Hello,

I just did a simple test placing shots of some textured fabric at different shutter speeds relative to the meter reading, with 35mm APX 25 and xtol 1+2. It seems that there is a bit too much density at zone 1 and too little at z 9, although I'm not going to go to the bother of a densitometer. There is definite texture present in both those frames. Does this mean that the combo is faster than EI 25, and the dev time is too short for the temperature used?

I developed according to the Kodak data sheet, 9.25 mins + 15% (300mL@1+2 per film)(rounded to 10 mins 30 seconds), @ 20C. I notice that the times in the data sheet vary greatly with temperature. Could the lack of contrast be due to cooling of the solution during development? I am thinking of trying it at EI 32 and deving for 12 minutes next time, with some more test shots... does this sound reasonable and is it likely to ruin any other shots I have on the roll? Or would it be better to keep the tank in a water bath during development, to avoid inconsistencies dependent on air temperature?

Thanks in advance from a newbie. Sorry for asking so many questions!

-- Russell Edwards (redwards@mania.physics.swin.edu.au), January 11, 1999

Answers

Yes, if you get definite texture (rather than 'just a tiny bit of texture') in zone I, and you are interested in the ISO film speed, it could be up to a stop faster than your initial guess.

The zone IX is harder to guess. I can't estimate higher densities without a densitometer. The fact that it shows texture doesn't mean you are underdeveloping. Without a densitometer, the best test is: how do your negatives print? If you normally need a grade 2 or 3, all is well. If you normally need grades 4 or 5, then you should increase development.

If your air temperature is much below 20 deg C, then the tank will cool, which will reduce development, and hence contrast. Is summer in Australia that cold? You can easily test this before your next film. Just fill the tank with water at 20 deg C, and take the temperature after 10 minutes. The average of the two temperatures is (pretty much) the effective temperature of development.

Yes, a water tank will stabilise the temperature.

-- Alan Gibson (Alan.Gibson@technologist.com), January 12, 1999.

Thanks for the replies. I did a gr 2 contact sheet once the negs dried fully, and the detail levels were about right. I suppose the fact that the neg can hold more contrast range than is printable on gr 2 paper, yet the gr 2 paper holds the 10 stop ZS range as recorded by the film OK just means that the film has a bit of extra latitude?

-- Russell Edwards (redwards@mania.physics.swin.edu.au), January 12, 1999.

Oh by the way, I live in the south of Australia in some hills near Melbourne, so it's often 5-10 degrees C cooler here than in Melbourne... I think it was about 14 degrees C when I did that film at about 9am :-)

-- Russell Edwards (redwards@mania.physics.swin.edu.au), January 12, 1999.