Film vs digital for long exposures

[Steven Ruttenberg]

I understand reciprocity rule so not my question. My question is this: When I use film, like asa 100 extar, provia, etc I am able to take very long expsoures, like 5-10 minutes or even longer and I do not notice any "noise" grain in the pictures making them unusable. When I shoot digital, I have to watch for temperature, length of expsosure, use noise reduction in pre and post. The hotter it is outside, the longer the exposure, the worse it is is. Especially when you have a firefly convention. It is a lot of work to take dark frames, bias frames, light frames stack them proprly, etc to get an image especially if your image is more than about 30 seconds in length, even at iso 100 (or the native iso for the camera) And when you are employing tilt/shift/rise/fall with the lens (I use Canon TS/E lens for digital stuff) your sensor just gets plain hot.

Anyway,
Am I correct in that I can take very long exposures with film and not have any similar problems to worry about. I have made some at 5-7 minutes in length, fairly warm out and did not see any degradation of the image. so is there a point in which film will not yield satisfactory results with the grain/noise becoming too much? Like I stated though, I have not seen it, yet, that is.

[Willie]

Have done exposures on both B&W and Chromes up to 20 minutes without any problems. Velvia at 20 minutes goes a bit magenta - but since it was western sky reflecting on water well after sunset the magenta helped.
My uncle has done 8 hour exposures in very dim buildings and the negatives look good and print well.

[Steven Ruttenberg]

Have done exposures on both B&W and Chromes up to 20 minutes without any problems. Velvia at 20 minutes goes a bit magenta - but since it was western sky reflecting on water well after sunset the magenta helped.
My uncle has done 8 hour exposures in very dim buildings and the negatives look good and print well.

Cool.

[Corran]

Film has reciprocity as you mention as well as color shift depending on the type of film. There is no change in grain - that is inherent to the film.

The issues with digital are sidestepped by using multiple exposures and blending, but the slight delay between exposures may be a problem in certain situations.

So there's different pluses and minuses and so you might choose one or the other depending on the photo. I have shot very very long exposures on film and digital - digital is much easier for startrails which I like to do. Slight delay is masked in the software I use and becomes irrelevant. I limit length to 30 seconds usually.

[Steven Ruttenberg]

If astrophotography then digital. If long exposures of city scapes etc especially at night then film for the most part.

[LabRat]

Despite reciprocity, speed, and contrast build-up, at least film does not build up other artifacts during exposure...

Steve K

[Steven Ruttenberg]

Despite reciprocity, speed, and contrast build-up, at least film does not build up other artifacts during exposure...

Steve K

True. Digital noise of all types is a pain to deal with.

[xkaes]

I've taken many 6-8 hour exposures on Agfacolor 100, 125, and 400 during the winter -- of the SW desert landscapes & skies. The only possible problem is color shift -- but that's hard to determine because it's so dark you really can't tell what color it's supposed to be! So when I see the results, I might like it -- and if I don't, I can change it.

The other issue is metering of the scene. You need a very sensitive meter, but you can't use the reading directly -- or you will end up with a very bring scene, not a dark, night-time scene.

Oh, the other problem I've had is remembering to bring an alarm clock to wake me up before sunrise! Dew is usually not an issue in the Desert SW.

[Steven Ruttenberg]

Marines cured me of getting up early, no problem!

[Jim Jones]

A lens hood fitted with a very low power heat source may prevent condensation from dew.
As for B&W, I've done star trails up to 12 hours on Tech Pan. Predicting the correct exposure may be the worst problem.

[Pere Casals]

Have done exposures on both B&W and Chromes up to 20 minutes without any problems. Velvia at 20 minutes goes a bit magenta - but since it was western sky reflecting on water well after sunset the magenta helped.
My uncle has done 8 hour exposures in very dim buildings and the negatives look good and print well.

It is the counter, long Velvia exposures get a green cast so a magenta filter is recommended for it, for 2 to 8min a 2.5M filter should be used , see here page 2, section 6 ; http://www.fujifilm.com/products/professional_films/pdf/velvia_100_datasheet.pdf

[BennehBoy]

I shot my first long night expsoure ever this summer. Shot on Kodak E64T in 8x10. It's still waiting to be souped, anyhow it was a 2 minute exposure which I believe is well within the norm for this film.

I scan everything anyway so if the colours are off I'll just adjust in PP.

