Originally Posted by DrNegative
Unless you have an anamorphic lens, the HD20 will only put out a native 16:9 image.... regardless of what ratio the content is. And you want to try to avoid using keystone adjustments, if possible.
Just like DrNegative mentioned already. The HD20 is native 1920x1080 16:9 widescreen. So 1.85 to 2.4 ratio content will have equal black bars top and bottom with the image center. And lower than 1.78 will have equal black bars left and right with the image centered.
On rare occasion I have seen some DVDs that were poorly mastered so the player (not the HD20) thinks it's 1.33 content, but it's really widescreen content with encoded black bars. In that rare case, you end up with black bars around all 4 sides and a much smaller movie in the center. But that is rare.
And to repeat what DrNegative said. Avoid digital keystone correction. While the HD20 does do a good job, it does reduce the number of pixels displayed and alters the sharpness and quality of straight lines, etc. Especially if you ever do gaming or connect a computer up.
If you keep the projector square to the screen, you will not need any keystoning. Use the Projector Central calculator to figure out the image offset in inches for your screen size and projector distance. Remember the distance is from the front of the glass of the lens to the screen.