4x5 neg processing in homemade tubes

[Bob Salomon]

I spin the tubes like I think it shows in the video. I have six tubes. Spin the outer sets of two with a sort of pinching motion. When they are about to stop spinning, pinch the middle two to spin them. When they've about stopped, go back to the outer two. I just do that over and over, and I get nice even development.

I'd say decide how you are going to spin them, then do some tests using that spinning method to get your development times.

I am of the belief that any slight variation in my development method has far less effect on the end result than my exposure of the film.

Variations in your development control the contrast. Variations in your exposure effect the density.

[frednewman]

h2omen - Once you get your routine standardized for processing you should do a film test. You might check out our film testing service. With the service I expose the film to a 21 step - step tablet to a calibrated light source. Send the film off to you for processing - 5 sheets processed one each at 4, 5.5, 8, 11 and 16 minutes. You send them back to me for reading on my densitometer and then the densities entered into the Plotter program.

It makes film testing with the BTZS tubes only about an hour of your time for processing. I have some videos on youtube showing this. Just do a search on the word "viewcamerastore".

If you have questions please call or email me.

Thanks

Fred Newman

[Brian Ellis]

I used the service discussed by Fred three or four times and highly recommend it. When I did my own testing I used to go through many sheets of film and at least a couple hours of effort. Using Fred's service took less than an hour. Plus I received far more information than I could have created on my own, at least without buying the Expo-Dev program.

[h2oman]

Fred,

Thanks for the suggestion - I'll probably take you up on that sometime soon.

Bob,

I have at least a vague understanding of the difference between exposure and development. What I was trying to say is that I've made much larger errors in the field when determining exposure and development than in the actual mechanics of development, in general. Developing for 15 seconds + or -, or having my temperature off by a degree, has not seemed to cause me anywhere near as many bad images as just screwing up the initial exposure or making the wrong judgment about whether to use purposeful plus or minus development and how much.

Now for all of you who are for more experienced than I, here is what has frustrated me. When I try to read about determining exposure and development, much of the literature is geared toward traditional wet printing. The process described involves taking the testing all the way through to the printing stage. I'm scanning my negatives and then printing digitally. I know that many people do this, but about the only person I recall writing about it is Ken Lee, who said something to the effect of "If you take a scene with normal balance of tones (regardles of the range) and when you scan the negative you get an approximate bell curve fitting fully but comfortably in your histogram, then things are correct." (Subject to paraphrasing and a sometimes poor memory.) I've generally managed to take scenes with only two or three stops of contrast up to 5 or 6 stops and get negatives whose histograms look like that when I scan them. I rarely have to do reduced development, so haven't figured that out yet.

For that reason, and to perhaps validate or fine tune my other developments, it would be valuable for me to do Fred's test.