What can we learn about the Milky Way using an 85mm lens and static tripod?

[Andy Resnick]

Here's a few stacks of the milky way I took last week, using an 85mm lens and a static tripod- 3.2s exposures. Two from the region around Cygnus:

And a panorama closer to the horizon (12 stacks):

This is about 13k x 11k pixels. At 100% the nebulae are still clear:

Unfortunately, I have to wait until next year before I can fill in those gaps...

 

[Drakkith]

Wow, very nice!

 

[davenn]

sweet !, nice work, really like those first 3

 

[William White]

very nice photos, but the pedant in me says that a normal lens is not 85mm; unless you have a very exotic camera?

(a 6x6 medium format has a normal of 80mm)

 

[davenn]

but the pedant in me says that a normal lens is not 85mm; unless you have a very exotic camera?

a normal lens would usually refer to a prime lens ... ie, not a zoom telephoto

not sure if Andy's 85mm is a prime or not ?? hopefully he will answer
@Andy Resnick
Dave

 

[William White]

a normal lens would usually refer to a prime lens ... ie, not a zoom telephoto

that's what I said! (I never mentioned a zoom telephoto (or long focus) - did anybody?)
I just noticed that it was taken with a normal 85mm and thought that's an exotic camera, which interested me

85 mm lens is normal on medium format.

 

[davenn]

you never mentioned prime lens either, and that is the pertinent point the camera doesn't have to be exotic ... any dSLR will do

 

[William White]

it goes without saying that a 85 mm normal lens is a prime,

I'm not sure why you are confused about this?
shall I start again? The OP said the photo was taken by with an 85mm normal lens

That intrigued me. Either it was a mistake, or a medium format camera was used.

 

[William White]

the camera doesn't have to be exotic ... any dSLR will do

any dSLRs will NOT do

for an 85mm normal the format has to be 6x6this is getting weird

 

[davenn]

Im not confused ... you were the one making odd confused comments LOL

 

[William White]

Im not confused ... you were the one making odd confused comments LOL

okay - let me explainThe normal lens used is 85mm.

A) This is either a mistake (the lens is NOT normal or NOT 85mm)
OR it IS normal and IS 85mm then
B) An exotic camera (6x6) was used.

If B, I am intrigued

 

[Drakkith]

shall I start again? The OP said the photo was taken by with an 85mm normal lens

Where did Andy say that? From the original post:

Here's a few stacks of the milky way I took last week, using an 85mm lens and a static tripod- 3.2s exposures.

 

[William White]

Where did Andy say that?

in the title
You quote the post that gives the focal length of the lens - not the type of lens (which is said to be normal in the title)

 

[Andy Resnick]

very nice photos, but the pedant in me says that a normal lens is not 85mm; unless you have a very exotic camera?

(a 6x6 medium format has a normal of 80mm)

Fine... call it a short telephoto. Of my 3-lens 'wide-normal-tele' kit, the 85 is my normal.

 

[Andy Resnick]

a normal lens would usually refer to a prime lens ... ie, not a zoom telephoto

not sure if Andy's 85mm is a prime or not ?? hopefully he will answer
@Andy Resnick

Dave

Yes, it's a prime (fixed-focal length). 85/1.4.

 

[William White]

that's the reason I asked about the camera Andy...

"Milky Way with a normal lens" means something very specific.

Generally, a normal lens is the highest quality lens for that system: fast; highly corrected for chromatic abberations and geometric distortion; sharp across the frame; very high (usually highest of the range) resolution and high micro contrast.

So it sort of made sense to me that a normal lens would be used for work where those qualities would be most useful (technical work) like your photos and I was intrigued that it was 85mm; which is a normal for medium format cameras: I thought you were using some sort of exotic 6x6 sensor, which I have not come across.It think, on a techical forum such as this, its best to use technical phrases and words that have a defined meaning in the correct way. Normal, in regards to photographic lenses, does not mean commonly or most often used.

 

[Andy Resnick]

that's the reason I asked about the camera Andy...

"Milky Way with a normal lens" means something very specific.

Generally, a normal lens is the highest quality lens for that system: fast; highly corrected for chromatic abberations and geometric distortion; sharp across the frame; very high (usually highest of the range) resolution and high micro contrast.

So it sort of made sense to me that a normal lens would be used for work where those qualities would be most useful (technical work) like your photos and I was intrigued that it was 85mm; which is a normal for medium format cameras: I thought you were using some sort of exotic 6x6 sensor, which I have not come across.

It think, on a techical forum such as this, its best to use technical phrases and words that have a defined meaning in the correct way. Normal, in regards to photographic lenses, does not mean commonly or most often used.

If I may, I agree with you that this discussion is a bit pedantic. But, in the spirit of sharing, etc, here's where I am coming from (optical imaging, as opposed to photography):

First, my sensor is a full-frame 35mm format, single chip with a Bayer filter. (Sony a850)
Second- my lens kit. I have a 15/2.8, 85/1.4, and 400/2.8 with 2x converter. Following photography parlance as I understand it, these are my 'wide angle', 'normal angle' and 'telephoto' lenses. To be sure, a typical photographer would say my wide angle is actually an ultra-wide, and my normal is a short tele. Whatevs... I use the tools I like.

