View Full Version : Rating Paper ISO - An Exact How To?

17-Jan-2011, 10:46
Hi all. I'm working on developing a workflow for using paper negatives in-camera and one of the things I keep running into are statements regarding the ISO rating of paper vs the ISO rating of film. Many people say that the best thing to do is simply test for your in-camera paper negative ISO. The problem is that I've seen this recommendation everywhere but no explicit instructions on how exactly to do it. Can someone PLEASE provide me with clear instructions (step-by-step) on how to test the in-camera ISO of paper? I understand there is probably more then one method so please share the method you've used. I am looking for a method that will give me the most exact ISO possible. I plan on using my Pentax 1 degree spot meter so plugging in the correct ISO is important for use with the zone system.

Please limit responses to information directly relevant to the question at hand with instructions on testing. Just trying to stay on track. Thanks!

17-Jan-2011, 12:14
Take a picture of a grey card metering off that then develop the paper and comPare it to the grey card

Jim Jones
18-Jan-2011, 08:09
Take a picture of a grey card metering off that then develop the paper and comPare it to the grey card

Better yet, bracket exposures of a grey scale. If you don't have a grey scale, set up lightly crumpled white paper for highlights and black fabric for the shadows. If you have an 18% grey card, include it for precise metering. Since paper tends to be contrastier than film, it may be difficult to record good shadow and highlight detail in one shot. Be consistant in developing these test images. The ISO of the exposure that suits you best is the one to use until experience suggests an adjustment.

Robert Hughes
21-Jan-2011, 12:37
Is the high contrast of paper a function of the paper emulsions or the developer?

21-Jan-2011, 12:44
Its more a function of the emulsion then the developer. Some people have some success with developing paper negs in exhausted developer to reduce the contrast but this is highly variable and isn't best suited for a workflow that requires a high degree of consistency and repeatability. However some will disagree with that statement as they find it very consistent and repeatable. The contrast of the paper is built into the emulsion. This is why graded papers were ideal for paper negatives. You could determine the iso of the paper and expose a few test sheets on different grades and dial in the contrast you wanted for your negatives. Variable contrast paper is different however because the paper is designed to react differently to different colors of light. Thats how you're able to control contrast on vc paper by using contrast filters.

27-Jan-2011, 18:01
To anyone interested, I've started a little blog on my website specifically for my experiments with paper negatives. This is the direct link to the blog (http://www.francescofragomeni.com/paper-negative-research/). Also, the whole reason I'm doing it is to be able to have readers look at my work and offer any advice or wisdom. Perhaps I might miss something or test for something unnecessary and a reader might be able to spot that and help me out. Gotta make use of this tool that is the internet! If you follow along with the experiments please contact me with any advice or comments, either by posting comments directly to the blog post or by email. Thanks!