Film vs digital for long exposures

[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/pro..._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/pro..._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/produ...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?