In terms of optical quality, all three suffer from undercorrected longitudinal chromatic aberration, coma, and spherical aberration when wide-open. Usually I crop the images before posting them here to minimize the appearance of those. All three have some residual distortion, around 1% or less, which isn't worth correcting image-to-image but can cause problems when stacking.

Vignetting is also a problem, as is depth of focus (not depth of field)- the 15mm is *very* unforgiving- I've had to tweak the lens mount and it's still not exact. Fully open, the 85mm depth of focus is small enough that the sensor jiggling that occurs during shutter actuation means I either have to re-focus after every frame (impossible) or stop it down to f/2. Of the three, only the 400mm let's me focus past infinity- useful for compensating for temperature drift.

I also use my sensor with microscopes, which is a whole 'nuther discussion.

 

[Drakkith]

in the title

So it does. Touche.

 

[Andy Resnick]

Just to be extra-pedantic, the optical design of my 85mm is a double gauss, and thus primarily related to other 'normal' focal lengths (that is, the focal length is about equal to the sensor diagonal), while the wide angle is a retrofocus design and the telephoto is... well, a telephoto design.

 

[Andy Resnick]

Slightly off topic, but here's an image in Cygnus, taken with my telephoto, just the central 25% of the image:

I like this region because of the dust cloud in the center, it's located near the center of the bright stars 60 Cyg, HD199198, and HD199478. It's extremely dense and has a sharp boundary. This is one of the better stacks I've done, it even looks good at 200%:

Deets: 400/2.8, 13s exposures, ISO 1600, total integration time = 1 hr.

 

[Drakkith]

Andy, you make me want to get a DSLR camera!

 

[davenn]

Andy, you make me want to get a DSLR camera!

you don't already have one ?
am surprised

You also realize making a statement like that leads down the road of lots of spending ... but lots of fun

if you are serious ...
a suggestion or 2

a Canon 6D -- 20 MP full frame camera, awesome value for money with really good high ISO performance in low light.

a wide angle zoom lens something in the 14 - 35mm
and if you think you mite get into some deep sky imaging, like Andy and I do, a zoom telephoto in the 70 - 200mm range ( with as low a aperture (f-ratio possible)
my 70 - 200m is top end, f2.8 across the range

Now the fun really starts because once you have that cam and 70 - 200mm, you will need a tracking platform, there's quite a range out there ... google iOptron, they are a popular camera tracking mount and reasonably priced

Not sure how much you have looked into camera, lenses and star trails ??
hopefully not telling you something you already know

as a general rule of thumb, exposure time BEFORE stars start trailing in the image for a fixed mount camera ... 500 / focal length of the lens eg

500 / 50mm lens = 10 sec
D

 

[Andy Resnick]

Andy, you make me want to get a DSLR camera!

Glad to be of service :)

<snip>
if you are serious ...
a suggestion or 2

a Canon 6D -- 20 MP full frame camera, awesome value for money with really good high ISO performance in low light.

a wide angle zoom lens something in the 14 - 35mm
and if you think you mite get into some deep sky imaging, like Andy and I do, a zoom telephoto in the 70 - 200mm range ( with as low a aperture (f-ratio possible)
my 70 - 200m is top end, f2.8 across the range

Now the fun really starts because once you have that cam and 70 - 200mm, you will need a tracking platform, there's quite a range out there ... google iOptron, they are a popular camera tracking mount and reasonably priced

Not sure how much you have looked into camera, lenses and star trails ??
hopefully not telling you something you already know

as a general rule of thumb, exposure time BEFORE stars start trailing in the image for a fixed mount camera ... 500 / focal length of the lens eg

500 / 50mm lens = 10 sec

I don't think a full-frame format is required, the main thing is to have interchangeable lenses. But I agree, once you decide to step up to an interchangable lens system, first think carefully about the future- you want to spend as much money as possible on the lens(es); any digital camera is going to be obsolete in a few years, but a good lens will last you forever so pay close attention to the lens mount. While I don't use zoom lenses, there are definitely times when I wish I had that flexibility.

As for the star trails 'rule of thumb', in my experience it overestimates the exposure time by at least a factor of 2- granted, it matters what declination you are viewing. The good news is that if you already have a tracking mount, it's fairly trivial to adapt it for a camera- several companies make adapter plates, etc.

