how can gain be measured?

[versurv]

I'm very impressed how much a cheap retro reflective sheet affected my pico projector brightness when I put it right next to my head.

Yes, I know the brightness drops quickly as angle and position of my eyes moves away from the projector but still would like to measure just how bright it is at the other extreme. It seems 3x bright at least. In theatres it doesn't appear to have sich a dramatic effect, but when you get your eyes right next to the projector optics it gets insanely bright.

I have a lux meter, if that can be used.

[Joe Fernand]

Gain, Peak Gain, HGA...

 

http://strongmdi.com/blog/gain-tables-what-they-mean-and-how-to-read-them/

 

To take accurate measurements you would require a 'spot meter' - not an incidental meter!

 

http://www.spectracine.com/product_3.html

 

Joe