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I've been runnning some film processing tests of T-Max 400(8x10in.) with T-Max RS Dev.(1:9) using JOBO rotary processor, and I have some questions about the results.

First of all, Exposure Index which came out was 560. Is this pretty normal?? Here is how I found my EI. (I followed the article, "exposure test" in the KODAK book. 1. I set the manufacturer's recommended ISO film speed. That is 400. I exposed 5 sheets of film shooting a gray card (focus at infinity). 2. In the first shot I underexposed 3 stop so that the gray card is placed at Zone 2, and the second shot is -3 1/2 stops (Zone 1.5) , and the third is -4 stops (Zone 1), and so on. 3. I develop the films with T-Max RS (1:9) for 9 min at 75F using JOBO (rotation speed 3 1/2) 4. I read the density of the negatives. Base+fog was 0.06. The negative which is 0.16 was the one which was underexposed -4 1/2 stops. 5. I multiplied film speed(400) by the factor(1.4) on the article. 400 x 1.4 = 560 EI=560 Next, the result of the Development test shows that the normal dev. time is 10min. I set my new system-speed number(560), and shoot 4 sheets of films--which were overexposed 2 stops (Zone 7)and--process them in defferent dev. times, 8min, 9min, 10min, and 11min. The density of negative which is 1.11 was the one was deveoped for 10 min. 5. Thus, the result was EI 560 and 10 min development for grade 2 paper printing. Is this the right way to figure out?? Also, I read the article by J. Sexton about T-Max film ,and his current starting recommendatin for T-Max 400 in a JOBO with T-Max RS 1:9 at 75 degrees is EI 320 for 7.75 minutes and rotation setting on 3 1/2. My result is very different from his recommendation. So, I shot normal subject and processed both in my way (EI 560 for 10min) and in his recommendation (EI 320 for 7.75min) The negative processed by my deta looked OK whereas the negative processed by his recommendation looked a little flat in terms of contrast. Therefore, I thought that what he is saying in the article is that make a little flat neg. and add some contrast later when printing, which yield more beautiful print in stead of adjusting contrast when making neg. Am I misunderstanding completely?? How come my deta is away different from his recommendation?? I used sekonic meter and shunider lens --they are pretty new!! Anyone can help me?? I am beginner of large format. Thanks Anausagi

-- Anausagi (usagiana@aol.com), November 02, 2000


Anausagi, Fret not. You are doing fine. You have done the essentially the same thing that John Sexton has done - namely, tested yor materials and equipment to produce a neg. that works. If he had stood in your shoes and done the same thing, with the same equipment, he would have arrived at the same result you did. And conversly, if you ran his tests with his equipment..... No two imaging systems are exactly alike.

I seem to remember John Sexton writing some time ago that the Nikkor lenses that he uses are so contrasty that he has to hold back one step in his processing....might explain the flat neg.

Keep plugging, bw

-- Bruce Wehman (bruce.wehman@hs.utc.com), November 03, 2000.

I agree with Bruce that what you have done is to find your personal film speed according to density measurements. The difference in 400 ASA and 560 is less than one-half stop, so you are well within limits. You did not say if you have made prints. It might be that you will prefer to adjust the speed once you start printing. At least you have a base from which to make any adjustments you prefer.


-- Doug Paramore (dougmary@alaweb.com), November 03, 2000.

I'll bet what you're really seeing is that your shutter's running a little slow, shutter efficiency is down when using a small aperture and fast speed, and your meter may be reading a little off (assuming you used one)....or actually it's probably a combination of all of those things.

Contrast is a matter of materials used and taste; some like a delicate neg and some like a beefier neg. You're not doing anything wrong; you're finding what works for your equipment, methods etc. It would be wrong to simply use Sexton's exposure and development specs without testing for yourself.

So now shoot some real photos, make some real prints and adjust accordingly.

-- John Hicks (jbh@magicnet.net), November 03, 2000.

You've done your homework, now apply what you have learned. Wether 560 or 400 or 320, it doesn't really matter. Results are what counts. If you're happy with the way things are looking, stick with it.

-- William Levitt (light-zone@operamail.com), November 04, 2000.


Go with your test results. Make your prints, and do not fret aboyt sexton's results. Sexton will tell his workshop people that his tests are his tests. You could use them as a starting point, but you must personalize them as you have done. The lenses Sexton used, the meter-- he uses a Pentax Spotmeter. I know from experience that if I run tests using my Minolta Spotmeter F and my friend runs the tests at the same time at the same place using his Pentax meter that our results will differ!. But our prints look the same by the time we make the prints ide[pendently of one another. If you create adequate shadow detail and your highlights don't go off the scale, and your prints look fine. Don't worry. Bob

-- bob moulton (bobmargaretm@home.com), November 04, 2000.

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