Lens Calculator Lite is a tool for A/V professionals by A/V professionals.
Quickly estimate what lens to use in projectors. Just use the sliders to set the screens width and the projectors distance.
Get Pro version:
-Quickly estimate wich lens to use in projectors.
-The distance where to place the projector.
-Calculate how big screen you could use with a given lens.
-4:3 projection with 16:9 projector switch.
http://itunes.apple.com/se/app/lens-calculator-pro/id348792034?mt=8