[Willie]

It is the counter, long Velvia exposures get a green cast so a magenta filter is recommended for it, for 2 to 8min a 2.5M filter should be used , see here page 2, section 6 ; http://www.fujifilm.com/products/professional_films/pdf/velvia_100_datasheet.pdf

Must have been the sky color over the horizon influencing the color of reflections.
You are right. I was thinking of these images - not the normal forest floor shots where the green worked with the plants in deep shade.

[Pere Casals]

Must have been the sky color over the horizon influencing the color of reflections.
You are right. I was thinking of these images - not the normal forest floor shots where the green worked with the plants in deep shade.

For long exposure Velvia 50 requires stronger magenta filters than Velvia 100. This is 5M for 4min and 7.5M for 8min. This has great importance because base exposure for Velvia 50 is twice longer, so at the end for the same shot Velvia 100 needs a 2.5M correction it happens that Velvia 50 needs 7.5M correction. I prefer V50, but for long exposures V100 is way more convenient...

[Steven Ruttenberg]

I wonder if converting to bw after scanning would filters be needed prior. Of course get it right in camera is a must. I also wonder on bw film if filters would be needed after a certain length of exposure.

[Pere Casals]

I wonder if converting to bw after scanning would filters be needed prior. Of course get it right in camera is a must. I also wonder on bw film if filters would be needed after a certain length of exposure.

Hello Steven,

Using right filters at taking time can be very important, both with color and BW, and both for digital and film. And filters can be also very important for long or short exposures.

Think that at taking time you reduce spectral (rainbow wide) information for each scene point to a single gray level or 3 (RGB) color values. After shutter release you have lost spectral information in an irreversible way.

If you convert a Col image to WB you won't be able to recover the colors from the BW image, in the same way when you reduce the scene spectral brightness to RGB you cannot later restore the spectral field, so what you do at taking time can be critical.



Today there is a tendence to think that Photoshop does all, but this is wrong, what is true in that Photoshop modifies all.

A good way see the importance of that is understanding how Hollywood cinematographers work for $200M products, they have a legion of illumination technicians and an expert colorist team working for the image capture.

[barnacle]

...I do not notice any "noise" grain in the pictures making them unusable. When I shoot digital, I have to watch for temperature, length of expsosure, use noise reduction in pre and post. The hotter it is outside, the longer the exposure, the worse it is is.

It's a fundamental difference between the electronic sensor and film: in any electronic sensor you have unavoidable thermal noise which adds to the signal you're trying to catch. So you have a final image consisting of both photon-generated electrons and thermally generated electrons; if there isn't much light (and why else would you want a long exposure?) then there's a lot of time for the thermal noise to build up. With a photographic film, while you are still relying on light to kick electrons around in the emulsion prior to development, it's nowhere near as sensitive as the electronic system - and if the incoming photon has insufficient energy, it won't affect the image at all. While thermal noise is still generated in the film, the film is so insensitive to it that film will keep for years (though it does - slowly - fog from this effect over time).

Neil

[Steven Ruttenberg]

Hello Steven,

Using right filters at taking time can be very important, both with color and BW, and both for digital and film. And filters can be also very important for long or short exposures.

Think that at taking time you reduce spectral (rainbow wide) information for each scene point to a single gray level or 3 (RGB) color values. After shutter release you have lost spectral information in an irreversible way.

If you convert a Col image to WB you won't be able to recover the colors from the BW image, in the same way when you reduce the scene spectral brightness to RGB you cannot later restore the spectral field, so what you do at taking time can be critical.



Today there is a tendence to think that Photoshop does all, but this is wrong, what is true in that Photoshop modifies all.

A good way see the importance of that is understanding how Hollywood cinematographers work for $200M products, they have a legion of illumination technicians and an expert colorist team working for the image capture.

For my digital work, I always use a filter on most all landscape scenes. I mostly use Grad NDs and such. When I shot film in the past, I would use red, yellow, green filters for b/w. With digital, you can simulate that to a high degree, with certain processing techniques in PS. But alas, you are not recording the full amount of each color rbg with a digital sensor, but you are able to cook a new formula if the previous processing wasn't to your liking. With film as you say, in camera is best especially for b/w film as it is a one and one and after that, you can't retrieve the original scene information the way you can digitally. So, your choice of filter for the shot is really very important.

