Adding a reflector seems to increase the light output a lot! When the light output becomes too much (i.e the blacks become grey) is there a way to adjust the brightness? E.g. Would a variable resistor work with a Metal Halide bulb?

Nope, can't dim these lamps.

Brain, I think Jones Rush asked this before, but does descreasing the brightness/contrast make the panel less transmissive?

Brightness only controlled the backlight intensity and has no effect on the projection. Lowering contrast just lowers contrast. The only thing you can do is adjust the individual colors to a lower output.

Ah...of course. I didn't realise the brightness controls the backlight, makes sense.

You can get an electronic ballast, but they are very pricey, and many of them flicker just enough to annoy you. BUT, the IceCap model is able to dim a 400 watt down to 250 watts, AND says it doesn't flicker.

You can find one here: http://www.diylabs.org/projector/parts_main.htm

The cost is about $180 shipped I believe.

Second bit of help. If you don't mind a little work, cut some grooves in your projector, before the LCD, and have a piece of glass cut to size that will simply slide into that groove and allow the lid to close.

Then take that glass to a professional tint shop and have them put a very light grey tint on it. I am confident the film can handle the heat if you put it after the tempered glass, and somewhat confident it can handle it before the tempered glass. Tell them what you're doing, so they can choose between car film and house film, whichever handles the highest heat.