Alexandra Wesche

Hello all, during my research concerning relationships between density, filters, printer points and film stocks I keep returning to this topic to understand them. I understood the relationships between lense filters and negativ gamma, but I often also read that a 30ND filter at 0,025 Log E equals one F stop and 12 printer points. When is that the case? I also have a question concerning CC filter grading on a print and the translation into printer points. Brian writes above that, because of the contrast increase from negative to print CC filters can't be seen as 2,55 CC = 1 printer point. Do I understand the following correctly? A 30 CC/ND filter on a camera lense leads to a density change of 0,17 on a negative with the contrast of 0,55 and can be corrected with 7 printer points when grading for the print. That means 0,025 Log E on the printer = 0,025 density on the film. When (sight) grading with a 30 CC filter (I know that's too much) on a print, we have to include the contrast increase from negative to print. Which would mean 0,025 Log E on the printer = 0,07 density change in the film. The process is the same: a correction of the negative for the print. In the second case, do we have to calculate with 0,07 instead of 0,025, because we're judging the correction by the look of the print? Do I understand it correctly that 0,07 can only be used, if the density change in a LAD patch is actually exactly 0,07 for 1 printer point on a specific printer. What can I do if I feel that a print is only 1 point too magenta (or whatever) judging by the CC filters. Please excuse my complicated expression of this topic. I still have to think very hard to express these thoughts... I hope it's still somewhat understandable.

Thank you!

Thanks, I'm halfway through the site and Brian's book and I read your book, before I started working any practical work on film. Might be a good idea to reread it now... I'll look into the other one. Just out of interest... do you still use your method to copy tinted/toned films as opposed to the Noel Desmet method?

Unfortunately there are only daily wedge tests on the b/w negative process independent from the exposure of the film that is to be processed. The lab tests are pre-exposed by Kodak. To get the actual gamma of the b/w negative that I want to expose and process I would have to attach a wedge to the positive and expose it with the same light as the picture right? Where would I get such a wedge or would I have to produce it myself with the estimated gamma of the positive? Please correct me if I'm on an altogether wrong path.

Thanks a lot! Can I control the aim gamma of the dupe negative with grey patches attached to the positive? If so how many are reasonable and what densities should they have?

Hello all, I have no traditional film lab education and I'm trying to get my head around all things light, grading, sensitometry etc. I have read a lot and I've experimented a bit, but there are still many questions and noone to ask... Let's say I have an old b/w positive print and I want to transfer the contrast values as close as possible. How do I know which gamma value my original has and how can I measure the aim gamma of the dupe negative? I hope somebody can shed some light... I'm also grateful for any literature references (possibly not too mathematical). Thanks, AW