View Full Version : densitometer settings

Allen in Montreal
20-Jun-2009, 17:31
I am in the process of establishing my film speed and dev times for Tri-x, the emulsion I am exposing now is the "new to me" TXP launched a few years back ( I had boxes and boxes of the original TXP in the freezer and have recently run out).

My pro lab has closed its doors and I am relying on a consumer lab to read the negs, the lab tech does not know how to do anything but a basic straight up RGB reading, which gives base fog readings of:

R .62 G .65 B .62

My estimated film speed based on eye balling it is 200 asa, which gave:

R .66 G .70 B .64

Is there any way to translate an RGB into old school gray scale readings or any advice to give the lab tech for settings on his densitometer?

phil sweeney
20-Jun-2009, 18:16
Hi Allen,

Typically you can use the blue reading or set the machine for vis (visual mode). Typical base and fog is 0.04 to 0.06 and speed would be 0.1 over. Have we overdeveloped our film?

Allen in Montreal
20-Jun-2009, 20:57
Hi Phil,

I will ask him if there is a "vis" mode on the unit.
The negs look pretty good and print well. Are they perfect, not yet, are they close to the mark, I would think reasonably close.

When I started to play with the newer TXP, I saw the suggested process chart and moved away from HC-110 B for the first time in my life. I have been testing D-76 at 1:1 in a Jobo 3006, exposing at 200asa and processing between 7 and 8 minutes.
I also bought a case of T-Max RS developer to test but have yet to try that.

My thought on the RS was, I have always liked the HC and perhaps RS could be as easy and consistent to use as well as John Sexton's comments about D-76 increasing in strength as the solution ages. Once I get a feel for D-76 at 1:1 I will do the same with the RS, try HC one more time with Richard Coda's starting points (despite Kodak saying NR) and then pick one and stick to it.

Allen in Montreal
24-Jun-2009, 19:55
Thank you Phil,

I stopped in and visited the lab, he found the "vis" setting and read the negs for me.
Now to test for dev time.

Ed Pierce
25-Jun-2009, 03:26
My experience with TXP in HC-110 is that dilution B is too strong, when developing 6 sheets of 4x5 in a tray with 1L of solution.