But part of what I am looking at is going back to old school. There are so many out there who rave on a b/w white made from a color digital file, when I look at them I don't really see the rage about them. An actual b/w piece of film has more in it than any digital has, also, if you are shooting color, then you still have much more info in the "color" channels than you will with digital, ever, unless they truly figure out how to do away with the bayer filter.

[Pere Casals]

For my digital work, I always use a filter on most all landscape scenes. I mostly use Grad NDs and such. When I shot film in the past, I would use red, yellow, green filters for b/w. With digital, you can simulate that to a high degree, with certain processing techniques in PS. But alas, you are not recording the full amount of each color rbg with a digital sensor, but you are able to cook a new formula if the previous processing wasn't to your liking. With film as you say, in camera is best especially for b/w film as it is a one and one and after that, you can't retrieve the original scene information the way you can digitally. So, your choice of filter for the shot is really very important.

But part of what I am looking at is going back to old school. There are so many out there who rave on a b/w white made from a color digital file, when I look at them I don't really see the rage about them. An actual b/w piece of film has more in it than any digital has, also, if you are shooting color, then you still have much more info in the "color" channels than you will with digital, ever, unless they truly figure out how to do away with the bayer filter.


Both with digital and film you can shot in color and later making the BW conversion. This always delivers a degree of flexibility, you can apply color filtering in the post process, so you have an extensive color filter bracketing from a single shot.

A BW artist can be very reluctant to use color film to later make a BW conversion, for well known reasons (Image Quality, cost, workload, +/-N ...). Anyway this is possible and some have used this way, making museum grade BW prints from LF Velvia shots.


For digital, there was the Leica M Monochrom with sensor with no bayer tiles, this is an exception. As common photography sensors usually have that bayer filter, I agree best option is to use the color raw file to make the conversion in the PC, rather to shot monochrome "in camera", as you have more flexibility in the post, as you said.

https://www.bhphotovideo.com/c/product/860536-REG/Leica_10760_M_Monochrom_Black_and.html

[Willie]

It's a fundamental difference between the electronic sensor and film: in any electronic sensor you have unavoidable thermal noise which adds to the signal you're trying to catch. So you have a final image consisting of both photon-generated electrons and thermally generated electrons; if there isn't much light (and why else would you want a long exposure?) then there's a lot of time for the thermal noise to build up. With a photographic film, while you are still relying on light to kick electrons around in the emulsion prior to development, it's nowhere near as sensitive as the electronic system - and if the incoming photon has insufficient energy, it won't affect the image at all. While thermal noise is still generated in the film, the film is so insensitive to it that film will keep for years (though it does - slowly - fog from this effect over time).

Neil

Might want a long exposure for effects on water, clouds, moving subjects? Or to have a scene where the people walking through don't show at all because they are not there long enough to register on film?

[barnacle]

I take your point about the various reasons for the long exposure, Willie, but in any case when a long exposure is used there is very little light arriving at the film or sensor. Either there isn't much light out there in the world - the night sky, the dark cathedral interior - or you have a very small aperture and/or ND filters in front of the lens to restrict the amount of light coming in.

Either way, there's not a lot of photons arriving at the film/sensor, and in the case of the sensor, the thermal noise is adding to the signal generated by the photons. With halide emulsions, this doesn't significantly happen; if enough electrons fail to arrive in a given time, the activated halide decays to its ground state - hence the toe of the response curve and the low-light reciprocity effect.

Neil

[AtlantaTerry]

Back in the '70s, I photographed an old vaudeville theatre that was being restored near Pittsburgh, Pennsylvania USA. After I lit it and then composed one particular view from the balcony using my 90mm f/5.6 Super Angulon on my Toyo monorail view camera, the exposure using 4x5" Kodak tungsten color sheet film calculated to be 30 minutes for one exposure, which is what I did. I seriously doubt if I could do the same thing with my current Nikon digital cameras.

One thing that I have learned is that tungsten film has fewer problems with long exposures. I believe some photographers use tungsten film in daylight (with color filters to adjust the white balance) when they know they are going to need a long exposure.

Every tool is different. We as photographers need to know what to use and when.

[Pere Casals]

Back in the '70s, I photographed an old vaudeville theatre that was being restored near Pittsburgh, Pennsylvania USA. After I lit it and then composed one particular view from the balcony using my 90mm f/5.6 Super Angulon on my Toyo monorail view camera, the exposure using 4x5" Kodak tungsten color sheet film calculated to be 30 minutes for one exposure, which is what I did. I seriously doubt if I could do the same thing with my current Nikon digital cameras.

