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swmcl
28-Jul-2014, 19:31
I am searching for a routine to do some testing that might not take so much film ...

Normally, I would either know from experience or I would come to a calculated guess as to the film ISO and development time for 'normal' development ('Normal' for me is to the CI of condenser enlargers - 0.47ish). I would shoot a roll of 35mm film in my Nikon of various exposures from -4.5 stops to maybe even 8 stops over my 'N'. I would then develop for the guesstime time and repeat for N-1, N-2, N+1, and N+2 etc. This would involve a roll of 35mm film for each development time and I'd like to have one sheet of film take the place of a whole 35mm roll basically.

I am trying to get an understanding of how to do it with a 4x5 step tablet and no enlarger. I do not have an enlarger nor do I have access to one.

If I jam the step tablet and a fresh piece of film into a holder and then use the camera as an exposure tool, could it be done? (Can a sheet film holder accomodate two sheets without damage?)

Do I just keep firing off a few sheets till I get most of the tones on the tablet onto the film at the guesstimated development time? From there I would then shoot off say 6 sheets to develop them differently?

It all seems rather haphazard...

At least with the Nikon I'd know the shutter speeds used for each exposure...

Bill Burk
28-Jul-2014, 19:48
I'd get a small piece of glass, say 5x7 inches... tape or file the edges so you don't cut yourself... Place the film, emulsion up with the step wedge, emulsion down, under the glass...

Then find a way to hit this sandwich with a specific, reproducible amount of light. Electronic Flash and Tungsten (with 80B filter) work OK as light sources. Trying to use the Sun is asking for trouble.

If that means taking the back off the Nikon and putting it on a cardboard box over a light bulb... so you can make a 1 second exposure to the film... Great. Anything.

Then develop the film and see if you got a range of steps from clear to black on the sheet of film. Looking at the negative, you can count the steps (assume half-stops each) from what you got to where you wish you had gotten... to decide whether the next exposure should be more or less. And you will know in terms of stops how far off you were.

Then, when you want to make a BTZS or other test, you Jerry-Rig this thing up and make 5 sheets with the test setup. You can dismantle it when you are done, if it's easy enough to reconstruct.

swmcl
28-Jul-2014, 19:59
Or maybe get a contact printing frame onto the back of the LF camera ... Has such a thing ever been made?

Onto your reply... supposing I was to get the exposure sorted to get a range of tones on the film ... How do I correlate that exposure to the one I'll use in the field? That comes through measuring the slopes again after development does it? (As in finding out the film speed from the tests themselves. Not worrying about how the light got onto the test films as such but that it got there in sufficient quantity...)

Thanks for your thoughts too BTW!

Kirk Gittings
28-Jul-2014, 20:05
Just pick up an old copy of Fred Picker's Zone VI manual and run the tests. The procedures will give you proper ASA and development for whatever system (tray, tube, taco etc.) you are testing.

Bill Burk
28-Jul-2014, 21:00
Or maybe get a contact printing frame onto the back of the LF camera ... Has such a thing ever been made?

Onto your reply... supposing I was to get the exposure sorted to get a range of tones on the film ... How do I correlate that exposure to the one I'll use in the field? That comes through measuring the slopes again after development does it? (As in finding out the film speed from the tests themselves. Not worrying about how the light got onto the test films as such but that it got there in sufficient quantity...)

Thanks for your thoughts too BTW!

For the exposure (film speed)... take it for granted that with fresh film, fresh standard developer, the sheet of film that gave you 0.62 contrast... Is BOX SPEED...

If the curves slip around, for example if your exposure times are hard to control, you can always take the contrast results for development time.

But if your exposures in the jig are consistent, then everything else, including any other developers, relates to that one benchmark sheet that hit the standard 0.62. Normally Zone System users develop to lesser contrast, like 0.5 contrast, so you will probably get a little less than box speed in the field.