I used a very bright portable spotlight for the light source. It's actually got a high intensity discharge lamp in it. And that probably explains the somewhat odd spectrum. I had thought to use a slide projector, but when this thing worked OK, I just stuck with it. I set the prism on a piece of white foam-core and adjusted the angle and height to get the light beam to hit the prism the way I wanted. Then I used a couple of boxes to block the light on the left and the right, limiting the beam's width. Sort of a cardboard collimator, I guess :)
Then I just set the exposure based on metering for just the bright spectrum area and that makes the greatest part of the shot come out black even though it was all white foam core. I also moved the black point up quite far when processing the RAW in DPP.
I really should try it again with the slide projector. The spectrum might be "smoother" from the incandescent lamp versus this HID lamp. I'd also like to see if I could get a narrower beam.
Thanks! Jim H.
Guest
07-Jan-2008 03:06
Very Nice, Jim. I like your crop :)
I am interested in knowing how you created the light source? :) Thanks.