One thing that I learned was that tungsten film has fewer problems with long exposures. I believe some photographers use tungsten film in daylight (with color filters to adjust the white balance) when they know they are going to need a long exposure.

Every tool is different. We as photographers need to know what to use and when.


This should have a technical reason.

My guess is that different color sensitive layers in the emulsion have different reciprocity failure behaviour that ends in a color shift, this can be solved at taking time by using the proper correction filter. By using Tungsten equilibrated film for daylight long exposures we just enhance sensitivity to blue light, solving a share of the problem.

Perhaps silver halide emulsion for different color layers have different speeds, for example to compensate for the practical optical density the image forming rays have to cross to reach a particular color layer. So if there are different kinds of emulsion this may result in different LIRF, so in color shifts for long exposure.

Just my guess

[Corran]

the exposure using 4x5" Kodak tungsten color sheet film calculated to be 30 minutes for one exposure, which is what I did. I seriously doubt if I could do the same thing with my current Nikon digital cameras.

I don't know what Nikon DSLR you have, but the exposure on digital using the base ISO at a reasonably equivalent aperture for depth of field and with no reciprocity issues of course would probably be much, much less time. Consider that the Milky Way can be reasonably captured with a 10-20 second exposure with a reasonably bright lens and ISO 400 or so on digital. I've shot in very dim abandoned places with my DSLR and not needed more than 30 seconds of exposure.

Your experience with long exposures and such on film may trump the ability to do the same on digital. More importantly in my view is that sometimes I want longer exposures on digital but need ND filters to achieve them due to the higher sensitivity and wider f/stops in general use before diffraction.

[Corran]

Steve asked though "I also wonder on bw film if filters would be needed after a certain length of exposure." The answer is no. As far as I understand, there is no change in spectral response of b&w materials with long exposure. Someone can correct me if I am wrong. I don't believe the question was posed in terms of color film vs. b&w film though. The suggestion to shoot color film and convert to b&w later as a method of "control" is only valid if one is not printing traditionally in the darkroom, unless the idea is to use color filtration and make an intermediate b&w negative via contact printing off the chrome, which seems to me to be a rather roundabout way of doing it. Or burning a new image via LVT.

[Pere Casals]

spectral response of b&w materials with long exposure.

Hello Bryan,

BW films have some changes in its spectral sensitivity depending on some factors. But IMHO this is not a concern because this a minor change compared with the strong filtering a photographer may use.

Kodak charts Density vs Spectral response:

170904

(This Kodak TMY graph has an error, 0.3D under top curve should read 3.0D)

As LIRF changes density balance it also has to change linear response for different colors, but IMHO nothing to worry about.

Modern films can have two layers of silver halide emulsions, the deeper one may be a low speed cubic emulsion, while the outer one may be a predominantly tabular one. Each emulsion may have a different LIRF and a different spectral response, so from it we can expect some change in the same way some an also multilayered color film can have color shifts when LIRF stressed.

[barnacle]

I might expect - absent further information - that B&W film might be somewhat more sensitive to blue than red light at very long exposures, simply because blue light has more energy than red. I'd *guess* that you need fewer blue-frequency photons to sensitise the halides than red-frequency, but this guess is *not* based on any rigorous analysis or knowledge.

Neil

[Pere Casals]

I might expect - absent further information - that B&W film might be somewhat more sensitive to blue than red light at very long exposures, simply because blue light has more energy than red. I'd *guess* that you need fewer blue-frequency photons to sensitise the halides than red-frequency, but this guess is *not* based on any rigorous analysis or knowledge.

Neil


Hello Neil,

Your reasoning makes sense, but the thing may be very complex...

Let me show you two graphs from "A Manual of Advanced Celestial Photography" from two slide films, sensitometric 1 hour exposures for color slide film, see blue channel behaviour, one shows a clear blue loss of speed compared with green/red, the counter for the effect you point (Note inverted curve because it is slide film). The other one shows a contrast shift for blue, it gains or loses depending on exposure/density. It is color film, not BW, but we see a complex behaviour from single channel silver halide emulsions !

170911

170912




Also with Velvia we have a Green shift and not a Blue shift with long exposures...

