LED strip Lights for Darkroom Safelight

[BryanFlnt]

When setting up my darkroom I could not find any info on the use of consumer-grade LED strip lights as a safelight - and whether it was safe. So I took a leap and am sharing my results for the good of the collective.

I bought the BlissGlow LED strip party lights (with music synch effect - why NOT!):
https://a.co/d/7Ko5Z5z

Once in hand, I did the CD test to make sure that it was just a red diode making red (and not a red/blue/green combo). Thank you @Ken Nadvornick:
https://www.photrio.com/forum/threads/another-safelight-question.121641/post-1611012

It passed. I temporarily strung up the lights in the approximate location I wanted them (thank you painter tape) and did the Kodak Safelight test - twice:
https://www.kodak.com/content/products-brochures/Film/KODAK-A-Guide-to-Darkroom-Illumination-K-4.pdf

It passed. My results showed: "The paper is safe for up to 7 minutes of safelight exposure before the enlarger exposure, and up to 3 minutes of safelight exposure after the enlarger exposure. The test indicates that conditions are safe if you limit the total safelight exposure time to 3 minutes."

Note: my work is silver geliten printing using moslty RC VC paper. I did set up an outlet near the ceiling for the future if I get into other things and need to hang a more traditional safe light.

I love it! I can see with even light surrounding me.

Pros:

• Affordable
• Flexable - you can put the ligth anywhere you want it
• Adjustable - you can change the light level
• Even light - no shadow and you lean down to focus the nagative
• Low energy usage
• Self sticking tape

Cons

• One/off cumberome: through an app. That means your phone has to be on
• Not usable plugged into your timer
• Need a system to turn it off when complete darkness is needed. I have it connected to a dedicated switch so I can just switch it off.
• potential accidental use of other light colors - it is a party light after all.
• If you don't stick the tape right the first time it can fail. Need to use cable stables to make sure it does nto come down.

So like everything else in the darkroom its a little bit fiddly, but tis a great tool to bring the modern world to safelights in an affrodable way.

 

[koraks]

Nice space, very efficiently laid out! Looks convenient.

• One/off cumberome: through an app. That means your phone has to be on
• Not usable plugged into your timer
• Need a system to turn it off when complete darkness is needed. I have it connected to a dedicated switch so I can just switch it off.
• potential accidental use of other light colors - it is a party light after all.

These can be prevented by purchasing a simple red strip and a suitable power supply (e.g. wall wart) and plugging it into a switched outlet. An additional dimmer can be useful to set the intensity of the light at a compromise level that allows convenient work while extending the time before the paper responds to the maximum achievable.

it was just a red diode making red (and not a red/blue/green combo).

It's not so much that red is ever made from a 'red/blue/green combo' diode, if that's what you meant. The problem is that there are secondary emissions from the single semiconductor diode junction in different areas of the spectrum. I imagine this is due to trace impurities in the materials used. In theory, a red LED is pure red. Practice, of course, is often a little more fickle! The CD test shows it to some extent, but in my experience it's not 100% reliable.

I find that additional filtering with rubylith can help in further extending the 'safe time' as it's really good at cutting out smaller wavelengths. The applicability of this of course depends on how you mount/install the strips.

 

[john_s]

If you look at the specs of red LEDs, you will see a distribution graph of wavelengths around a peak wavelength. The intensity scale is arithmetic, and that is misleading for us photographers who are used to logarithmic units (i.e. density). THis makes the spread to shorter wavelengths worse than it looks.
My third attempt to make a really really safe very red safelight involved dozens of very red LEDs, very bright, and very safe. That reminds me, I need to test for the Herschel effect that I hadn't heard of until a recent post

Making Your Safelight Safer

Maybe I'm paranoid about safelight safety, but in my round Kodak safelight, I installed a red LED bulb of about 30 watt tungsten-equivalent, and replaced the OC filter with a Rosco #27 "medium red" filter (bought at B&H) that I cut into a circle with scissors. It passed the following...

www.photrio.com