It may help the discussion to illustrate what David is referring to, since it also pertains to the other thread about shadow detail and Bill's interest in distorted contrast for midtone placements with maximum expansion.

Attached is a no/low flare characteristic curve for CMS 20 (another document/micro film). Note Tech Pan was a little easier to "tame" than some current microfilms. This particular curve was part of an attempt to establish some baseline characteristics to which I could compare the results with low contrast developers and alternate dilutions of compensating developers. This was a while ago so I will have to look for the other charts.

As for getting a more useable tonality overall, and slightly more speed, I found TD-3 (a Catechol developer) gave the best result. Interestingly that developer also worked quite well with Tech Pan - and I believe it was originally formulated specifically for Tech Pan. Certainly it worked better than POTA and Adox's Adotech when it comes to uniformity. I wanted to try dilute FX2 but never got around to completing the tests on this film because I knew I wouldn't use it anyway. I was just curious.

Low contrast developers flatten the curve but also limit the maximum densities so while you can get continous tones out of them, you will never have as long an exposure scale as a general purpose film. That is the point to keep in mind. So, assuming you want to use one of these films for its resolution and lack of grain, I would suggest the following:

1. If you want shadow and highlight detail, use for relatively short scale subjects with a low contrast developer and/or low contrast development technique.
2. If you want maximum expansion of a short or very short scale subject, use with a range of developers from compensating to general purpose.

In my opinion, big time expansions or distorted tonality without golf ball grain are the reasons to use these films. Although many would disagree with me, I don't think they are very useful in general photography for making prints from small/medium format negatives look like they were made from large format negatives. To my eyes that simply doesn't work. You get fine grain but that's all. And you sacrifice much in the way of tonality. Put simply I have never seen a print from a microfilm negative that didn't look exactly like it was made from a microfilm negative. Film speed is another potential issue. Tech Pan actually had a semi-workable film speed depending on how you developed it. But its spectral response was rather odd and speed could vary substantially depending on the lighting.

Anyhow, just some thoughts. If I can locate the other curves I'll post if there is interest.

Michael