[QUOTE=cao] The spec sheets for the Luxeons seem to require a constant current somewhere between 750ma and 1000ma for operation. /QUOTE]

My understanding is 750 you get the stated light output and lifespan. 1000 you get more light but less life. OTOH I'm not sure the lower lifespan would really matter in an enlarger. But if you use less then 750 you'll get less light but longer life?