Making an LED safelight

mehguy · Jul 19, 2016

I am looking into making a little LED safe light. Saves space. Now, I was looking at the safelight datasheet at ilford's site and the wavelength for the recommended safelights for darkroom printing. Now, I noticed that they start to drop off at around 600nm. If I get LED's that are rated for higher than that and solder a few of them in series and power them via a AA battery pack, will it be safe to use?

bdial · Jul 19, 2016

I have a strip of RGB LEDs that I operate on just the red channel for safe-lighting which work well. With the remote control power supply you can vary the intensity.
Mine are similar to these sold by Lee Valley; http://www.leevalley.com/en/hardware/page.aspx?cat=3,43629,70322&p=70326

I use these channels to mount them which makes for a nice finished look;
http://www.leevalley.com/en/Hardware/page.aspx?p=71702&cat=3,43349&ap=1

No matter what you pick, however, you'll need to test them, but I've had good luck with various red led lights, little battery powered head lights and these strips.

mehguy · Jul 19, 2016

bdial said:
I have a strip of RGB LEDs that I operate on just the red channel for safe-lighting which work well. With the remote control power supply you can vary the intensity.
Mine are similar to these sold by Lee Valley; http://www.leevalley.com/en/hardware/page.aspx?cat=3,43629,70322&p=70326

I use these channels to mount them which makes for a nice finished look;
http://www.leevalley.com/en/Hardware/page.aspx?p=71702&cat=3,43349&ap=1

No matter what you pick, however, you'll need to test them, but I've had good luck with various red led lights, little battery powered head lights and these strips.

How do I test a safe light?

NedL · Jul 19, 2016

Kodak safelight test

Some LEDs have emission lines in the unsafe range... there are posts here at APUG about using a CD as a makeshift specrometer to check.

These have worked well for me.

RauschenOderKorn · Jul 20, 2016

Most probably yes, but you should test.

I am using a commercial red LED bulb (1,5 W) in an Ilford SL-1 with the orange filter. Has worked like a charm, it is bright enough to read a newspaper in the darkroom and the light has passed all safelight tests.

bdial · Jul 20, 2016

The procedure is detailed in here in probably multiple threads. But the basic method is start in total darkness and give the paper a slight exposure under the enlarger, then place a few objects on the paper, coins for example, turn on your safe light then remove coins in intervals of 30 seconds, 1, 2 and 4 minutes. You should number where each coin is, the first one off will have the longest safelight exposure, and the last one the least. Sharpie markers work well for marking.Process the paper in the dark, and dry.
The first visible circle tells you how long it takes the safe lights to fog your paper.
The short white exposure is important, because you need to get the paper over it's "inertia" point. Ideally there should be no visible circles in that 4 minutes, and testing for longer times would be a good idea too, I generally test to at least 10 minutes.
Papers vary in their sensitivity to safe lights, so to be thorough, you need to test all your different papers if you use more than one brand or type.

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mehguy · Jul 20, 2016

Also some confusion about safe lights. Why does ilford recommend an amber light instead of a red light for its multigrade paper? Isn't red safelight's wavelength higher than an amber light?

darkroommike · Jul 20, 2016

mehguy said:
Also some confusion about safe lights. Why does ilford recommend an amber light instead of a red light for its multigrade paper? Isn't red safelight's wavelength higher than an amber light?

There is a yellowish greenish brownish (don't feel like looking up the frequency right now) sensitivity gap with most VC papers and that is also a frequency that the human eye is very sensitive to, so it is perceptually much brighter than a red safelight putting out the same amount of light. That color is the Kodak OC and Ilford 902/SL-1. I've not tested them side by side but Ilford state the 902 is brighter than a Kodak OC and just as safe. The SL1 cuts out everything below 600nm and the 902 at about 575nm. http://www.ilfordphoto.com/Webfiles/2011427111757603.pdf . It looks like the Kodak OC cuts out a lot more light http://www.kodak.com/global/en/professional/support/techPubs/ti0845/ti0845.pdf

gone · Jul 20, 2016

Bicycle taillight. If need be, put a Ruby red piece of lith over it if it's too bright, or not exactly the right wavelength light. $3 for the light, about the same for the lith, and put as many as you need for your setup. I'm used to working in very low light because all the important stuff is done w/ the lights on, so one light works fine at my place.

M Carter · Jul 20, 2016

Guys... screw all the DIY and soldering guns and sheets of ruby lith and lighting gels. Go easy on yourself. Get a couple clamp lights and a few of these bulbs and your darkroom can seem like near-daylight. These have become very popular with many APUGers, their spectral output doesn't overlap photo paper. Dirt cheap and one of the best finds out there.

Ko.Fe. · Jul 20, 2016

M Carter said:
Guys... screw all the DIY and soldering guns and sheets of ruby lith and lighting gels. Go easy on yourself. Get a couple clamp lights and a few of these bulbs and your darkroom can seem like near-daylight. These have become very popular with many APUGers, their spectral output doesn't overlap photo paper. Dirt cheap and one of the best finds out there.

Not completely dirt cheap enough for some of us in Canada, they want 20USD minimum for shipping if four of them.

Is it red or amber one, which works? Looks like red one...

spijker · Jul 20, 2016

I use the amber one. Just one of those bulbs is enough for my small darkroom. Works for me with Ilford and Adox paper.

