Open Source Paper Flasher

[ParkerSmithPhoto]

During a printing session with a particularly difficult negative (backlit, thin shadows), and after trying dodging and burning, split grading, etc. I decided to try flashing. This was a technique I had heard about for years but had never used.

After a little thought, I found an old safelight, took out the filter and replaced it with two pieces of foam core. I screwed it to the ceiling, ran an extension cord down to the Darkroom Automation f-stop timer and set to testing.



With a standard 15 watt bulb, I was surprised to find that it took 3 stops (~8 seconds) of exposure to get me below the threshold, and a full 3.5 stops (~12 seconds) to produce just the very lightest gray below the paper base on Ilford MGFB. That seemed much longer than I ever would have imagined given how bright it seemed when switched on; I will no longer worry about the tiny bits of light that periodically creep around the door on bright days.

Anyhow, it works! Within another 20 minutes, I had my pilot 8x10 tests for the eventual 16x20 print, which will probably get done tomorrow. After wrapping up, I dug out an old Time-O-Lite which I will use so I don't have to plug and unplug from the f-stop timer. The main thing is just the modified safe light. You could probably put a small nylon strap on it and temporarily fasten it to an enlarger column or head if you wanted to do local flashing/burning. It's stupid easy, cheap, and it works.



I'm releasing this under the GNU Public License, which means that if you take this idea and do anything GNU to it, you have to send me some $$$. Hope that helps!

 

[glbeas]

I did something similar with a cheapo desk lamp hung on the wall next to the enlarger with a dimmer and a spare time o lite. Works pretty easy, I can flash the paper as I'm getting it ready to go in the easel.

 

[SkipA]

Why not just pre-flash using your enlarger light source? Raise the head up the column all the way, set the smallest aperture on your lens, place some coins on your test strip, and expose it in 1/2 second increments? Develop, choose the level that just barely shows the slightest hint of color. Very easy. Works.

 

[Trond]

Good idea! I have a spare timer I can use, and a spare safelight somewhere. I think will set up something similar.

Trond

 

[ParkerSmithPhoto]

Why not just pre-flash using your enlarger light source? Raise the head up the column all the way, set the smallest aperture on your lens, place some coins on your test strip, and expose it in 1/2 second increments? Develop, choose the level that just barely shows the slightest hint of color. Very easy. Works.

Then you'd have to move your perfectly focused and positioned negative. Sounds like a lot more work to me. And a much greater chance of expensive mistakes, too.

 

[David Allen]

I have a piece of opaque plexiglass mounted where the red filter under the lens was. I set up, focus and do my tests and, should on the rare occasion I need to do a pre-flash, I simply swing this in to the light path and do my tests. Works great, no need to build anything, no need to change enlarger position or settings. It also enables me to accurately pre-flash only a portion of the paper if necessary.

Best,

David
www.dsallen.de

 

[SkipA]

Then you'd have to move your perfectly focused and positioned negative. Sounds like a lot more work to me. And a much greater chance of expensive mistakes, too.

If I'm working with negatives that need pre-flashed paper, I just pre-flash 10 or 20 (or whatever) at a time and put them in my paper safe ahead of time. You really need to have the paper completely dry to evaluate the amount of pre-flash you need, so it is easier to do that before your printing session rather than repeating it for each negative.