alright, i took some pics of my setup, and tried to show a little light loss test also. The lens i am using is a 135mm telephoto at f2.8. but i think i might of had it stopped down more on accident. anyway, here are the results, please excuse my super cheap digital camera i used for these pics.
Image projected onto the gg:
And Aerial image (no gg in the path):
Here are some pics of the magic tape gg:
the setup, excuse the sock, it was for balance:
front:
and another:
thank you, and hopefully someone can figure out the lightloss from the 2 pictures i provided, the aerial and the gg.
I think the way to go about measuring the light would be using a light meter with the cap on (behind the lens) for the light level of the aerial image and then cap off, reflected of the GG. This way, the measurement is not influenced by the lens used (or the maximum iris on the lens) nor by the camcorder's lens, iris or zoom position.