Deckled Edge said:
How about using a different piece of hardware for densitometry--a scanner?
[...]
Yep --- I've read a few accounts of folks using a scanner to do what I want to do. I'd just rather not have to start a project on a computer every time I want to read a print density.
Although I also want to measure dynamic range on finished prints, the specific thing that got me started on this is that I'm trying to get into a mode where I replenish my developer tray rather than dump it each day -- especially when I have several days in a row where I print. The thought of dumping developer that's still got a lot of capacity left, said developer being one of the major costs of a printing session, was starting to be a disincentive to doing a short print session.
I switched from a powder-based (Dektol) to a liquid concentrate (Ilford MG IV) developer, then filled up a 4x5 sheet film box with pre-exposed contact prints of a 21-step test wedge. I keep the first of these "test strips" developed in that chemistry as a benchmark, then at the end of each session, I cover the developer and fixer by setting a sheet of freezer paper on top, keeping most of the air out.
At the beginning of each session, I test the fixer with Hypo check and do a film clearing test, and I process one of my canned test strips. As the developer begins to get exhausted, the set of dissernable steps starts shifting to the left. At that point, I'll add 10-20 ml of and run another strip to get the scale back to the benchmark. (I use big 16x20 cement mixing tubs instead of trays, and use about 3L of solution in the developer and fix tray, and 4L of solution in my cheap-as-dirt single-use citric acid stop tray).
Right now, I'm just visually comparing the strips, but I'd like to get to the point where I can get the gamma from each one, plot trends and have a real controllable process. Yeah, I'm trying to reproduce what I used to do with roll film processors when I was in the Navy.
-KwM-