Imperial fields accept 11'3", 11-3, 11.25, 135in; metric accepts 3.4m, 340cm. Use the viewing area, not the outer frame.

Keeping to one projector family stops the finder suggesting lenses that don’t fit. It doesn’t replace the exact projector manual or the maker’s own calculator.

Distance is measured from the screen surface to the point on the lens the maker measures from. For short-throw or mirrored lenses, the back-of-projector mark isn’t shown; use the maker’s drawing.

Output efficiency covers calibration, lens transmission, geometry and operating mode. Stack efficiency applies only when quantity is above one.

Measure the throw distance and the picture width on site. That gives the real throw ratio and tells the crew exactly how far to move the projector.

The lens finder matches real lens ranges against your placement zone, then ranks the lenses with the most room to adjust, not just the first one that fits.