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Survey of paper-safe red LEDs (safelights)

polyglot

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I've been using a 3-LED bike tail light for my safelight; it's enough illumination (just) and quite paper-safe. I wanted to buy a mains-powered LED bulb to get better illumination and not change batteries, so bought a couple to try. I've been testing spectrum by diffraction off a CD and my $3 bike light shows only red, maybe orange, components.

The first lamp I bought is a 1.8W, 38-LED, 220-240V E27 thing from China for $1. The branding on the box is "FLY" and three balloons; it's made by Shenlong Company Ltd. Currently listed on eBay as #290687055751.
The CD test shows it has significant spectrum into green and even blue so I haven't paper-tested it.

I'll post more as I receive more in the post; can other people please post their positive and/or negative experiences with specific LED bulbs? There are a few that have been reported as good in a bunch of other threads so I'd like to gather them here and make this a sticky. Please tell us whether you did the CD test and if you've checked for paper-safety, which paper(s) and durations and whether you did the test properly with pre-fogging.
 
I've been using a head lamp with a single red LED for years. No problems.
 
I should have thought to try ebay for LED bulbs. I've got a couple of these in use, but they were pricey relative to what you paid. They also show a bit of yellow/orange and green when looked at with a CD. So I wrapped them in rubylith and they work very well. I have tested them with paper out to 10 minutes from just a foot away when used this way and they showed no problem. I did not test them without the RubyLith. They are very bright.

I don't think any of the red LEDs are only going to be a pure red, so you may want to get a few big sheets of rubylith. The same LED viewed through rubylith shows only a red spectrum. I just taped the rubylith to the bulb with clear packing tape; not pretty, but effective.
 
What are the benefits of using LEDs over a regular old Safelight like an Ilford 902?
 
As discussed in this thread: (there was a url link here which no longer exists)

The LED in question is this one: http://www.superbrightleds.com/moreinfo/g-series-minature/2-watt-g11-globe-bulb-360-degree/440/ It may or may not be suitable for your use in Australia, however.

Anyway, I bought two of these as a result of this tread and tested them, and reported this in the above thread:

"... I re-tested my current setup with multiple 0C filters that had tested "safe" before, and it tested safe again. I then used the same procedure using the pair of new LED bulbs, and they, too tested safe.

"(I probably should have tested just one LED bulb first, but I reasoned that if the pair passed, I wouldn't need to test just one by itself. Turned out to be true.)

"I then combined the new LEDs with my current safelights and tested that, and also got a "safe" test. I was both surprised and pleased. I finally extended the test from 7 minutes (using the Kodak procedure) to 10 minutes and still got a clean, safe test!

"I use the Kodak method http://www.kodak.com/global/en/consu...Safelite.shtml. This is very similar to the Ilford procedure http://www.ilfordphoto.com/aboutus/page.asp?n=148.

"The Kodak test goes to 7 minutes. It was a simple step to add another 3 minute exposure to get a cumulative 10 minutes of safelight exposure. All of this was done with Ilford Multigrade paper.

"Disclaimers: Different papers must be tested for, and each darkroom setup, or change thereto, must be tested.

"Therefore, all this proves is that the specific LEDs mentioned by the OP work in my darkroom with Multigrade. It does not speak to all red LEDs, other types of red bulbs, strings of Christmas tree lights, etc."

Ghostman said:
What are the benefits of using LEDs over a regular old Safelight like an Ilford 902?
Click to expand...

Bottom line: (IMHO) none. But see: (there was a url link here which no longer exists)

I am not against LEDs. I believe LEDs will replace tungsten in the future. But there is certainly nothing wrong with using either light source with a proper AND TESTED filter.
 
rbeech: do you have a model number or link?

Larry: I will probably test again with rubylith as I have a bunch of it. It'd be nice though if we could find a handful of widely-available known-good models that don't need additional filtering.

I also just tested some individual bright-red LEDs; very monochromatic and safe at around 650nm. They're not a readily-usable bulb module though.

