Chimping photos and reciprocity

[Disaster_Area]

I'm planning on doing a long exposure shoot downtown this weekend (lots of neon lights and such) with my Rollei and some 64 asa slide film I'm planning on cross processing. I want to chimp some shots with my DSLR to figure out exposure times but I'm wondering how this will work. Does anyone know if digital camera's suffer from or account for reciprocity? Say I take a shot and it looks good and my DSLR exposes for 4 seconds. Will the same aperture and shutter speed work for my Rollei or will I have to double the exposure to 8 seconds to account for the fact I'm shooting film now? If I where shooting B&W I'd just overexpose a bit and hope for the best, but I'm shooting slide film which A) costs more to develop (I do my own B&W) and isnt as forgiving exposure wise, especially with overexposing.

Anyone have any experience in this area?

 

[Chris101]

I suspect you mean 'reciprocity failure' as reciprocity means the more light you give a subject the darker the (b&w) negative becomes. Reciprocity failure is when the linear relationship of exposure to density becomes non-linear. If a 1/60th exposure gives a density of say 0.2, then a 1/30th exposure for the same light should give a density of 0.4 - the change is proportional.

When reciprocity fails, it's like a half second exposure gives a density of, say 0.5, while a one second gives 0.7. The relationship is not linear.

The simple answer to your question is no, digital cameras do not suffer from reciprocity failure. The relationship is linear no matter the exposure, until the photosites are saturated, then additional exposure does not change the value of the light at that site.

 

[crawdiddy]

I'm planning on doing a long exposure shoot downtown this weekend (lots of neon lights and such) with my Rollei and some 64 asa slide film I'm planning on cross processing. I want to chimp some shots with my DSLR to figure out exposure times but I'm wondering how this will work. Does anyone know if digital camera's suffer from or account for reciprocity? Say I take a shot and it looks good and my DSLR exposes for 4 seconds. Will the same aperture and shutter speed work for my Rollei or will I have to double the exposure to 8 seconds to account for the fact I'm shooting film now? If I where shooting B&W I'd just overexpose a bit and hope for the best, but I'm shooting slide film which A) costs more to develop (I do my own B&W) and isnt as forgiving exposure wise, especially with overexposing.

Anyone have any experience in this area?

I think the failure of reciprocity is not constant for all film emulsions. Each would likely have its own unique characteristics.

 

[Chris101]

I think the failure of reciprocity is not constant for all film emulsions. Each would likely have its own unique characteristics.

I think so as well. There used to be a fat volume called the Photo Lab Index that had all that information for just about every emulsion made all in one place. Unfortunately it is no longer published, so you will need to consult the manufacturer's literature on the film you are planning on using. And of course, cross processing may have an effect.

I'd suggest experimenting prior to shooting something the MUST come out on the first try!