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Modding Ideas for some backlighting?

Discussion in 'Modding' started by bAnTAi, 17 Mar 2004.

  1. bAnTAi

    bAnTAi What's a Dremel?

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    I recently got given a framed montage of filmcells. All I want is the right sort of light to backlight it, so they show when i turn it on. I know loads of people have investigated and used loads of lighting in projects...so can anyone think of what it is I need? The closest I could come up with is a cathode, but i dont think that would give off a strong enough, wide enough light, as the filmcells are round the edge of an A3 frame.....
     
  2. ZapWizard

    ZapWizard Enter the Mod Matrix

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    A set of white cold cathodes should light it very well.
    Use a white background or defuser to spread the light.
    (You can get white plastic defusers at home depot, they are made for ceiling lights)

    Also if these are worth money, then you may also want to get a UV Filter to make sure they don't fade over time.
    (Both on the front glass, and between the cathodes and the film pieces.

    Or you can use White LEDs, it will take a tons of LEDs, and a defuser to get even light, but the overall look is better.
     
  3. kt3946

    kt3946 What's a Dremel?

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    Considering that these are works of art, you may also want to pay attention to 'color temperature'. Most filmcells use a backlight with a temperature in the 4450-5500k range, with 5500k being used for 16mm film that is to be displayed for Television.

    Most mfgs of CCFL's and LED's can provide specifications on what the 'average' color temp is of the light, which should allow you to judge what is 'close enough'. That way, the colors of the image will be shown just as the original artist intended.

    Color that is too 'cool' (>5500k) or too 'warm' (<4400k) will alter the format of the colors and possibly ruin part of the artistic impression.

    Most CCFLs tend to be in the 'cool' spectrum, which makes things look 'bluer' than they should, and washing out any reds. Incandesents (like a light bulb) are 'warmer' and provide eye-popping reds, but little blue. You should find a color around 5000k which should be just about perfect for the film. This would be either a 'warmer' CCFL, or most of the White LED's.

    BTW, you don't necessarily need LOTS of the LEDS, as there are some expanded HIGH-BRIGHTNESS leds like the Luxeon Star LEDS which provide as much if not more light than a CCFL. However, since these are point sources, you would need a diffuser to expand the light (like Zap stated).
     
  4. bAnTAi

    bAnTAi What's a Dremel?

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    right thanks, so presumably what I need is a flourescent tube, because isnt that what they use in the negative lightboxes? I did have another thought - would something like a kid's nightlight work? One of those things you plug into the wall and it illuminates gently...would it work?
     
  5. tk421

    tk421 Idiot.

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    how about a 5mm thick sheet of frosted clear/white plexi/lexan with 3mm white led's sunk into the edges?
     
  6. kt3946

    kt3946 What's a Dremel?

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    Well, the floursecent <sic> tubes used in lightboxes are actually a special type of tube, generally to give off a certain spectrum of light. This is to achieve the correct temp, and allow you to view the slides with the correct colors.

    If you can scavange one of these tubes, than that would probably work fine, however, they tend to be expensive if purchased outright. In addition, standard flourescent <sic> tubes actually tend to give off some heat due to the arcing that occurs inside the tube (hence the Cold Cathode of a CCFL). CCFLs tend to be smaller, and provide more light also.

    A 'nightlight' type device would probably not put off enough light, or do so at too warm a color temperature to show the colors correctly, as they use incandescent filiments which are very deep in the 'warm' category (generally about 2800-3200k). I wouldn't recommend an incandescent setup, unless you can get a color corrected bulb for it.

    The other thing you want to be sure of is managing heat and humidity for these film cells too.

    I would say in order of importance:

    #1. Heat/Humidity/UV light - these will literally destroy those film cells. The UV kills the color pigments in the ink, while the heat and humidity will cause the celluloid (polymer nowadays) material to warp, seperate, or crack.

    This can easily be countered by putting the cells between two plates of glass which has a UV coating on the glass. Then just make sure your humidity doesn't go below 40 percent or above 60 percent, and you should be okay.

    Also, don't put the cells over a heating vent or anything like that, as that will destroy them also. Make sure what ever lighting you use doesn't ADD to the heat - IOW, try not to use incandescents/halogens or other type of heat producing lighting. Things like CCFL, LEDs, or Electrolumenecents are better.

    #2. Color Temp - the point is to get *close*... it doesn't need to be perfect, as the eye is fairly forgiving. However, the better the aim, the tighter the target. Most CCFL providers of 'White' CCFLs will provide you with a color temp, and ALL White LED mfgs will provide one, as they are important to their usage.

    I would say my choice would be to find a pair of nice CCFLs, or if unavailable, use a Luxeon Star or set of superbright LEDs instead. :thumb:
     
  7. kt3946

    kt3946 What's a Dremel?

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    This *could* work, given the size, but you'd have a problem with dispersion in the center area. Given the A3 frame size, you'd need an AWFUL lot of LEDs around the edge to get an even lighting effect using only the edges, and given the brightness of the LEDs, you *still* might need some to fill out the middle.

    His lighting conditions also depend on the ambient lighting he is going to be viewing these in also. If he's showing these off in a bright sunlit room, it's possible that the LEDs won't be enough to display the work.

    However, if it's a nice darkened studio on the other hand, it might be sufficient. He's going to have to make that decision himself.
     
  8. bAnTAi

    bAnTAi What's a Dremel?

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    ok thanks guys, I guess I'll go with a couple of white cold cathodes and some UV film :thumb:
     
  9. Jivecat

    Jivecat What's a Dremel?

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    What about white EL sheet behind the filmcell?
     
  10. kt3946

    kt3946 What's a Dremel?

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    That could work well, but I am unaware of any WHITE color EL sheets. Do you know of somewhere that has them? :eyebrow:
     
  11. Jivecat

    Jivecat What's a Dremel?

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    BeingSeen (http://www.beingseen.com/) has a selection of EL sheets in different colors including WHITE. However, their prices seem way over the top. But at least you now know it exists and have somewhat of a starting point! :thumb:
     

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