Determining Exposure for Enlargements on Film

[Bill Burk]

I have a couple “projects” that involve making an internegative from a black and white transparency.

There was a brief time when I enjoyed using Kodak Reversal Processing Kit with Panatomic-X so I have some black and white slides that I have never been able to print traditionally.

I also bought a pretty high quality slide of “Shantytown”, the first halfone printed in a US newspaper from a photograph.

Holding me back has been the awkwardness of handling film like enlarging paper and determining the exposure time.

Just now a possible shortcut occurred to me. I still plan to use 4x5 TMY2 for the internegatives. But I could do “test strips” in 35mm. Just set the camera on its back without a lens and use B setting for a series of times.

I can get the rough time as a starting point by using an ES-II without film and just use “Auto” and adjust until the time sounds like it’s somewhere between one and four seconds.

Note all the enlarger settings, put the film in and shoot a series at B with enlarger times in f/stop timer-type series (like 1, 2, 4, 8, 16 seconds) writing the times down as I go.

Then after developing the film, in a run with other film, I can find the best internegative and use that time for the exposure onto 4x5.


I am certain this problem has held back people from tackling the same kind of projects… hope this idea helps.

 

[Rick A]

Bill, it's been a while since I've enlarged a negative in the DR using X-ray film, my times are very fast even with the lens stopped down all the way. I'm talking fractions of a second to maybe one second depending on the negative, and that was going from a 6x6 cm negative to 11x14 inches. Contact printing times are even faster. You may be able to extrapolate it out starting with using enlarging paper at iso 3 and figure out how many stops are needed to get close, then experiment.

 

[Bill Burk]

Thanks! I’ll be adding about 3.0 ND then!

 

[Rick A]

I wish I could find my notes on my procedure for it, but I seem to have lost a box of darkroom gear during my move and the notebook was in it. I at least had the luxury of developing by inspection with x-ray film. You may want to practice with some inexpensive ortho film and dilute developer under a dark red safe light.

 

[Mick Fagan]

This sounds interesting, but I would be doing ½ stop increments at the very least and would certainly think about ¼ stop increments.

I presume you are going from 35mm B&W reversal image to a projected image on a darkroom easel onto 4x5" film. If so then your calculations may need to include the difference in projection light intensity from the film plane of the camera to the easel.

One aspect of the projection part is the enlarger height differences, that is, if you are changing the image from the whole to possibly cropped in various frames. Once you have a known successful exposure and enlarger height figure; obtaining a white light reading can be a great help.

Basically you arrive at the successful combination. Turn off the darkroom lights and take an easel reading of the light without the negative stage in the enlarger using an enlarging meter, or a normal light meter. This then becomes your standard light intensity reference for the standard transparency used for your test.

Changing enlarger height is easily corrected by this method with a stepless (if possible) enlarging lens to retain your correct light intensity.

Another way we used to keep enlarging times identical when changing the enlarger height when doing dupes, was to use all three filters as a neutral density filter. 30 units of each colour is one stop. We used the little Ilford handheld enlarging meter for this purpose, simple, fast and accurate.

The Schneider Componon S enlarging lenses with their stepless setting and click setting arrangements, combined with their side lever which allows you to not touch the aperture ring and yet have a wide open focusing setting were easily the best for this job.

Dust is your enemy for this process, big time.

 

[Mick Fagan]

Another thing, make sure you standardise on a film developing procedure that doesn't change one iota.

Slightly warmer/cooler developer, slightly imprecise developer times and/or agitation techniques can make big differences to the contrast of dupes.

We used a 320mm wide roller transport E6 machine converted to B&W, developer replenishment was critical, retaining a constant temperature wasn't an issue. Some days we had lots of 4x5" and 8x10" dupes running and replenishment was our only problem, which was a good day.

Did I mention Dust?????

 

[Bill Burk]

Yes, I'll be enlarging to (probably) a Speed Ez-El holding the film, while working to put the film plane of the camera at the same plane as the film in the easel.

