Also, the beam seems to be very "hot" in the center. It would be nice if the brightness were more balanced across the disc of illumination. Probably not too much you can do about this due to the LED components available from component manufacturers.
Hmm, I suppose plastic fresnel lenses could do the job, clipped into the gobo/gel frame.
Thin plastic fresnels have been commonly used in overhead projectors for the past 40 years, though I'll have to see if I can find custom powers of them.
A more extreme and permanent solution would be for me to slightly reshape the optical faces of each of the LEDs by hand, with a custom shaped spinning polishing tool. I do suspect that this just might POSSIBLY void the warranty however.. ;-)
- Dale