New exposure unit idea

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From: Bill Collins (photo@intrex.net)
Date: 02/05/01-08:22:30 AM Z


Quite a while back, someone reported fogging of Pt prints due to the use of studio strobe lighting in the same room, and wondered if a flash could be used as a light source for alt printing. If anyone tried it, either they didn't tell the list, or I missed the posting.

I tried it over the weekend and it works! Here's what I did:

Light source: White Lightning 1800 monolight WITHOUT the UV blocking tubes
Paper/process: commercial "sunprint" Cyanotype paper

First, I put a sheet of the paper on a table, with coins on top of it and gave it one pop with the strobe. The flash reflector was almost touching the paper. This resulted in a print with the exposed areas about as dark as the paper can produce.

Next, I put another sheet of paper and a 4x5 negative (HP5, ISO 200, normal development) in a spring back contact print frame. I backed the flash off to about 1 inch from the front of the frame and exposed with 5 pops of the flash. The result was a slightly overexposed print.

I tried another, denser, negative and it printed fine with 10 pops.

I will try an 8x10 when I get a chance. I expect it to take about 4x the exposure.

My limited experience with the sunprint paper is that it requires roughly the same exposure as a Pt/Pd print, so maybe the flash will work for that process too.

BTW: the flash recycles in about 3 seconds, so my prints had an exposure time of 15-30 seconds.

Bill


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