How to distinguish long throw, medium long throw, short throw and ultra-short throw projectors？

1. Long throw: The projection distance of the projector is more than 1.9M, and the projection ratio is between 1.5-1.9
2. medium long throw: the projection distance of the projector is between 1.9-1.3M, and the projection ratio is between 1.5-1.9
3. Short throw: the projection distance of the projector is more than 1.3M, and the projection ratio is <1
4. Ultra short throw: The projection distance of the projector is more than 0.5M, and the projection ratio is less than 0.4

Except for the ultra short throw projector, others are called ordinary projectors

How about projecting a UST ALR screen with a normal projector?
Since the UAT ALR screen is an ultra-short-throw projector with a special structure of two layers,


If an ordinary projector is used to illuminate directly in front of the screen, the screen cannot completely absorb the reflected light, and there will be rainbow-like stripes. and the screen will be darker



Therefore, if you use an ordinary projector, you need to choose a suitable screen according to the lumens of the projector. Except UST ALR of course!