[jnanian]

That is a given. I'm beginning to see what Michael R 1974 was worried about. jnanian, when one conducts a scientific experiment everything is standardized and the only variables are the ones being tested or the ones that can't be feasibly elimnated. Furthermore as I mentioned previously everything is disclosed in detail in the materials and methods section of the published report. Even things like the film's lot number and expiration date are recorded in case the manufacturer later says they had a bad batch. There is no way you would let different people agitate the developing tanks unless they have already been certified as doing it in the exact same manner. As long as sufficient movement of fluid occurred the exact method of agitation is immaterial. What is important is that it is not extreme (shaking a martini), that it is done in the exact same manner each time, and that the exact manner in which it is done is documented. In today's digital world a short clip showing how exactly the agitation was done can even be placed on the web. At most the variables should be film, developer, and length of developing time... at least as far as the developing stage is concerned. Perhaps there are other variables that can't be eliminated that I am overlooking.

i was using extremes in differences in agitation methods as an example because people often times see photographs
and negatives &c and they literally think their film will look "just like that" if they process it in whatever magic soup they have.

Also I wouldn't use sheet film. That is not the most common type of film used. My inclination is to use medium format film because you still have a nice big negative to work with but it is still a roll film. Medium format film is great because it would be easy to set up your camera and just swap backs with different films. The problem is not every emulsion is made in medium format nor large format for that matter. So again to standardize 35mm across the board is the logical choice. Initially just to keep things reasonable the first experiment should just be with the top sellers at each ISO. But it's nice to standardize on 35mm in case one desires to do future experiments on funky emulsions only available in 35mm.

does it really matter what format the film is? film is film is film. tri x 400, hp4, hp5, tmx fomapan, &c are exactly the same ... it is just presented differently.

The problem is a lot of us don't do too much darkroom work. You will get a lot of scanned negatives. Scanners, at least of the cheap (<$1,000) variety are black boxes. I have no idea what my scanner does to the information it reads off of my negative so there is no way for me to make a negative to negative comparison. I think there is a software package that is at least capable of holding exposure constant from scan to scan. But the fact remains you still don't know what the exposure was to begin with.

Check out this site. I use it to see if what I am doing with a new developer is at least reasonable.

the problem then is that scanners don't really show the film and everything else. if someone had a light box and took a photograph of the negative with a numeric camera
maybe that would be better because at least it is what is there, not a reinterpretation of what is there, by a magical beam of light. and even then it won't really work
because sometimes film is so dense that a light box won't shine through it. ... morgan+morgan / morgan + lester used to do these exact same types of experiments,
their results were published in a tome called the photo lab index ... i was lucky enough to have a long conversation with the chemist who
did all the lab-work. he was a brilliant guy.

http://www.amazon.com/Photo-Lab-Inde.../dp/0871000512

the only thing the PLI doesn't have is photographs made with the developers and film. if you don't have a copy of it, maybe
you should hunt one down, it is a pretty good resource.