What densitometer with Pyro Negs?greenspun.com : LUSENET : Large format photography : One Thread
I would like to get very accurate development times for my film processing and thought that density readings of test strips would be the best way to go. I have read that one needs a densitometer that reads colour to obtain readings from a Pyro stained negative. What type of densitometer should I look for? There are several on ebay but I am unsure of what I need. Is there anything else I need to obtain the proper readings (filters, etc.)?
Many thanks for the help.
-- Matthew Hoag (firstname.lastname@example.org), April 15, 2002
Matthew, I got bogged down with alot of testing and stuff to the point of near insanity. I develop by inspection now and it is a very nice way to go. Not saying it is the only way to go but the preffered way for me. There are just so many variables to deal with it really makes sense. Why exercise so much control over everything and then not give yourself the chance to look at the neg with the most high tech testing device ever made...YOUR EYES!!!! Michael Smith has an excellent article on DBI at his web site michaelandpaula.com as well as Ed at unblinkingeye.com. It also gives you more time to spend making pictures! Good Luck
-- Michael Pry (email@example.com), April 15, 2002.
Pyro and densitometers don't like each other. You can't really get consistent, accurate readings with pyro negatives. The usual advice, which you've apparently seen, is to get a color densitometer and read through the blue filter but I have a color densitometer and that didn't work either. I kept getting different readings from the same points on the film. I originally thought there might be a problem with the blue filter on my densitometer but I've since read confirmations from people more knowledgeable than me that the blue filter doesn't solve the problem. So I would definitely not recommend spending the money for a color densitometer just so you can read pyro negatives.
-- Brian Ellis (firstname.lastname@example.org), April 15, 2002.
As other responders have said, it's hard to reliably read pyro negative because of the stain. The best way to adjust your ASA and development time with pyro is through experience with actual photographs. If you're not getting good tonal separations in the shadows, you're probably underexposing the negatives. On the other had, if you've got good shadow separations, but your prints are flat, you need to increase development. Or, if your highlights are blown out, you're overdeveloping and need to cut back. A couple of iterations should allow you to get things in line. Then you need to be consistent in exposing and developing. Good luck, pyro makes great negatives.
-- Jay Wolfe (email@example.com), April 15, 2002.
Jay, Wouldn't this apply to ANY film developer combination? Barry
-- Barry Trabitz (firstname.lastname@example.org), April 15, 2002.
If you want a negative that would read better and also stain use a Catechol based developer. I have an X-rite 810 and read my Catechol developed negatives with it and it is on the dot every time.
-- Jorge Gasteazoro (email@example.com), April 15, 2002.
Instead of a densitometer, buy a 4x5 step wedge. Contact print it on to the film of your choice (under your enlarger), and develop. If you've got a good range of exposure, you'll have steps from clear to very dense. Then put the negative in your enlarger with contrast set at whatever corresponds to neutral (all controls at "0" on a color head). Find the minimum printing time that gives you maximum black through the "clear" areas and make a print. Assuming a 1/2 stop step wedge, either the second non-clear step (on the negative) ought to be Zone 1. Count steps from dark to light (on the print) and see how many you get until you get to blank white paper.
This will tell you how many Zones you are covering on a normally exposed and developed negative. You can then decide if this is a good "standard" development time for you, or if you want to change it in some way. Zone X is usually assumed to be pure white.
If you're covering too many Zones (low contrast), increase your development time. Too much contrast, shorten the time.
No reason why you cant do a whole series of negatives and delvelop them for different times. Then you'll know the practical expansion and contraction limits of your film and developer.
Notice that this test won't tell you anything about film speed....just contrast range.
I like this method because you're testing your materials just the way you use them, in the enlarger making prints.
-- Kevin Bourque (firstname.lastname@example.org), April 16, 2002.
A few years ago I was given an upright stat camera with an onboard reflection/transmission densitometer and thought I'd use Phil Davis' testing methods to zero in on my PMK negatives.
After a couple of weeks of testing and frustration, I finally emailed Davis himself and he got back to me in a couple days to say that he too had not been able to successfully use a densitometer to test pyro negatives.
To me, the most useful testing method is a somewhat varied version of Steve Simmons' visual technique outlined in his "Using the View Camera" manual. Basically, I test for print tonalities that I expect from various measured subjects.
Most of my 8x10 work is now done in ABC pyro with a weak green safelight to inspect visually (thanks Michael A. Smith!). To me this is the ultimate control for large format, and once you get the hang of watching the highlights appear, a real pleasure to print using Azo paper.
-- David Haynes (email@example.com), April 17, 2002.