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Ulophot
18-Jun-2017, 08:31
As I continue hopeful preparations for getting back to photography -- film, B&W only -- and my darkroom, the potential for masking 4x5 negs in the enlarger for better dodging/burning control when needed is something I'd like to explore when I get there. I don't mean a pin-registered system, only the use of marking on and/or cutting out of vellum aligned on a diffuser above the neg.
My enlarger is a D2 with a Zone VI cold-light head in the original D2 collar made for condenser lenses. I bought a piece of 1/8-inch milk plexi years ago but never used it. It's a bit narrower than the diameter of the head though longer on the other dimension. My questions for any who have used a similar set up, are these:

1. Some photographers have written of having the neg carrier top piece opening machined slightly so that a somewhat larger piece of plexi can sit in it (velum taped on top), allowing perfect alignment/replacement each time. My carrier top piece is only 2 mm thick. Perhaps the machining would be just a millimeter?

2. The additional problem in this case would be that the cold-light's diffuser sits directly inside the aluminum head collar, which would not allow sufficient clearance for the carrier plexi's thickness. Omega used to have a cardboard spacer to hold the bottom condenser lens up about 3/16 of an inch, perhaps to kept bottom surface dust further out of focus. That would conceivably solve this problem. Anyone with such experience, or who can suggest a material for this operation to someone who is not skilled (gross understatement) in creating such things?

3. A third possibility is getting a piece of plexi wider than the present one to avoid direct light spill from the head, but then the issue of light spill still exists as it diffuses out the edges and around the top of the plexi. Edges and top around the collar circumference could all be painted black, I suppose. Comments?

Thank you.

LabRat
18-Jun-2017, 09:57
Well, the easier way would be to use a glass neg carrier, and the masking could be taped on top, or the top glass could be replaced with another diffuser...

But for B/W, if you are having a contrast problem, look to using a compensating developer, higher dev dilutions, exposure calibration, multigrade papers etc, as you should be able to expose film well enough to hold a range that should print well with little manipulation (esp with a cold light), so cross the masking bridge IF you come to it...

Testing, testing, testing...

Steve K

ic-racer
18-Jun-2017, 14:41
Or work with bigger masks suspended above the paper.

jvo
24-Jun-2017, 19:18
Or work with bigger masks suspended above the paper.

+1

i have an identical setup.