Reciprocity and development

[mark]

I had my knee replaced 3 weeks ago. Since I have a lot of down time I am reading as much as I can when the pain meds allow it. I have spent the last couple days with reciprocity; a subject that has confused me from the beginning of my photo experience.

I understand what reciprocity is. I understand what it does and the reasons. What I can’t find is the development side.

How does a person know how much to shorten development?
Is there a standard or is it film dependent? How would one go about figuring this out if it is film dependent?

 

[rpavich]

I had my knee replaced 3 weeks ago. Since I have a lot of down time I am reading as much as I can when the pain meds allow it. I have spent the last couple days with reciprocity; a subject that has confused me from the beginning of my photo experience.

I understand what reciprocity is. I understand what it does and the reasons. What I can’t find is the development side.

How does a person know how much to shorten development?
Is there a standard or is it film dependent? How would one go about figuring this out if it is film dependent?

I don't think development even plays into it. It's only for putting extra light to the film to get a correct exposure.

 

[RalphLambrecht]

I had my knee replaced 3 weeks ago. Since I have a lot of down time I am reading as much as I can when the pain meds allow it. I have spent the last couple days with reciprocity; a subject that has confused me from the beginning of my photo experience.

I understand what reciprocity is. I understand what it does and the reasons. What I can’t find is the development side.

How does a person know how much to shorten development?
Is there a standard or is it film dependent? How would one go about figuring this out if it is film dependent?

I'll try to answer as simply as possible:as you know, the effect of reciprocity failure must be compensated through increased exposure either by increasing light intensity or exposure duration. This can create verydense highlights in the negative, which in turn can be compensated for by a reduction in development time. Using Zone-System techniques will give you a starting point for compensation values but as reciproityfailure is film dependent, only controlled testing will lead to accurate results.attached is the table I use for my films.

 

[Old-N-Feeble]

shoot Acros = problem solved

 

[mark]

@RalphLambrecht thanks. It seems that reciprocity exposure compensations are quite well known for most if not all films.

It seems to me there should be an idea of where to start the development. Does the development time decrease further as the exposure time increases?

 

[Rudeofus]

Low intensity reciprocity failure will lead to increased contrast and reduced film speed. If you compensate increased contrast with reduced development, you will correct contrast but lose yet more film speed. In my opinion you should not reduce, but actually increase development to at least somewhat compensate speed loss. Subject matter, which causes low intensity reciprocity failure, typically screams for highest possible film sensitivity, whereas excessive negative contrast can be trivially compensated with lower paper grade (or digital correction if you have a hybrid work flow).

If you self mix and want to clamp down on contrast without losing film speed, you could look at Michael R's speed preserving low contrast developer formulas. Don't get carried away by the first post in this thread, there are much less toxic and equally capable versions of this developer further down.

 

[Rudeofus]

PS: reciprocity failure is in the latent image, e.g. all developers will behave the same, regardless of whether that particular latent image was created by low intensity exposure or a photographically equivalent normal intensity exposure. AFAIK there is no such thing as a developer which specifically reduces effects of reciprocity failure, just developers with a more suitable characteristic curve.