some questions about how to calculate...

[hami]

Hi!

I have some questions you may be able to help, I hope.

1. How to calculate gain of a projection screen using measured luminance and illuminance?

2. How to compare luminance and illuminance of projection screens (rear and front projection)

Do you have an answer? I would be very happy if anybody could send any useful fiormulas or post an answer.

greetings!

[brain]

does this help?

http://www.projectorcentral.com/projection_calc.cfm

[hami]

thank you,

but it doesn?t help because I don?t want to work with an existing tool but with some formulas to calculate all needed informations on my own.

greetings!

[vjking]

Try here: Da-Lite Education (http://www.da-lite.com/educational_materials/angles.php?action=details&issueid=27)

The article is excellent. It explains the math, in detail. But if you want to make your own measurements, that will be quite tricky unless you can set up a very controlled environment, and have a very accurate light meter.

[hami]

thank you.

now my first question is answered. I already made my own measurements but I?m not sure whether I did it right. And that?s what I want to calculate. Whether my results makle sense or not.

greetings,

hami