Ko.Fe. · Jul 20, 2016

Good! I don't like red.
So, I run calculation for this "dirt cheap" bulbs. Four of them will costs 46CAD before taxes... More than half of it is shipping cost from USA.

mehguy · Jul 20, 2016

Ko.Fe. said:
Good! I don't like red.
So, I run calculation for this "dirt cheap" bulbs. Four of them will costs 46CAD before taxes... More than half of it is shipping cost from USA.

A fellow canadian knows the pain of shipping from the US.

bdial · Jul 20, 2016

That's one reason I suggested Lee Valley.

CMoore · Jul 20, 2016

Ko.Fe. said:
Good! I don't like red.
So, I run calculation for this "dirt cheap" bulbs. Four of them will costs 46CAD before taxes... More than half of it is shipping cost from USA.

Is that a lot of money for a light with a reported life span of 30,000 hours.?
I guess it is if there is a cheaper Canadian Alternative...is there one.....what is the cost of those LED Strips.?
Would it be any cheaper for me to ship these lights to our Canadian Members.?

Ko.Fe. · Jul 20, 2016

Hard to tell, USPS rates are unpredictable.
And 30000 hours is myth.
In Cabada the only cheap alternative we seems to have is bike light from dollar store and duct tape. Google Red Green Show.

NedL · Jul 20, 2016

Ko.Fe. said:
Good! I don't like red.

Be careful! The amber would probably be fine with Ilford VC papers, but it will probably fog Foma ( and Arista.edu ) VC papers.
I use the red one, it's a deep dark red and works well with all my papers. ( Foma, Adorama, Ilford, several old Kodak papers, and the new Adox contact printing paper are the one's I've used.)

darkroommike · Jul 21, 2016

It's curious, what today is considered a lot of money for a very bright safelight, e.g. LED lamps, used to be considered dirt cheap, and that's back in the 70's when the dollar had much more buying power and there were dozens of companies selling safelights for top dollar. In 1970 a Thomas safelight, new, was well over $250.00USD, today you can a smaller, cheaper, cooler running, longer lasting safelight, with no warm up period for a fifth of that. Of course you could buy Tri-X for $30 per 100 feet, too. Now it's $130 per roll on sale!

spijker · Jul 21, 2016

I agree with Mike, it's not that expensive. Hobbies cost money. But if one wants to save on shipping, have it shipped to a convenient location within the US, a UPS store near the border, where you can easily pick it up yourself. Or a US motel/hotel while you're on a trip there. Or team up with a few APUGers in your area, order more bulbs and share the shipping cost. Makes a nice excuse to get together for a bulb and a beer.

With respect to the spectral sensitivity of the various papers, APUG member Stormpetrel looked this and posted his findings in this (there was a url link here which no longer exists) (the flickr links).

Rich Ullsmith · Jul 21, 2016

M Carter said:
Guys... screw all the DIY and soldering guns and sheets of ruby lith and lighting gels. Go easy on yourself. Get a couple clamp lights and a few of these bulbs and your darkroom can seem like near-daylight. These have become very popular with many APUGers, their spectral output doesn't overlap photo paper. Dirt cheap and one of the best finds out there.

That bulb will fog paper if the process is long, as with lith. I got fog at 15 minutes. I still use it, but only for regular bw process. And I bounce it off the ceiling. I built a lamp with 36x 640nm component LED's, and this too fogged at about 15 minutes. The only perfect bulb I found was culled from a defunct dental xray processing room. Not very bright, but no fog risk whatsoever. Dental offices (particularly orthodontics) are good places to look for chemistry, film and bulbs. The digital transition is pretty much complete, but there is some stuff still out there.

M Carter · Jul 21, 2016

Rich Ullsmith said:
That bulb will fog paper if the process is long, as with lith. I got fog at 15 minutes. I still use it, but only for regular bw process. And I bounce it off the ceiling. I built a lamp with 36x 640nm component LED's, and this too fogged at about 15 minutes. The only perfect bulb I found was culled from a defunct dental xray processing room. Not very bright, but no fog risk whatsoever. Dental offices (particularly orthodontics) are good places to look for chemistry, film and bulbs. The digital transition is pretty much complete, but there is some stuff still out there.

Rich, that's interesting - I'm getting no fog with even 40 minutes of lith developing. I have one over the tray that I bounce off the ceiling, but point it down as I near completion. I also use an LED penlight with rubylith glued to the lens with black silicone. Also use them for coating canvas with Foma emulsion, 2 coats, and I angle the light very close to watch for bubbles and stray brush hairs. I haven't done a "formal" test, but I get pure white borders with lith. I overlaid the bulb's spectrum with an ilford paper spectrum in Photoshop and looked like plenty of safe area (of course, is their spectrum honest and is their manufacturing totally uniform)? I guess with long lith sessions any safelight gets dicey, but no trouble for me yet (and bright safelights are nice for lith and half-hour plus development, makes it easier to pee in the sink!)

mehguy · Jul 21, 2016

Where can I even find rubylith?

DWThomas · Jul 21, 2016

mehguy said:
Where can I even find rubylith?

Arts supply stores -- in the US Blick's carry it; made by Ulano.

MattKing · Jul 21, 2016

Here is one Canadian source, who may be able to direct you to a source for retail quantities: http://www.stanleyssigns.com/RubylithPositiveFilm

And there is some on eBay that will ship to Canada at moderate cost: http://www.ebay.ca/sch/Printing-Gra...id=2&_localstpos=V4K 2Z9&_stpos=V4K 2Z9&gbr=1

Making an LED safelight

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