B&W filters with chromogenic C41 film

seaninsurrey · Jun 25, 2007

I'm using Kodak CN400BW film a lot these days and was wondering if it is ok to use a yellow or red filter with it? Are the results comparable to when using regular B&W film? Thanks in advance.

Ole · Jun 25, 2007

It's just the same as any other BW film - only the processing is different.

use whatever filters you like, just as you ordinarily would.

srs5694 · Jun 25, 2007

I basically agree with Ole, although I'll add a caveat that I don't know how the spectral response of chromogenic B&W films compare to that of conventional B&W films. For all I know, the chromogenics could have greater or lesser sensitivity to {blue, green, red, whatever} light. If so, this could affect how a filter will work with the film, although it's likely to be a difference of degree rather than any really fundamental change. I do know that even conventional B&W films vary in spectral response. For instance, Efke's ISO 25 and 50 emulsions are less sensitive to red than are most other B&W films.

AgX · Jun 25, 2007

Yes, conventional B&W films vary in their sensitation.
But there is NO relevant relation between sensitizing and the kind of processing, in this case chromogenic development.

However Ilford employs for their ISO 400 XP2 the same `conservative´ sensitation they employ for their films up to ISO 100. Their conventional ISO 400 Delta 400 has a more extended sensitation.
Don't ask me why. It could be to divide their two films of the same speed more from each other, but then it should be stated more pronounced. Could be some technical reasons I can't imagine.

pentaxuser · Jun 25, 2007

AgX said:
Yes, conventional B&W films vary in their sensitation.
But there is NO relevant relation between sensitizing and the kind of processing, in this case chromogenic development.

However Ilford employs for their ISO 400 XP2 the same `conservative´ sensitation they employ for their films up to ISO 100. Their conventional ISO 400 Delta 400 has a more extended sensitation.
Don't ask me why. It could be to divide their two films of the same speed more from each other, but then it should be stated more pronounced. Could be some technical reasons I can't imagine.

Interesting point which I haven't seen expressed before.What are the practical effects of this extended sensitation in D400 compared with D100 and XP2 plus conservative sensitation?

Thanks

pentaxuser

Bill Mitchell · Jun 25, 2007

I routinely shoot XP-2 with a dark yellow (G, or #15) filter to approximate it's response more closely to how I see the world. For conventional films such as Tri-X I tend to use a medium yellow (K2) to correct for the difference. Nothing scientific, it just seems right.

AgX · Jun 26, 2007

Pentaxuser,

From a theoretical point of view the difference would either be at distinguished reds or at incandescent lighting. It should be within the range of CC filters. Test exposures of a colour chart should tell you more.

Christopher Walrath · Jun 29, 2007

I shoot TMax and BW400CN in 35mm and use filters with both and they seem to me to produce comparable results with my contrast control filters, though I get more blue and green seperation at faster shutter speeds. Filtered or otherwise.

B&W filters with chromogenic C41 film

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