I have been looking out fro some white Light emmiting diodes to make myself a ring light for macro work - it is probably cheaper than a ring flash. I noticed that one supplier I looked at had a range of UV leds - I wonder if these could be use in a matrix say 20 x 20 leds (or more) to be used as an UV exposure source when exposing alt process negatives.
A supplier info page is here: (no recomendations) http://www.lsdiodes.com/shop/index.php?main_page=product_info&products_id=15
I am not sure about brightness it quotes in MCD'S that I havn't heard of before.
numnutz, mcd is indeed milli-candela. FYI, This is a unit of luminous intesity, which means it is referenced to what the human eye sees and not what sensors or photographic materials see. The human eye doesn't see well at blue or violet. So something that is dim to the eye, can be bright to a piece of film or paper.