Silly Film Testing Mistake

[Michael Heald]

Hello! I could kick myself!
I've been using TMax 400 and TMax RS 1:3 at Room Temp with a Unicolor Drum. 135cc of developer does nicely for 4 sheets.
I wanted to give 75F and 1:9 a try, so I ordered the BTZS film testing kit of 5 sheets. I got a nice curve, but for some reason the negatives always looked thin to me.
As I reviewed my setup, I discovered that I developed the BTZS sheets individually in 135cc of 1:9 instead of having 4 sheets in the drum as I do normally after shooting. Looks like I exhaust the developer when I develop 4 sheets which was not taken into account when I developed the BTZS sheets individually!
Chalk this up under the LF mistakes thread.
I'll have to increase the developer amount by a factor of 3 in the drum, or redo the test. Oh well. Best regards.

Mike

[Donald Qualls]

Aaah, the old "minimum developer requirement" foul-up. I've even been caught by that one, trying to do 6 sheets of 4x5 in 250 ml in a tray, using a dilution that's perfectly fine for 4 sheets. When the highlights are thin, you know there's something causing underdevelopment...