Ghostman: if the LED spectrum is paper-safe, it will remain so. There is no filter that can fade or scratch and therefore become unsafe. The idea is that bandgaps in the LEDs are finite and therefore the right LEDs should be monochromatic with lower photon energies than the activation energy of the paper emulsion. The right LEDs are inherently safe for basically infinite exposure time, whereas a filtered incandescent will always eventually fog paper, even if it takes an hour or two because the filtering is not capable of cutting out 100% of the green/blue/UV output from a filament.

David: what is the voltage rating on those? I don't see anything on the webpage; is there something marked on the bulb or its packaging?
 

Interesting. Many thanks. I'll investigate this.
 
I use a red OPTILED Festival lamp. It's got a narrow spectrum, standard Edison screw base, 35,000 hour rated life and is universal voltage. Specifications here:

I've used it with a variety of papers, including very sensitive VC types, and experienced no fogging out through six minutes exposures. Price, considering it can be simply screwed into a standard lamp socket and that one will probably last the rest of my life, seems very reasonable to me:


I bought a half dozen with the intention of placing them uniformly along a planned long, narrow, permanent darkroom in a home to be built. For now, a single one bounced off the ceiling is adequately bright in my small, temporarily converted bathroom occasional darkroom.
 
I installed this one: http://dx.com/p/e27-0-7w-7-led-25-lumen-red-light-lamp-bulb-85-265v-ac-37160 in the community darkroom that we run here and a member of the group said that she tested it and it seemd safe.

I need to do some tests myself in order to be able to recommend it without any doubts, though, because I am not sure if she did a thorough test !!

I have a couple of good darkroom safelights in my own space (Osram Duka, Ilford) but I don't know if I will be able to find a replacement for the tungsten lamps found inside once they're gone !!
 

The superbrightled.com models I've always used were deep red ones with an array of LEDs (like 16-30, can't remember) with "wide" dispersal.

Actually, I just found the 2009 invoice in email:

Quantity: 2
Product: E27-x24 LED bulb $ 7.95 (each)
Options: Red Narrow 15 Degree

Quantity: 2
Product: E27-x24 LED bulb $ 7.95 (each)
Options: Red Wide 100 degree


SUBTOTAL: 31.80
SHIPPING: 5.00 US Mail (Estimated)
TOTAL: 36.80


These have always been perfectly safe and throw out a good amount of light. I used the wide and narrow at the same time, bouncing off a highish ceiling. It looks like this thing:

Dead Link Removed

But in red. Not sure they sell it anymore.
 
Ebay 251062344308 just arrived; it's sold as a Red LED in E27 base; 85-265V 3W, absolutely no markings on the case or packaging. Has cheap-looking metallic fins up the sides of it and a hemispherical opaque white dome; I think it's meant to look a little like one of the premium very-high-power bulbs that have the fins there for heatsinking.

The surprise: it's actually an RGB LED and comes with an IR remote control that allows you to set the colour or colour-cycling/flashing modes as well as dim it! For $4 shipped. WTF.

The CD test is hard to do because the reflection of the light is pretty big, so the spectrum doesn't separate well. But it definitely reaches up into red/green territory a little.

The real failing of this bulb (for safelight use!) is that when powered up it goes into colour-cycle mode at full brightness and you MUST use the remote if you want it to stay on red. Construction is also horrific; you can see the PCB waving around inside the case supported only by a couple of wires.
 
I'd consider SBLED but they don't seem to sell an affordable, low-power (<5W) 240V red LED in E27 base.

Browsing through SBLED, I find this. The one I just received from eBay appears to be either that exact same bulb or a cheap clone of it. The remote is absolutely identical.
 
I have a Petzl red LED head light that I use to augment room safelights. It works well for "task" lighting, and doing things like monitoring lith prints when I leave my overhead safelights off.
It seems like the particular one I have is no longer a current model, so testing of what's available would be needed.
 
I did some safelight testing tonight with Arista paper and the 1.8W red LED that arrived first from eBay. It's OK at 16s but fails at only 32s of exposure.

