I had planned to do this but have been side tracked for the moment. My thoughts:
1) Use a bunch of bulbs not one. I think T5? Home Depot had some that were pretty thin.
2) Add a shutter of some sort. I was just planning on manual timing.
3) Forget the warm bulbs. Look for at least daylight. 5500K or maybe the cool white bulbs. I think the 5500K bulbs will be more efficient then the warm bulbs. At least for VC paper.
T5 are the long ones-( I should have said T12 I think.
Okay let me try again.
The ones I was looking at were 8watts and 5500K. Plus thinner. Might want to get the ones that are 12". I had figured 12 8 watt bulbs.
Why not just have Aristo make it for you?
With that out of the way, I would stay away from LEDs. At this size, there would be so many of them, even as cheap as they may seem, it would be expensive. And their colors may not be exactly what you want, especially if you want UV or even high power violet. LED light is so locally intense that much diffusion would be required and this amounts to severe attentuation. It might be the best light source on the planet, but the risk is high. LEDs have been around a long time and trying to buy even a small one is difficult and expensive.
If you must work with LEDs, they are current devices. Their intensity is fairly linear with current. The other way to control their apparent intensity would be pulse width modulation: turning the LEDs on and off very rapidly.
For coldlights, various tubes will work. If you use a Metrolux or similar, a heater may not be required if you darkroom is not freezing all the time. You can always warm the tubes by turning them on for a bit. Beware that cold cathode tubes do increase intensity with increasing temperature and then at some temperature actually decrease their output intensity with temperature. Thus the use of a heater, but it is not perfect whereas a light integrator can make the exposure perfect.
I don't know if the newer coldlights from Aristo use a different heating system than mine, but the one I have, that isn't that old, uses a bank of resistors (the gold ones) bolted to the top of the metal chamber where the tube is. These resistors are in series with a simple thermistat that controls the temperature to about 90F.
If you don't want to use a Metrolux, then I think you'd have to have a heater controller with a fan. The temperature would have to be accurately and evenly controlled to the peak intensity output of the tube, as this is where the output is least sensitive to temperature.
Lots to think about. Good luck.
The daylight bulbs print about 1 stop faster than standard bulbs through a blue (high contrast) filter.
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