Actually I´m trying to convert my old enlarger to LED lighting because of several different reasons.
1-Enlarger bulbs are not available here since the ´80s.
I had to experiment with different bulbs and even positioning them carefully I had serious troubles to get even lighting.
2-Incandescent lamps produce too much heat which may cause neg distortion. This is specially awfull when you have to be ready for an exhibition. Paper is also expensive and I´m not eager to threw my money to the dump.
Any forced ventilation may cause vibration in the enlarger head as well as to move dust particles which may land on the condenser or worse, on the neg.
3-Low power FL and CCFL aren´t environment friendly and they require also special control techniques to get them stable in terms of lighting.
Worst of all, they aren´t made in the shape and size that will fit an old enlarger.
Then having all this in mind I started thinking of what can be done to get a low consumption stable light source. The only answer was LED lighting.
Some time ago I found a website whose owner did that and made a light source with white, amber, green and blue LEDs that was used for VC paper. Unfortunately, I didn´t recall where, supposedly my HDD will do, but it crashed…
Problems and benefits of LED lighting:
1-White LEDs have a lot of blueish light (about 5600 to 6200 K),. as well as some spurious UV emision so it has to be stopped to avoid weird results. This is due to the white LED building structure.
2-A mix of white and colour LEDs would bring good results as long as a decent colour spectrum is obtained. This requires some time spent in experiments.
3-It must be done with regular 5mm Hi Flux LEDs, instead of the High power LEDs (3 and 5 W) because light mixing will be easier to accomplish with simple 3 or 4 channels DC dimmers.
4-It can be easier to get even lighting using a "grid" of LEDs instead of a single source with a high power LED and lenses or diffusers.
5- Excess heat isn´t anymore a problem.
That´s why I would be testing LED lighting in my enlarger as soon as I have time enough. BTW, some of the minilabs offered have LED lighting… a good reason to test it, isn´t it?
Cheers
Ernesto