converting color negatives to b&w digital files

[L Gebhardt]

I'm reading a lot about why it's better to shoot color film even if I want a b&w print...that I can get a color file and a b&w file from the same exposure by converting the color print to b&w in photoshop and still have the color file if I want it. But, somewhere in the back of my mind I seem to remember that b&w film has a greater tonal range than does color film. How about it...can some of your digital folks help me out?

It will depend on how you are printing. I generally don't like digitally done black and white on color paper such as what you get from a frontier or lightjet. I have yet to see a truely superb black and white inkjet print as well.

If however you plan on making contact prints or enlargements from a digital negative then color film will work just fine, and may be better than filters in the field on black and white. Just make sure you can get a decent color picture. Negative films, both color and b&w can capture a larger range than slide films. This is sometimes needed, but great results can be had with slide film in many cases.

Even though I have a decent scanner and can create digital negatives, I still prefer to shoot black and white film an print traditionally. I save the digital negatives for making contact prints bigger than the original film.

So to answer your question, it depends. I think you will need to try it to see how it works for you. Eventually you may get lazy and just decide sticking the negative in the enlarger, printing and developing is so much easier than the scan, edit and edit and edit, print, then contact print and develope route.

Good luck.

[sanking]

Well, this question actually has me curious about something. I've heard photographers go on about how using a digicam automatically gives you built in contrast filters effects if you isolate the image from one channel, say the red one, and only use that information in the monochrome version. While that sounds good, you would only be using 1/3 of the sensors and so I would think the resolution of the final monochrome image would suffer greatly, especially when compared with film. Or am I mistaken? Are the silver halide crystals uniformly sensitive to all wavelengths the film is sensitive to or are some doped to be red sensitive, others green-sensitive, etc., within the same film emulsion?

Joe

B&W films vary quite a bit in terms of their exact sensitivity to red, green and blue light. For example, Kodak Tmax films have slightly less sensitivity to blue light than other Kodak panchromatic films. The advantage of this, according to Kodak, is that the response of these films is closer to the response of the human eye.

For most practical work the color of the light used to expose the film has no impact on resolution. This is not absolutely true because blue light is capable of higher resolution in lppm than red light, but in practice you could choose for one reason or another to make your negative with a red, green or blue filter with little or no loss of resolution. Similarily, if you were to scan a color negative or color slide you could then choose to use all or just one of the color channels as a mans of controlling contrast, again with no loss of resolution.

If your goal is to make digital negatives it makes a lot of sense to use color negative film, especially in 35mm and medium fiormat. The color negative will give you a tremendous amount of control of color and contrast with virtually no grain, and of course you have the option of making either monochrome or color prints. When shooting medium format I use color negative film about 90% of the time.

Color slide film is much more difficult to work with, both in exposure and in scanning, and I don't recommend it if your goal is to make digital negatives.

Sandy

[smieglitz]

Thanks for the reply Sandy.

I don't think I phrased my question very well. What I'm wondering is if each grain of film in a specific emulsion has the same spectral sensitivity as the other grains vs. some grains sensitive to shorter or longer wavelengths. Does Tri-X have a bunch of blue-sensitive only grains and a lower proportion of red-sensitive only grains or are all grains uniformly sensitive to the entire spectrum. If the former, perhaps that could contribute to the lower film speed under tungsten light for Tri-X vs. Tmax for example.

I spoke of resolution in terms of losing 2/3 of the information by only utilyzing one of the RGB channels in a digital camera or image. I'm wondering if using a red filter with films has a similar effect in wasting a lot of the sensitivity by only exposing one flavor of dye-sensitized halides in a film. That would affect the speed but not the resolution. Or is it that the absolute intensity of light affecting a uniformly sensitive emulsion has been decreased by employing the filter, and so just less of them have reached their exposure threshold and reacted?

[steve]

All of the halide crystals in a B&W film are sensitized the same way, and there are not some grains more sensitive to one color than to another. Differences in spectral sensitivity have to do with emulsion formulation and how the emulsion is made panchromatic through the sensitizers.

Some people advocate the use of color film for B&W with scanning because some scanners have a "grain alaising" problem which is the scanner's dpi setting interacting with the grain of the film. You don't have that problem with either color film or dye based B&W films as there are dye clouds instead of grain.

[vet173]

Explore using channel mixer to get the tonal response and contrast you want.

[Joe Lipka]

Please don't tell anyone I am answering this question. It will ruin my already tainted reputation.
Should a person have a digital camera, they would be best to record in color mode using all possible sensors. Then, when they import all those bits and bytes into an image editing program, they can isolate the color channels and then, should they wish, they can pick the channel that best "represents" what B&W film would record. This has application to me in creating digital negatives.

Panchromatic film is sensitive to many wavelengths of visible light, Orthochromatic is sensitive to certain wavelengths of visible light. Infra-red film is sensitive to infra-red radiation.

[vet173]

If you really want to get into it, you can drop each channel onto the image as a layer. Then with mask and opacity settings you can really have control. That is if you don't mind having a multi gig file.