Well, here we compare emulsions from different layers, that can be different, not same emulsion for different color, but in these particular graphs we see same behaviour for Green and Red, so IMHO there are some complex effects that are not easy if not analyzed by a photochemical engineer knowing the particular emulsion tricks...

[Drew Wiley]

B&W films absolutely can shift in spectral sensitivity as well as contrast over long exposures. But you can't make a generalized statement about it. Even TMax 100 and 400 differ in this respect. Lesser quality films might even differ per emulsion batch. I did a lot of testing and curve plotting a few years ago regarding this very question. When in doubt, do your own specific tests under anticipated circumstances. As far as color films go, Fuji Astia 100F was the most predictable. Their CDUII duplicating film was simply a tungsten-balanced version of the previous Astia. Nothing comparable on the market today, though Portra 160 seems quite predictable under relatively long tungsten exposure.

[Jac@stafford.net]

For digital, there was the Leica M Monochrom with sensor with no bayer tiles, this is an exception.

Leica limits long exposure time and forces an equal time post-exposure black frame to map hot spots. Leica sucks for long exposures.

[Steven Ruttenberg]

Might want a long exposure for effects on water, clouds, moving subjects? Or to have a scene where the people walking through don't show at all because they are not there long enough to register on film?

Also when taking night photos like in the city of bldgs and such or astrophotography where long exposure with tracking are required.

[Steven Ruttenberg]

I don't know what Nikon DSLR you have, but the exposure on digital using the base ISO at a reasonably equivalent aperture for depth of field and with no reciprocity issues of course would probably be much, much less time. Consider that the Milky Way can be reasonably captured with a 10-20 second exposure with a reasonably bright lens and ISO 400 or so on digital. I've shot in very dim abandoned places with my DSLR and not needed more than 30 seconds of exposure.

Your experience with long exposures and such on film may trump the ability to do the same on digital. More importantly in my view is that sometimes I want longer exposures on digital but need ND filters to achieve them due to the higher sensitivity and wider f/stops in general use before diffraction.

I have taken 8 minute exposure with my 5DMKIII and the firefly convention was insane. As was thermal noise and tat was at base iso for Canon. It was also dead of summer in AZ and temps were like 110 degrees. So film I think would do better, evenif exposure needed to be 30 minutes.

[Corran]

Yes, digital cameras with 1 minute or longer exposures have issues, but multiple exposures + stacking and blending are the solution. More to the point, what I was saying there is that a 30 minute exposure calculation on film when likely at f/22 or smaller and accounting for reciprocity failure on a 64 speed film does not mean you need 30 minutes on digital. The darkest nights I have shot I still generally only use 30 second exposures at wide stops. It's also important to note that using base ISO is not a necessity. noise and DR is just fine on my D800 at ISO 400. So considering that you don't need and should not stop down as much on digital for similar DOF at a given field of view compared to LF images and have no reciprocity issues, a 30 minute image on film might only need 30 seconds or a minute on digital with proper settings. That's all I was saying. I have never needed an 8 minute exposure. If you are using a tracking mount you can stack 30 second exposures all night with no issues, as is standard.

Jac is right though, Leica digital sucks really bad for long exposures!!!

[Steven Ruttenberg]

It is interesting to note that film photography is immensely more technical than digital. If you could do away with bayer filter so you have 100% rgb channels and a luminosity only channel and make the sensor atleast 4x5 at a reasonable cost. You might have something, but also need to radically reduce thermal noise and other noise types inherent in a digital sensor.

Since this won't happen in my lifetime, and the fact that I like film for its artistic qualities and skill it requires to be a master at it. I will stay with film. I will still produce art with my digital rig as well, but I prefer film.

[LabRat]

Hello Neil,

Your reasoning makes sense, but the thing may be very complex...

Let me show you two graphs from "A Manual of Advanced Celestial Photography" from two slide films, sensitometric 1 hour exposures for color slide film, see blue channel behaviour, one shows a clear blue loss of speed compared with green/red, the counter for the effect you point (Note inverted curve because it is slide film). The other one shows a contrast shift for blue, it gains or loses depending on exposure/density. It is color film, not BW, but we see a complex behaviour from single channel silver halide emulsions !

170911

170912




Also with Velvia we have a Green shift and not a Blue shift with long exposures...

Well, here we compare emulsions from different layers, that can be different, not same emulsion for different color, but in these particular graphs we see same behaviour for Green and Red, so IMHO there are some complex effects that are not easy if not analyzed by a photochemical engineer knowing the particular emulsion tricks...

