Can anyone tell me if using the zoom function will decrease the brightness of an image thrown from this (or any unit)? I've read that it shouldnt cause the image quality to degrade, but I wasnt sure on brightness.

I also can't recall if the zoom, shrinks or expands the image...

Forgive me as I'm still a bit new to all this, though better after several days of reading through this awesome forum.

Maximum zoom (meaning shortest throw distance) gives you maximum brightness but a bit less on/off contrast. Minmum zoom cuts brightness a bit and gives you the maximum on/off contrast.

The zoom does both expand and shrink. You rock it back and forth and it goes from larger to smaller. It basically allows you to changes your throw distance a bit for your intended screensize.