Zone System Testing Mystery

[Michael R]

This is puzzling. I have never seen densities of low exposure values move around like that with changes in development time. Usually Zone I will move by 0.01 or maybe 0.02 with these changes but to me something strange is going on here. Those swings are huge. For what it’s worth some years ago I did extensive Delta 100 / DD-X testing and didn’t observe this behaviour and didn’t get these kinds of high contrast results. Delta 100 / DD-X should easily give N, N-1 without having to change dilution to lengthen development time. Maybe something has changed since then. In order to diagnose further we’d need to look at both the exposure methodology (and processing) in detail. I didn’t really understand the exposure target etc.

In the meantime I agree it would be wise to print some of these samples to see what they really look like in case the measurements are incorrect.

[mward]

Antonin, I am agitating, 2 inversions every 30 seconds. Easy inversions, not whipping the container back and forth. Continuous for the first 30 seconds.

Doing a paper test today I found that a negative density of 1.41 is a nice zone 8 on the paper grade 2. Luckily that's .15 over what my zone 7 measured so I'm gonna go with 6.5 minutes. I will test Antonin's times for n-1 and n+1 but so far he's been right on the money.

I printed one of the negatives that wasn't a test, it looks fine. I wouldn't consider it a serious picture but it was easily printable.

At this point I can at least get usable negatives, however, I will pack my densitometer to go with me, just in case.

Michael, I agree, this makes no sense based on what I know.

[mward]

The last time I really did this I was doing a masters degree in photography. I had a jobo, using tmax in tmax rs. My close friend had done the John Sexton workshop the year before and had plenty of advice. I had no problems. I did Sexton's workshop the next year. With regards to this stuff, I know what o'clock it is. I'm just a little rusty and working with new materials, new equipment, and it's behaving in unexpected ways.

[Vaughan]

I shot a scene, not a grey card. I stuffed a piece of velvet in the wheel well of my white truck, that way I can cheat and get a zone8 exposure at the same time...

Could be lens flare. That's a tough test for multi-coating.

[mward]

Could be lens flare. That's a tough test for multi-coating.

If we can't shoot a scene with zone 3 and zone 8 in the same shot what are we doing with our lives? We should quit photography. Lens was a Sironar N.

My tests after that were a different set up but I seriously doubt it was flare.

[bmikiten]

Lens flare is generally .05 or less even on uncoated lenses unless you are shooting into the light source.

[Vaughan]

If we can't shoot a scene with zone 3 and zone 8 in the same shot what are we doing with our lives?

The test setup for lens flare is a box painted white, with a hole in the front and the inside of the box painted black. This sounds functionally equivalent to a piece of velvet stuffed in the wheel well of a white truck.

[bmikiten]

Time to go back to the basics of film development and exposure. Expose for the shadows (Zone III or IV depending on who you follow) and change development to bring the highlights with detail into the proper exposure range. All this talk about velvet and white trucks is way off base.

[wattsie]

Possibly try a different batch/box of film?

[Oslolens]

If the temperature reading was of by 10F / 3,9C, it would look like an over exposure of two stops.

The explanation is often the most simple.

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