Hey Pere, I see that you have been quoting that book I suggested to you... Interesting, isn't it!?!! A lot of stuff not covered elsewhere...

Sad that this stuff is becoming lost knowledge, but read on, and keep it alive!!! ;-)

Steve K

[Corran]

I disagree - it's just different, and requires different techniques and handling.

I see folks who've shot film for decades say all the time that digital is too technical and then I hear younger photographers who've never really shot film say that film is too technical after hearing about typical film workflow. It depends on what you've grown accustomed to and how much there is to learn on the reverse.

[Pere Casals]

Hey Pere, I see that you have been quoting that book I suggested to you... Interesting, isn't it!?!! A lot of stuff not covered elsewhere...

Sad that this stuff is becoming lost knowledge, but read on, and keep it alive!!! ;-)

Steve K


Hello Steve,

I give you thanks again for that recommendation. It has been a very importante reading to me.

I learned about photography technique, but I also discovered how human understanding of the universe evolved since heliocentrism to present astrophysics in the last 1 and 1/2 centuries.

In fact it was silver photography (and LIRF control) what allowed an impressive leap forward in the universe understanding, as very long exposures allowed to discover and to understand celestial objects that were impossible to see by eye, being the workhorse of the most advanced astronomy until it shared relevance with radiotelescopes. Of course today digital imaging is used, but astrophysics has walked an amazing silver trail.

At first I was going to read only certain chapters, but I ended reading the all entire brick :)

[barnacle]

Regarding easy and hard for photographic vs digital workflows: I was a BBC engineer for over thirty years, from the last of the four-tube cameras until well into the digital age; while working with film at the same time. I'm pretty well acquainted with the technical limitations of both (as well as of the issues of digital compression, sampling, and data rate changing/rescaling). As suggested above - neither is better than the other, neither is harder than the other, neither is easier... but they *are* different.

And as with (say) analogue versus digital audio, the difference is *always and only* "which flavour of non-linearity do you prefer".

Neither analogue nor digital images provide a 'perfect' representation of the image, but both have different ways of attempting it. Much bollocks is written and spoke about which is preferable, but it all comes down to which you prefer: the workflow, the longevity, the image manipulations, and most important the final image which you prefer.

For me, I like the *process* of large format photography, simple as that.

Neil

[Jac@stafford.net]

I disagree - it's just different, and requires different techniques and handling.

I see folks who've shot film for decades say all the time that digital is too technical and then I hear younger photographers who've never really shot film say that film is too technical after hearing about typical film workflow. It depends on what you've grown accustomed to and how much there is to learn on the reverse.

One factor concerning preference is our age. Digital imaging did not exist when I was young with a pliable brain, when learning was easier. :) Today at a young 71 years-old I just imagine I'm okay with bits.

[Corran]

But Jac, 8-bit, 16-bit, or 24-bit? Or perhaps 32-bit floating point?? ;)

[Rich14]

Hold on, what about 2 bits, 4 bits, 6 bits a dollar . . . ?

Rich

[Jac@stafford.net]

But Jac, 8-bit, 16-bit, or 24-bit? Or perhaps 32-bit floating point?? ;)

I started with programming 16-bit systems in the Seventies. I am still comfortable with 64-bit. No big deal.

[Steven Ruttenberg]

It is interesting to note that film photography is immensely more technical than digital. If you could do away with bayer filter so you have 100% rgb channels and a luminosity only channel and make the sensor atleast 4x5 at a reasonable cost. You might have something, but also need to radically reduce thermal noise and other noise types inherent in a digital sensor.

Since this won't happen in my lifetime, and the fact that I like film for its artistic qualities and skill it requires to be a master at it. I will stay with film. I will still produce art with my digital rig as well, but I prefer film.

I say the above after having shot digital for almost 14 years now. Before that roll film and medium format once. Even though I learned on film, I never took the time to understand film and light. It was all by trial and error. Going back to film after 14 years digital, I can comfortable say film is a lot more technical and even though both digital and film photographers should understand light, etc, digital makes it easy to not understand. With a little bit of reading, and understanding what the histogram tells you, you can rattle of a half dozen shots and one will be good exposure wise. Then go to photoshop and further "fix" mistakes or oversights due to a lack of basics and unless your totally not artistic in the least, you can get a workable image. Therefore, I say digital is a whole lot easier than film.

