How to use a stage projector?

[SantiagoManager]

I am using a projector on stage, I only want to project onto the screen above the actors, so I don't want any of the light from the projector projecting underneath the screen (which is not fully down) How do I only project onto the area that i want to project on and have no light on the rest

[SantiagoManager]

Placement, angle & image size are the factors that control what you seek. Consider rear projection if possible.

[SantiagoManager]

Consider rear projection if possible.

[SantiagoManager]

Some factors as placement, angle & image size control what you seek.