Quick question about aluminum flashing. As I understand it, the main point of lining the rear of the PJ is to keep that part of the box from heating up too much. But how much lining? Sides, bottom, top, back (behind the lamp)? Does the siding also reflect infrared? I could see this possibly raising the temp at the collimating fresnel and LCD.

Does the collimating fresnel correct the light angle regardless of the angle of the light coming in? I see there being a lot of "dirty" light (light hitting the fresnel at different angles) that would be attributed to more siding.

Ok...so not such a quick question afterall. Any help is appreciated!

You'll have a hard time arranging flashing in such a way that it negatively impacts other stuff by reflecting nasties. Just paint the exposed surfaces flat black - you can use hi-temp barbeque grill paint.

Flat black will also reduce "junk-light" reflections. The rear fresnel only "likes" light coming from the focal point and other stray light is just crap.

The flashing serves to protect underlying wood and other sensitive stuff like - say - wires running through the light chamber area, controller boards, etc.

You certainly can build with no flashing at all but in some cases it's pretty much a necessity. Sometimes it's just a case of one opinion over another too.