Is green LED safelight?

gma · May 10, 2005

Tonight I loaded a 35mm roll of J&C Classic 400 onto the reel in my darkroom. When I was almost finished loading I noticed the glow of the green LED on my electrical power strip. The light was under my counter and less than two feet from the end of the film which was dangling near the floor. I expected that the film was ruined, but developed and discovered that the negatives are normal with not a hint of fogging. I will cover the LED with some black electrical tape next time.

I do not recommend using green LED for a safelight, but I was lucky this time.

josephaustin · May 10, 2005

The glow in the dark timers, my Gralab and timeolite do not fog my film, I use the gralab to time my sheetfilm developing in open trays. Similar shade of light I assume would also not fog film.

Loose Gravel · May 10, 2005

Green is not safe; the low intensity was below threshold.

colivet · May 10, 2005

Led's light spectrum is really, really narrow. It can still expose film if you wanted to.

I use those little led safety night lights to inspect film development progress. It never exposes the film, which is of course quite desensitized during development.

127 · May 11, 2005

the trick with green is that our eyes are very sensitive to it, while panchromatic film is (roughly) equaly sensitive to all frequencies.

For that reason green is a better safelight than red for panchromatic material - what looks bright to us is still pretty dark to the film.

By comparason a blue light which we would hardly notice might totally fog a film, as film is more sensitive to blue light than our eyes are.

Ian

gma · May 11, 2005

Thanks for the explantions. I knew that panchromatic film can be examined briefly under a weak green safelight during development at some distance, but I am surprised that the seemingly bright green LED very near the film did no damage. The J&C Classic films have greater sensitivity to red than most pan films. Maybe green sensitivity is less than most?

Gerald Koch · May 11, 2005

Not only is the human eye most sensitive to green light but most films have their lowest spectral sensitivity in the green region. A fortuitous combination.

The human eye is far more sensitive to light than even the fastest film. I have loaded film onto reels in what I thought was total darkness only to find that I was beginning to see the reels near the end of my task. These negatives showed no sign of fogging. Not something I recommend but no harm in this case.

steve · May 11, 2005

When I was a freshman at Rochester Institute of Technology, we were taken on a tour of Kodak to see both film and paper being made. The took us into one of the film coating facilities and into the coating area itself. The work area was illuminated with extremely dim green safelights. As stated in several previous posts, the eye is most sensitive to green which is exactly why green was chosen as the safelight color in the coating facility.

Ole · May 11, 2005

It's amazing how much light you can have in a darkroom without fogging film!

Eyes adapt to low light, film does not.

photobackpacker · May 11, 2005

The film need not show signs of fogging to be changed by low-level light exposure. Even if the exposure does not break the threshold level needed to cause fogging, it will likely be more sensitive to exposure and may well be a bit flatter in contrast.

Is green LED safelight?

gma

josephaustin

Loose Gravel

colivet

127

gma

Gerald Koch

steve

Ole

Moderator

photobackpacker

Advertiser

Is green LED safelight?

Moderator

Advertiser

Privacy & Transparency

Privacy & Transparency