LED red/amber bulbs for safelights?

Discussion in 'Darkroom Equipment' started by imush, Jan 4, 2011.

  1. imush

    imush Member

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    I am getting together equipment for a makeshift darkroom. These days red or orange LEDs are probably better (and cheaper) than safelights.

    Anybody has current recommendations? I haven't seen recent posts about this.

    There are plenty of cheap red LED bulbs for decorative lighting, but I am not sure about the wavelength. I know OptiLED red and amber reportedly work well, but these are among the most expensive. They are also too bright, a 1W LED should be enough.
     
  2. Steve Smith

    Steve Smith Member

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    There have been a couple of threads about this recently.

    I think that generally the red LEDs are so far away from the sensitivity of the paper that they are o.k. Orange and amber may require some testing.


    Steve.
     
  3. youngrichard

    youngrichard Member

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    Maplins sell mains voltage LED lamps rated at 1.8 watts. Problem is they are on a GU10 fitting and so far as I can find you can't get a bayonet to GU10 adapter to allow easy fitting to a bayonet socket. So I bodged a couple onto old bayonet fittings (don't think you can get them now either) and put them in my 2 Kodak Beehives. Didn't have the nerve to do without the orange filters already there so I put them back in. Gives a more directional light which I have tested and found safe with max-flashed Ilford MG paper for 10 minutes on the enlarger baseboard, about 6 feet from the nearest beehive.
    Maplins used to quote a wavelength for these lamps which come in several colours but I notice in my latest catalogue, now a year old, that they no longer do, though they do for other LEDs.
    Richard
     
  4. Christopher Walrath

    Christopher Walrath Subscriber

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    I would ismply put some up and run a test on a sheet of paper to see what kind of fogging you will get. Best way to be sure.

    Sorry, in answer, I do not use LED's, just a cheap Freestyle safelight.
     
  5. imush

    imush Member

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    Yes, I was looking at the traditional safelights, but then thought that there is no longer a good reason to buy them: LEDs should be much better (if the wavelength is right), cheaper, and compact than filtered light from incandescent bulbs.
     
  6. youngrichard

    youngrichard Member

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    Sorry I didn't make clear, it was orange LEDs that I put in the beehives.
    Richard
     
  7. domaz

    domaz Member

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    Look the datasheet for Luxeon Rebel Red-Orange LEDs. They are quite far away from the sensitive range of paper and they have a nicer color closer to Amber instead of Red. I am getting some of them in soon and I will report back on there safety.
     
  8. imush

    imush Member

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  9. MattKing

    MattKing Subscriber

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    These work well as safelights in standard fixtures, using Ilford MGIV-RC, Kodak Polycontrast RC and, IIRC, Oriental RC:

    http://www.dealextreme.com/details.dx/sku.5136

    They are bright and operate without much heat. They are also very inexpensive and are shipped quickly. My only problem is that they don't pack them all that well.
     
  10. Mainecoonmaniac

    Mainecoonmaniac Subscriber

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  11. Ken Nadvornick

    Ken Nadvornick Member

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    I have been using the red version of these standard base S-11 Festival LEDs with spectacular success. Pre-fogged testing with Ilford MGIV, both FB and RC, shows no safelight-induced fogging out to at least 60 minutes.

    The only caveat is that none of the LEDs I tried emitted absolutely pure light. In addition to the main peak centering on the design wavelength (635nm in this case), the S-11s were also generating small blue and green spikes. I could see these clearly by simply observing the light reflected in a standard CD disc. These spikes did add to the paper fog levels after a few minutes exposure.

    I solved the problem by enclosing the bulbs under a single layer of Rubylith. This acted as a poor man's low-pass filter, effectively blocking the higher frequency spikes while passing almost all of the lower frequency red light.

    The blue and green disappeared from the CD, and the safe exposure times for the papers jumped to the 60+ minute mark. (I stopped the test at that point, so I don't know how much further it might have been able to go.)

    I eventually hacked up a DIY bank of six of these bulbs to create a relatively bright working environment.

    Ken
     
    Last edited by a moderator: Jan 4, 2011
  12. Kevin Kehler

    Kevin Kehler Member

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    I actually just ordered 4 of these last week (they are not here yet); have you used them with FB paper (you only list some RC papers). I would assume they would be safe (and I plan on testing them) but am looking forward to being able to see a little better in the dark.
     
  13. MattKing

    MattKing Subscriber

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    Kevin:

    I use RC almost exclusively, so no tests with FB I'm afraid. FWIW, my MGIV RC tests include the regular, warm tone and cool tone versions.
     
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  15. Steve Smith

    Steve Smith Member

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    If it works with RC it should be the same with fibre. It's the same emulsion on the surface.


    Steve.
     
  16. 23mjm

    23mjm Member

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  17. Ken Nadvornick

    Ken Nadvornick Member

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    As mentioned above, beware of the minor secondary and tertiary emission peaks in other non-red parts of the spectrum.

    When other threads have mentioned unexpected fogging from what they assumed from the manufacturer's spectral graphs to be pure LED colors, this was likely the culprit.

    Without the Rubylith addition to my red LEDs my papers were demonstrating noticeable additional fog in as little as 10 minutes or less.