Where digital is forgiving 99.9% of the time, film is not. You have to get everything right the first time, 2nd at most. Even if your not wanting to learn that much the economics of it all forces you to learn all you can. Plus, film still has better resolution. As an example on my 4x5 with a 75mm lens I get an 80.5 degree field of view on the long side, for 36mm sensor I get 27 degree field of view.

As you know, to get the same field of view requires a 21mm lens, but at the expense of resolution and more distortion to deal with post. Even with a tilt shift lens, which I have 2 of for my 5DMKIII, the 17mm and the 45mm, now three new tilt/shifts to get, but I digress, you get only a limited subset of movements, and they are a little more awkward to use, but same principal.

The 4x5 has total control and you can do things with it that are almost impossible to do with a full frame digital or almost any other digital. But even doing so, you are left with a much smaller field of view for a given focal length, to keep resolution leading to panoramic shooting, or sacrifice resolution for getting the same field of view. Don't get me wrong, I love digital, but it is a tool like any other tool. Right place, right time.

[Paul Kinzer]

I'm impressed with all the workarounds that digital astrophotographers now use. For just one example, thermal noise can be dealt with fairly easily by taking a series of dark frames that record the noise with the lens cap on, at the same settings as the 'light frames'. The noise can then be subtracted using software.

People are taking fantastic images even from highly light-polluted areas by using filters that block all but a very narrow set of color wavelengths given off by objects in the deep sky, thus blocking the pollution. This necessitates extremely long total exposure over, often, many nights. Hours and hours of exposure.

Stitching together digital image 'tiles' has also taken care of the resolution edge that film has. I've done some of these things, but am not at all skilled.

[Pere Casals]

For just one example, thermal noise can be dealt with fairly easily by taking a series of dark frames that record the noise with the lens cap on, at the same settings as the 'light frames'. The noise can then be subtracted using software.

DSLRs also do that, even entry level, for example Nikon D3200 does it, just set Shooting Menu -> Noise reduction option to ON, it takes a second exposure of same duration with the shutter closed and firmware substracs that dark shot. It is done in camera.

https://forums.cameratips.com/discussion/2844/nighttime-photography

[Paul Kinzer]

Right, but some of us do it out of sequence in order to take advantage of getting photons on the sensor instead of having to wait through equal amounts of light and dark while shooting. The ambient temperature of the surroundings can effect things, though, so if the temperature is falling as the night goes by, as it typically does, you cannot wait too long to take your dark frames. You also do not necessarily need a dark frame for every light one. It's been awhile, but I would often have the camera take dark frames while I was slewing my setup to a new target. If I had taken, say 20 two-minute light exposures, I might do eight darks with the lens cap on.

Some folks do not even do this anymore because newer cameras have gotten so good at controlling noise in many ways. Higher ISOs can be used, so shorter exposures are possible, so thermal noise (which is already much lower anyway) is avoided.

[Paul Kinzer]

Here's an image I made a few years ago, of M27, the Dumbbell nebula. It's a combination just like I described: about 20 30-second exposures through a 10-inch f/4.7 Newtonian reflector telescope, and ten or so dark frames at the same settings, combined in a freeware program called DeepSkyStacker. It is nothing like as nice as others out there, but I like it because I did it myself, on my driveway, through a telescope I built in my garage.

171148

And, to keep this post on-topic, here is a film image. If I recall correctly, it was 20 minutes on Fuji Provia 400f through a Nikon F with a 50mm lens, 'piggy-backed' on an inexpensive telescope that had motorized tracking to counteract the spinning of the earth.

171151

Each was challenging in its own way, but the film version was not entirely done by me, since I did not develop the slide myself. The waiting for the film to be returned, while hoping nothing went wrong with the tracking, was part of the 'thrill', if you want to call it that. Notice the definite magenta cast to the image. This is after trying to tone it down digitally. The biggest challenge for the second shot was twenty minutes of tracking, using an eyepiece in the telescope with cross-hairs to keep things perfectly centered.

There is something about astrophotos on film that I like better than digital. At least on the ones I've taken myself. The stars themselves seem more real, for one thing. On the higher resolution version of the film image, I can zoom way in and still see distinct pinpoint stars, very dim, but there. Digital images (and not just mine) seem to often overblow brighter stars before registering the 'tiny' dim ones (which are not actually tinier than bright stars, since all stars are just points of light through even the biggest scopes; these seemingly smaller stars do not look nearly as much that way except in photos.)

