'm trying to build a relatively cheap high powered (~300W-400W CW) LASER for DMLS, but...
  18. W

    Two Transverse Sinusoidal waves combine in a medium

    Homework Statement Two Transverse Sinusoidal waves combine in a medium are described by the wave functions: y1 = 3sin∏(x + 0.600t) y2 = 3sin∏(x - 0.600t) what is y1 + y2? Homework Equations the hint is that I am supposed to use: sin(α + β) = sin(α)cos(β) + cos(α)sin(β) The Attempt at a...
  19. A

    Heat of a bic lighter? A medium to lower it's heat?

    1.I know this is a weird question, but does anyone know what the temperature of a bic lighter is after around 5 seconds? If left on for a minute? In my research I have come across so many different answers and was hoping to get a more concrete answer. Once I have the needed testing apparatus I...
  20. E

    How Does Light Slow Down in Different Media?

    At the microscale, an electromagnetic wave's phase speed is slowed in a material because the electric field creates a disturbance in the charges of each atom (primarily the electrons) proportional to the electric susceptibility of the medium. (Similarly, the magnetic field creates a disturbance...
  21. S

    Prove v = u(ktu^3 + 1)^1/3 & x = (1/2ku^2)((ktu^3 + 1)^2/3 - 1)

    Question: When an object travels through a certain resisting medium the deceleration is proportional to the 4th of the velocity. This, a = -kv^4. Prove v = u(ktu^3 + 1)^1/3 and subsequently x = (1/2ku^2)((ktu^3 + 1)^2/3 - 1). v at time 0 = u and x at time 0 = 0. Equations: Differentiation and...
  22. Saitama

    Force on Dielectric Medium in the Presence of Point Charges

    Homework Statement Two point charges of magnitude q and 3q are located at a distance of 'a' from each other within an infinite dielectric medium of dielectric constant k. The force by the larger charge 3q, on the dielectric equals A)zero B)##\frac{1}{4\pi \epsilon_o}...
  23. D

    Effect on electrostatic force due to dielectric medium.

    Hi! I have a high school physics question. I know the concept of induction, and I also know what happens when a dielectric slab is placed between 2 plates of a capacitor. 2 charged particles are kept at a distance r. The mutual force of attraction/repulsion is F. What happens to the force...
  24. S

    Why does light bend when passing from one medium to another

    I know that light bends when traveling from one optical medium to another. The "classic" answer to this question is of course because the average velocity of light changes in the process. I've also seen other ways to make it "intuitive" enough to take it as a hard fact, eg. thinking of light as...
  25. anorlunda

    Speed of light in a dark matter medium

    The speed of light in a vacuum is the universal constant c. The speed of light in a medium is something less than c; let's call it s. Has the positive difference (c-s) been observed as light travels through ordinary matter in space such as gaseous nebula or plasma nebula? If no, is it...
  26. M

    Light waves propagate with no medium

    I have come to accept that the luminiferous aether does not exist. When we say that the electromagnetic wave is an oscillation of the electromagnetic field, then is not the electromagnetic field itself a medium that permeates all space? This is probably a dumb question, but I am as dumb as...
  27. U

    What Are Waves in a Dispersive Medium?

    Homework Statement Homework Equations The Attempt at a Solution i have no clue about the second part..
  28. V

    Action in the continuum limit for an elastic medium.

    Homework Statement https://www.physicsforums.com/attachment.php?attachmentid=57592&stc=1&d=1365348538 I'm stuck at the second part, not really sure what to here to be honest. https://www.physicsforums.com/attachment.php?attachmentid=57590&stc=1&d=1365346819Homework Equations Usually the...
  29. P

    Find the dielectric constant of the medium?

    Homework Statement Two point charges a distance d apart in free space exert a force of 1.4∗10^−4 [N]. When the free space is replaced by a homogeneous dielectric medium, the force become .9∗10^−4 [N]. What is the dielectric constant ϵr of the medium? Homework Equations E=F/Q The...
  30. C

    OPTICS: How to solve a two lens system with the object in a medium?

    Hi All, I need help determining focal length value in a two lens system. In the set up, the light source (object) is within a tube, a medium surrounds it with refractive index n1=1.52. The end of the tube is met with a curved convergent surface, the center of which is 0.635 cm away and focal...
  31. Saitama

    Theory of relativity - proton entering a medium

    Homework Statement (see attachment) Given data: 1.The speed of light in empty space is ##3 \times 10^8 m/s##. 2.The mass of the proton is ##1.67 \times 10^{-27} kg## . 3.The speed of light in water is ##2.3 \times 10^8 m/s##. 4.When photon emission begins to occur the initial proton, the final...
  32. E

    What happens to emission spectra when photons pass through a medium?

    I understand that light travels at “c” through any medium, and that the apparent slowing results from the absorption and re-emission of the photons by atoms in the medium. If this is the case, why, for example, are astronomers able to see the emission/absorption spectra of distant stars...
  33. T

    Consequences to a medium after ionising radiation has passed through?