    Ken
     
  18. Kevin Kehler

    Kevin Kehler Member

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    I am going to get a little off topic but is it normal for people to leave paper out for that long? I always was told to the last thing you do is take paper out, expose as soon as possible (everything should be ready to expose prior to removing paper from package) and develop immediately. Given my constant walking in and out of the darkroom for fresh air and to wash (bathroom is down the hall), I guess that length of time has never been an issue for me as all of my paper stays in its' package unless being used immediately.
     
  19. jon.oman

    jon.oman Member

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    Okay, I have a few standard (read old) 5x7 inch safelights, with the 1A red filters. Since normal replacement lightbulbs are hard to find (15watt), could I use one of the LED bulbs mentioned here? The filter should be about the same as rubylith.
     
  20. 23mjm

    23mjm Member

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    The extraneous light emissions can be said of all safety lights. As with anything a little testing can go a long way. My little 5X7 light uses a 15 watt bulb, when it goes I will get a red and amber LED light and stick in the housing without the filter and see how it works.

     
  21. Ken Nadvornick

    Ken Nadvornick Member

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    It depends on the workflow.

    I use that Aristo VCL4500 variable contrast light source. Even with brand new tubes it was never designed to be high-intensity. Base exposure times of a couple minutes are not uncommon, especially for larger prints.

    I also use a standard development time of 4-minutes in home-brewed Ansco 130 for my fiber-based paper. This can occassionally expand to 6-minutes, if the desired effect calls for it.

    Add to the above the occassional complex dodging and burning sequences - sometimes using multiple contrast grades - which I design for repeatability around multiple 3-second omissions and bursts, and the time can add up.

    Between exposing activities I do have a large black sheet of construction paper that I lay over the easel to keep safelight exposure to a minimum. But creating and developing a complex final print can sometimes take over 5-minutes to complete.

    When I tested for safelight fog I did so in 5-minute increments. Without the extra filtration I noticed additional fogging somewhere between the 5- and 10-minute steps. This was too close for comfort to my worst-case printing scenarios.

    I realize that a lot of workers prefer quick, single exposures of 10-seconds or less, followed by immediate RC development times of perhaps only 90-seconds, and not much in the way of dodging or burning. For this workflow 5-10 minutes open time is more than sufficient, if not overkill.

    I just want to make the point for those who might read this thread later that if their open times run longer like mine sometimes do, one source of unexpected fogging (highlight degradation) could be the light from those LEDs that they might have been led to believe was pure.

    It's worth noting that I was not originally looking for 60+ minutes. That is overkill in the other direction. It just turned out that a single layer of Rubylith over a 635nm LED produced an extraordinarily pure red light, and was a perfect match for the two Ilford papers. And I thought that discovery was worth mentioning.

    Ken
     
  22. imush

    imush Member

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    So there is no fog unless the paper was slightly exposed, in which case these lights would add to the fog? Why is there such a difference?
     
  23. MattKing

    MattKing Subscriber

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    Safelight fog manifests itself in two ways:

    1) visible fogging in areas of the print that otherwise show at least some tone; and
    2) degradation of highlight "sparkle" in areas that don't otherwise show any tone (think specular highlights).

    The first type is easy to see with a rudimentary test. The second type is a little harder to detect.

    One detects the second type by first fogging the paper slightly - just enough to overcome the paper's "inertia" to low level light. That fogging exposure is done in otherwise absolute darkness. Next, an opaque item (e.g. a ruler) is placed on the paper and different sections of the paper are exposed to the safelight for different times (e.g. 1 minute, 2 minutes, 4 minutes, 8 minutes, etc.). Then the paper is developed (again in absolute darkness).

    If the safelights are completely safe the developed paper will exhibit a consistent light gray tone - you won't be able to tell where the ruler was.

    If, however, the safelights are only partially safe, the sections exposed for shorter periods will be the same tone as the part hidden by the ruler, while the sections exposed for longer periods will be a darker tone than the part hidden by the ruler.

    If however, the safelights are not at all safe, none of the exposed sections will be the same tone as the part hidden by the ruler.

    Without the initial slight fogging, some or all of the subsequent safelight exposures may not be enough to make their effect obviously visible (in the test) even if they are enough to cause the degradation of highlights referred to above.

    Hope this helps.
     
  24. dpurdy

    dpurdy Member

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  25. Ken Nadvornick

    Ken Nadvornick Member

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    What Matt said...

    Paper has a certain exposure threshold which must be reached before a minimum tone will register. The danger in safelight fogging is not really a gross darkening of the paper. That's easy to recognize. Instead, it's the tendency to "use up" that pre-tone threshold with non-image forming exposure. When the intended image is then projected on top of that, the resulting highlight tone will end up developing out too dark.

    And to make things even worse, when that now too dark highlight tone is allowed to dry, the "dry down" effect will render it even darker yet. The net effect is one of an unexpectedly lower contrast, flat looking print. These are the "degraded highlights" referred to above.

    Often the source of the problem is not readily apparent. The printer will claim to have already tested for safelight fogging and found none. But if the test was not a version of that second, pre-fogged test as described by Matt, then chances are good the source of the effect will be missed.

    Ken
     
    Last edited by a moderator: Jan 4, 2011
  26. Ronald Moravec

    Ronald Moravec Member

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    Red works but is less efficient than proper amber filter, ie less usefull light to human eye b/4 fogging.

    Good news it preserves night vision better