I tested again with two layers of rubylith over the front of the lamp and it passes at 512s (about 8:30) with pre-flashed paper. I didn't bother testing any longer than that because a) I'm impatient and b) I never have paper out that long.

The thing is so bright that it's impossible to compose in the easel with it on, because it completely washes out the projected image. Really, incredibly bright, with perfect visibility into the darkest corners of the darkroom; probably a good 6 stops brighter than the 3-LED bike light I was using. I'm going to have to rig up a switch or something, maybe some black tape across the front to dim it by a stop or two.
 

Can you bounce it off of a ceiling or some other diffusing reflector?
 
MattKing said:
Can you bounce it off of a ceiling or some other diffusing reflector?
Click to expand...

It's already hiding behind the speaker on the top shelf pointing away from the work area. It has to bounce off at least two walls already before it can reach the paper!
 

This has been my similar experience with my (635nm) red LEDs in the past. I know you know that, but thought I'd chime in as I've been following this thread.

As mentioned several times earlier, using unfiltered LED light my pre-flashed tests failed after only a few minutes. But using a single layer of Rubylith I was able to completely eliminate the visually detectable blue and green spikes from my LEDs, then successfully test them with pre-flashed Ilford MGIV FB and RC as safe out to at least 60 minutes. I too gave up at that point.

They are not as bright as you describe. But I use six of them mounted in-line on a DIY fixture held magnetically on the top of my suspended Thomas Duplex and bounced off the above white ceiling tiles. This gives an excellent spread of soft red that does allow fine easel focusing of projected images, while allowing easy visibility of everything else in the darkroom.

And best of all, my whites stay brilliantly white. Even when using Slavich papers.

This is a valuable thread.

Ken
 

I didn't even bother to test mine without the rubylith, however I'm surprised it's so short of a time.

I really appreciate the fact that my timer turns off the safelights now that I have the red ones near the enlarger. Can you use a different relay to switch the power? The one I'm using has three wire positions, so when you close the enlarger wire it opens the safelight wire. These are very small and cheap from ebay and amazon.
 
I have had a failure of an led used as a safelight. See post #5 in this thread.

Short background: I started a thread in January about led lights and relays. (see (there was a url link here which no longer exists) ) I was considering changing out the tungsten white lights in my darkroom with leds and was asking about heat. That issue has been resolved, however, I have to admit I have never gotten around to changing the tungsten bulbs. In any event, the discussion turned to leds and relays (also resolved) and then to another thread in June (see (there was a url link here which no longer exists) ) to using leds for safelights.

The result of all this is that I ordered and installed and tested two of the leds mentioned in the original post of the June thread. (see entries #8, and then #20, where I eat a small bit of crow)

I am disappointed to report that one of the leds has failed. I do not know why, and I realize that one is not a sample. I have ordered two more since the price of two bulbs and shipping is just over $10. I will replace the failed one and have the other as a spare.

I hope that I just got a bad unit, but would be interested in any other (albeit anecdotal) experiences with any failures in led lights.

I did have the safelights switched through the enlarger timer. The prior discussion was concerned with the led possibly damaging the timer and not the other way around. I had inadvertently left the timer and safelights on for a couple of days (normally turn everything off when not using the darkroom, but I wouldn’t think that’s the cause. However, almost immediately after doing so, the bad bulb first went dim, and then out completely.

I’ve got a lot of printing to do in the near future, so the replacement bulb will get a good workout. We’ll see.
 
LED elements themselves are pretty rugged, and should not fail until about 50k+ hours of normal use. The exception is if the diode has insufficient heatsinking and is allowed to reach high (100C) temperatures. Usual behaviour is to drop to half brightness after about 60k hours and decline exponentially after that (e.g. quarter brightness at 120k hours). A cheap bulb with insufficient heatsinking will dim noticeably in much less time.

More likely is that the switching regulator built into the bulb failed. High quality regulators are quite expensive, it's the reason you can get generic $5 LED bulbs from China but a good Philips unit is still many tens of $.
 
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