    So I fully understand how alpha and beta can ionise different media. I also get why they can penetrate different media, but, what are the consequences (changes), if at all, to the media if after "absorbtion" or "penetration" a) What happens to a medium after radiation has passed through it...
  34. A

    Foucault pendulum string medium

    This question is literally driving me crazy. How does the String or rope or whatever is used in a Foucault pendulum not twist with the rotation of the Earth (because the rope is attached to bases that are attached to the ground). Actually if the bases are attached to the ground, that should...
  35. A

    Spreading of a pulse as it propagates in a dispersive medium

    Hello everyone! I am sorry but i couldn't put this into the template. I am studying the spreading of a pulse as it propagates in a dispersive medium, from a well known book. My problem arise when i have to solve an expression. Firstly i begin considering that a 1-dim pulse can be written...
  36. A

    Spreading of a pulse as it propagates in a dispersive medium

    Hello everyone! I am studying the spreading of a pulse as it propagates in a dispersive medium, from a well known book. My problem arise when i have to solve an expression. Firstly i begin considering that a 1-dim pulse can be written as: u(x,t) = 1/2*1/√2∏* ∫A(k)*exp(ikx-iw(k)t) dk...
  37. S

    Why Is Medium Acceleration Calculated Using Change in Velocity Over Time?

    This I something I always wondered, but never could get my finger into: ##a_m = \frac{v_2-v_1}{t_2-t_1}## Alright, that's medium acceleration, but why isn't it: ##a_m = \frac{a_2-a_1}{t_2-t_1}## I mean, it does make perfect sense in my mind. Is it just because it was defined that way?
  38. W

    Speed of light in lossy dielectric medium

    It is usually written that the speed of light in a dielectric medium is ##v=\frac{c}{\sqrt{\epsilon_r}}##, where ##c## is the speed of light in vacuum and ##\epsilon_r## is the relative permittivity. But, how can it be calculated for lossy and not necessarily low-loss dielectrics, i.e. those...
  39. A

    Propagating a Gaussian-Profile EM Wave in a Medium

    Homework Statement Hi everyone, As part of my final year project I am modelling the propagation of an electromagnetic wave through a medium of refractive index, n. I begin at the boundary between vacuum and the medium, x = 0 and propagate forward to some distance x. I have initially...
  40. S

    Does dark matter act as a medium for sound to go through?

    The title basically says it all, I'm wondering whether dark matter will allow sound to pass through because if it does, that could lead to being a way how to detect dark matter.
  41. A

    How to find an electric potential in anisotropic, inhomogeneous medium

    Hello! (I am sorry for probable mistakes. English is not my native language. I have never written anything about mathematics and physics in English.) I have an electrostatic problem. I need to find an electric potential \psi (\vec{E}=-\nabla\psi) in anisotropic, inhomogeneous medium...
  42. H

    Are polaritons simply photons propagating in medium?

    In vacuum, the photon has a 4-momentum (E, p) with E^2 - p^2 = 0, i.e. it's massless. However, upon entering a medium of refractive index n, we expect that the photon retains its energy, while reducing its momentum by a factor n (due to increased wavelength). We then have for the 4-momentum of a...
  43. B

    Is Space Considered a Medium for Photons and Other Waves?

    Hello all . Can we consider space as a medium that photons and other waves travel on that ?
  44. S

    Nerves cultured in artifical medium

    can nerves not be cultured in artificial medium? why? do nervers undergo cell division?
  45. D

    Neutron flux in a finite medium

    Deaar all good morning I am very interested to the flux in a slab of extrapolated thickness a, containing distributed sources of neutron. A I have an example in which the source is given as s(x)=S(x+a/2) where S is a constant and x distance from the center of the slab. You mentioned in one...
  46. D

    Electric Field In Medium Clarification

    So I just wanted to clarify: Because D = ε0E + P P being zero in vacuum and ∇D is constant regardless of medium if D was originally in a vacuum, the corresponding E would be greater than if it were in an insulating medium. So, E in vacuum > E in medium
  47. C

    What if light passes from lighter to denser medium

    hello guys, i need your help to clear my concept on total internal reflection ...when incident ray angle is greater than the critical angle for light passing through denser to lighter medium the total internal reflection occurs...and i know about corresponding snell equation and its validity...
  48. L

    Is the speed of light constant in a medium?

    One of the main postulates of relativity is that the speed of light is always constant. However, light does not always travel at c, it only travels at that speed in a vacuum (supposedly). When it is in a medium such as water or air, it moves at a noticably slower rate, where even other objects...
  49. M

    Relationship between the phase and group velocity in a conducting medium

    Is the relation v_{\varphi }v_{g}=v^{2}=\frac{1}{\mu \varepsilon } always true in a plasma ? Where v_{\varphi }, v_{g} are respectively the phase and group velocity of the electromagnetic wave that is propagating in the plasma.
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