I'll frame as necessary to get the entirety of the original transparency with a little clear space onto the 4x5. The height will be locked and I'll avoid using the enlarger for anything else (or at least I'll note the heights).

The camera tests will be as if I were doing test strips of a general area of interest. My original thoughts were to do third-stop sequences.

Focusing would be a bear if I go up to 3.0 ND but if I am dropping a filter under the lens it might not be too bad.

 

[Bill Burk]

I am going to develop the camera tests and the final negs to 0.62 CI.

I think since the transparencies are already 'high contrast' - as in "they look right visually as-is" I do not need the negative to be developed to "gamma infinity". I need the negative to take what looks like a natural scene to what looks like a normal negative.

So 0.62 CI should be the right aim.

 

[Mick Fagan]

Sounds good Bill.

We (I) always used DeVere enlargers, 4x5" and 810" for either duplicating or reducing/enlarging from the original. They are as solid as a rock. we had one 10"x10" Durst enlarger with a curtain shutter, this was brilliant at film dupes as the light was always on and the temperature light intensity arrangement basically never changed.

I would be thinking of possibly using the enlarging filtration for ND, with 90 units of each colour that is three stops (usually) this could be less of an enlarger shake than moving an under the lens filter in and out. Maybe............

 

[ic-racer]

I need to make some B&W prints of 35mm slides via 4x5 internegative, and like you, am not looking forward to doing test strips with 4x5 film.

What I plan to do is use my Horseman film-plane exposure meter. I'd like to put the 1.35V chip in that meter.

 

[Bill Burk]

You'll be happy when you get that chip in. With the little Yashica meter it changed characteristics from being a typical jiggly needle to a rock hard lock-on reading movement. It's pretty cool how stabilized voltages help exposure meters.

 

[ic-racer]

You'll be happy when you get that chip in. With the little Yashica meter it changed characteristics from being a typical jiggly needle to a rock hard lock-on reading movement. It's pretty cool how stabilized voltages help exposure meters.

As I'm studying the Horseman design. The high circuits are 1.35V but the low level circuit is 5.6V (PX26 Mercury) circuit. Have you come across a voltage regulator that will produce 5.6V?

 

[Doremus Scudder]

Well, I'd be mounting a macro lens in a shutter on my enlarger and making a bunch of test exposures at different shutter speeds, or you could make a cumulative-exposure test strip with successive exposures and uncovering the film a stripe each time.

Of course, you have to do this all in the dark if you use panchromatic film, but with a bit of thought, some tape and cardboard, you could make a jig.

And, you may have to do some tests for development time too (I did, anyway).

I question the use of TMY2 for your copy neg material though. In the good-old days, I used Panatomic X or PlusX. Today, I would use TMX. It's slower, finer-grained and likely has a better curve for repro work (at least for copying prints, not sure about your transparency).

Best,

Doremus

 

[Bill Burk]

Thanks Doremus,

I was thinking, this "film under enlarger" topic has been discussed from time to time but few get past the mental hurdles of "working in the dark with film". I admit even I have postponed this longer than justified, because I have a ready darkroom and tools/experience to work with film in the dark. There seems a stumbling block.

And I thought, what if I just set down whatever camera happens to be loaded with film and fire a few shots. Next time I develop that film I'll have the answers I need for the work I want to do.

I happen to have TMY2 in both formats, and considering I am enlarging from 35mm Panatomic-X the larger film format will make up for the difference in grain.

I'm not sure about the shantytown on TMY2. For that a Lith film would be preferable. But while I'm at it I might try to see what I get, it may be good enough for what I am looking for... a chance to show a historic halftone image in high fidelity.

I know what you mean that if you don't match the grain to the purpose you can have disappointment. I once went the other way, making copy negatives onto 35mm Panatomic-X from 8x10 prints that were originally 4x5 shots. Though the copy results were acceptable to everyone I made prints for, the grain of 35mm lost detail from the originals and I could tell the prints were inferior.