[Pere Casals]

Here's an image I made a few years ago, of M27, the Dumbbell nebula. It's a combination just like I described: about 20 30-second exposures through a 10-inch f/4.7 Newtonian reflector telescope, and ten or so dark frames at the same settings, combined in a freeware program called DeepSkyStacker. It is nothing like as nice as others out there, but I like it because I did it myself, on my driveway, through a telescope I built in my garage.

171148

And, to keep this post on-topic, here is a film image. If I recall correctly, it was 20 minutes on Fuji Provia 400f through a Nikon F with a 50mm lens, 'piggy-backed' on an inexpensive telescope that had motorized tracking to counteract the spinning of the earth.

171151

Each was challenging in its own way, but the film version was not entirely done by me, since I did not develop the slide myself. The waiting for the film to be returned, while hoping nothing went wrong with the tracking, was part of the 'thrill', if you want to call it that. Notice the definite magenta cast to the image. This is after trying to tone it down digitally. The biggest challenge for the second shot was twenty minutes of tracking, using an eyepiece in the telescope with cross-hairs to keep things perfectly centered.

There is something about astrophotos on film that I like better than digital. At least on the ones I've taken myself. The stars themselves seem more real, for one thing. On the higher resolution version of the film image, I can zoom way in and still see distinct pinpoint stars, very dim, but there. Digital images (and not just mine) seem to often overblow brighter stars before registering the 'tiny' dim ones (which are not actually tinier than bright stars, since all stars are just points of light through even the biggest scopes; these seemingly smaller stars do not look nearly as much that way except in photos.)

M27, you were capturing light born some 1360 years ago, the roman empire fell two centuries before, Visigothic Kingdom was rulling where I'm living... then those photons you catched started a trip from the all nebula places to your camera...

...just entering through the 10" hole of the 1200mm...

[Pere Casals]

171148


M27, you were capturing light born some 1360 years ago, the roman empire fell two centuries before, Visigothic Kingdom was rulling where I'm living... then those photons you catched started a trip from the all nebula places to your camera...

...just entering through the 10" hole of the 1200mm...

[barnacle]

There are a number of points regarding digital noise which are being conflated here.

If you add multiple images together, the light-generated signal, which is (nominally) constant increases linearly; the random electronic noise (thermal and shot noise) are added as the sum of their square root values - so when the final image is scaled, the noise is reduced with respect to the desired light. This increases the signal to noise ratio (higher is better) by 3dB for each doubling of the number of images being stacked.

Sensor noise - pixels with a fixed non-zero dark value - require a black frame which can be subtracted from the finished image since they will act as point souces. Since they are also subject to thermal noise, you should also use multiple dark frames to average that noise down.

Neither of these are issues with an emulsion (though it has other issues which I discussed earlier).

Neil

[Pere Casals]

There are a number of points regarding digital noise which are being conflated here.

If you add multiple images together, the light-generated signal, which is (nominally) constant increases linearly; the random electronic noise (thermal and shot noise) are added as the sum of their square root values - so when the final image is scaled, the noise is reduced with respect to the desired light. This increases the signal to noise ratio (higher is better) by 3dB for each doubling of the number of images being stacked.

Sensor noise - pixels with a fixed non-zero dark value - require a black frame which can be subtracted from the finished image since they will act as point souces. Since they are also subject to thermal noise, you should also use multiple dark frames to average that noise down.

Neither of these are issues with an emulsion (though it has other issues which I discussed earlier).

Neil

There are ways to solve all that. For planets a nice approach is using video cameras at 20 to 50 frames per second and stacking some 1000 images.

It is explained here:

http://www.skyandtelescope.com/astronomy-resources/astrophotography-tips/redeeming-color-planetary-cameras/

I'm a user of Point Grey cameras for machine vision applications, I've been using the Flea 2 model a lot, in this example he is using the later Flea 3 model.

This way it also allows to get a very wide dynamic range, as we can even generate a 24bit per channel image is we want, from addition of component frames, of course with much lower effective bits per channel, but with no clipped bright point.


Film has other problems... today film is not very common in astronomy, still great photographs can be taken !!!

[Serge S]

Every tool is different. We as photographers need to know what to use and when.

Yes! Plus we have so many options to choose from.
Different tools offer different approaches and shape how we work as well.