I have an infocus in72 projector mounted onto my ceiling. would you see a noticible result by moving the projector back by about 5 inches. thats how much more space i have on my celing.. the picture is not filling up the screen. just want to make sure it's worthit before i remove the toggle bolts from the ceiling.. thank you.

zooming in a bit will have the same effect as moving it back a few inches. so unless you already zoomed to the max, I wouldn't bother.

You can also try using the projector calculator on projectorcentral.com to figure out if it would be worth it or what you can do to fill your screen, which may just be too big.

Go to the Infocus web site and search for "Projection Calculator". When you find it, click "calculate image size" and you can enter the total distance from your screen to the projector lens. It will give you a range of your potential image sizes. What size screen do you have?

My screen is a 92 inch screen.. but only 80 inches is the viewable size..

Wow, must be a small room. What are the room dimensions? Are you using the zoom?

Does using the zoom affect picture quality? Would one be better off moving the projector further back or using the zoom or does it not make a difference?

Does using the zoom affect picture quality? Would one be better off moving the projector further back or using the zoom or does it not make a difference?
Zoom has no effect on picture "quality" as such. With really large screen sizes, like 133" or bigger, you might see some brightness dropoff due to zooming out to fill it in, but at your screen size, it should have no effect.