I'm hoping someone out there has run into a similar problem and can offer some words of wisdom. I have been using Tri-X sheet film (4x5) and HC110(B) for some time and have had grood results. I had no problem getting the correct density for Zone I and setting up a personal E.I. I decided to start using my 35mm to shoot some B&W when I don't have time or space to carry the view camera. So, I figured I'd shoot Tri-X and use HC110(B). I know that the Tri-X Pro and the Tri-X 35mm are different, but I am having no luck getting the correct density. I started out with the usual film speed test, shooting a bunch of Zone I frames at different E.I. I shot a range from 800 to 200 in 1/3 stop increments. I used the recommended development time of 7.5 min at 68F. My densities were _way_ too high! They ended up in the range of Zone IV to Zone V! I figured I just screwed up in the test so I reshot. I got the same results, so at least I know the developing is somewhat consistent. I reshot one more time to be sure the guy behind the lens wasn't crazy. Same results. I looked high and low for development times, my old Kodak Darkroom Dataguide had a recommended time for Tri-X and HC110(B) listed around 5min. Odd I thought, did the film change at some point? I reshot the test, developed for 5min 15sec, I still come out with densities to high, although closer. If I were to use the 5:15 developing time I'd have a E.I. if 1600! ARGGG.

The meter used is my spot meter I used for the film testing for the Tri-X sheet film. I use Tri-X sheet film with a E.I. of 160 with very normal development times, close to Kodak recommended times. The meter in the 35mm agrees with 4 other 3 other meters, within 1/3 of a stop. So I'm sure that isn't the cause.

I'm running the tests with a Pentax LX, 50mm f:2. I don't think the lens, or the shutter is _that_ far off. I could accept a 1/3 or 2/3 of stop error, but not 2 stops!

Something is very odd, any ideas out there?

-Dean

-- Dean Jansa (jansad@cray.com), February 12, 1998

Answers

Try 6.75 minutes at 68F with a EI of 200. You mentioned how your tests looked but you did not mention how your film exposed to actual photographic subjects looked. If you test a roll of film with all Zone I exposures your developer activity will be too high for a realistic test. A couple of ways to test roll film is to test Zone I, V and VIII at the same time, another approach is to have only 4 or 5 Zone I and the rest of the roll be real pictures. Also I don't beleive it is necessary to be within 1/3 or 2/3 stops on roll film because your aperature won't always have small enough adjustments to get you that close anyway, just error on the side of overexposure within limits.

-- Jeff White (zonie@computer-concepts.com), February 13, 1998.

Thanks for the help, it turned out to be the sutter. The normal photos were also much to dense, so the LX is back getting its shutter taken care of.

-Dean Jansa

-- Dean Jansa (jansad@cray.com), February 16, 1998.