 

[davenn]

I don't think a full-frame format is required,

no it's not required, but if you are going to use a wide angle lens for say, Milky Way shots, you get better field of view with a FF compared to a crop sensor
for example, the Canon crop sensors have a crop factor of x1.6 so your 14mm wide angle lens will on a crop sensor will be 22.4 mm

In general the FF sensors have a better dynamic range than the crop sensors tho that gap is now growing smaller with some of the new cameras
and more importantly a better high ISO performance ( again, not wildly different but in really low light situations like astrophotography it all counts

The progression goes 7D-5D2-7D2-1D4-5D3-6D-1DX with about a 2 to 2 1/3 stop expanse covering these bodies. The bodies in bold only have perhaps a 3/4 stop difference.

and here's the killer, I didn't recommend the camera I use ( the Canon 5D3 ( 5D Mk3)) instead I recommended the 6D.
1) its around $1000 cheaper than my 5D3
2) its lighter ... really important for hanging off a telescope or on a camera tracking mount
3) it has better noise control at high ISO than my much more expensive and heavier 5D3

The 6D will outperform any Nikon except for the expensive 36MP D810
My 5D3 has features and other performance that the 6D doesn't have and hence I was happy to spend the extra money
The only time I would usually recommend a crop sensor camera like the Canon 7D Mk2 is for some one doing wildlife shooting
then that x1.6 crop factor on telephoto lenses is an advantage and that would also apply to deep space objects EXCEPT that it isn't as good in the high ISO so hence my 6D FF recommendation

The other recommendation would be the Sony A7 r mk2 but again getting into a higher price bracket
Sony make an outstanding CMOS sensor chip, pretty much the best out there ... and Nikon have recognised that and use it in their D810 and a couple of other higher end models.
Canon just isn't up with that yet, rather they have put more emphasis on excellent glass ( lenses)Dave

 

[Chronos]

I am stuck on the view that Canon is the unchallenged leader in DSLR photography.

 

[davenn]

I am stuck on the view that Canon is the unchallenged leader in DSLR photography.

Unfortunately ... from a body point of view, and it's well recognised, they have slipped in recent years
as commented earlier, they have put lots more emphasis into top glass and their sensor technology have slipped a bit
There's nothing wrong with the body build of my 5D3, it is extremely sturdy ... its purely a sensor thing

Sony really are the leaders in sensor tech and Nikon have recognised that fact and make use of them

there's only 2 cameras ( other brands) that really outdo my Canon 5D3, 22MP, and both are much higher MP
the Nikon D810 -- 36MP and the Sony A7R mk2 -- 42MP -- both them have around 1 - 2 stops better dynamic range
And they both have the Sony CMOS sensor

Canon have recently released the 5Ds and 5Dsr @ 50MP but these in particular the 5Ds are really cameras for well lit studio situations
and my 5D3 or the 6D will easily outdo them in low light photography situations

Nikon have to be congratulated tho ( and I'm not a Nikon fan ) they came out with the D810a a D810 variation especially for astrophotography
with a filtering system in front of the sensor specially designed to enhance Ha transmission from nebulacheers
Dave

 

[Andy Resnick]

From my perspective, the choice of specific tool (sensor or lens) is less important the the time and effort the user spends learning how to best use the tool. Discussions over which tool is 'best' are generally useless.

Edit: I mean to say, the best camera is the one you enjoy using.

 

[davenn]

...Discussions over which tool is 'best' are generally useless.

would have to disagree with that, not really useless ... there are cameras and then there are CAMERAS !
and capabilities vary greatly between models as I started getting into in my previous 2 posts

It is important to get a camera that is suitable for your specific photographic needs

1) family and holiday snapshooter ... just about anything will do from your smartphone camera and upwards
2) serious amateur ... then start considering what types of photography ... wildlife, landscape, astro, portrait etc
3) semi-pro to pro ... again you need to consider your specialty area of work --- crop sensors are much better for wildlife than for wedding and portraiture where full frame is better suited

Edit: I mean to say, the best camera is the one you enjoy using.

a little truth in that ... the other old saying is " the best camera is the one you have with you" and that is even more important
I am NEVER without a camera in the car and often 2 or 3 ( including the smartphone one)

Now here's an example of importance of suitable camera ( rather than "the one your like to use")

That camera that's always in the car is an old Fuji S9500, a 2007 vintage and it can do my lightning video work that all the newer cameras fail at
including my 5D3. WHY ? ... because its an old CCD sensor with the global shutter. All the new CMOS sensor cameras have rolling shutters
and they totally screw up the lightning zap captures because they cause dark and light bands across the frame of the video ... it a flamin' nightmare

My 5D3 does awesome quality HD video, but it like the other rolling shutter cameras, is useless for lightning capture video
The old Fuji's video is pretty low quality in comparison and only 640 x 480 resolution but at least the lightning zaps look awesome

I want a camera with HQ video and a global shutter ! ... VERY specific cheers
Dave

 

[Andy Resnick]

Here's my more-or-less final panorama, after considerable use of NeatImage, Hugin/enblend/enfuse, and ImageJ/CLAHE:

Actual image size is 15k x 13k pixels, generated from 17 different image stacks, each image stack has about 2 minutes of total exposure time (about 40 images per stack).

 

[Drakkith]

Well, it looks good on my phone's little screen. I'll get back to you when I get home and can see it on my computer.