Originally Posted by GoNavyLP
Thanks very much for the response. The joists in the ceiling are very close to the actual drop ceiling. Using plywood I think I can get the projector very close to the prescribed height. Shouldn't be too bad installing it. I'm handy enough to make it work.
It'll be hard to get it exact though so would you say the less keystone correction the better or is this the kind of thing where any small amount of keystone makes a huge difference? I ordered the 1060 and a ceiling mount that I believe I can make work so, when preparing for this, I want to make sure I'm thinking it through correctly.
A good projector mount allows you to adjust on 3 axis, X,Y, and Z or pitch, yaw, and roll. The down tube controls the height with regards to offset and in some mounts it serves as the yaw axis adjustment by pivoting the mount on the threads and locking with a set screw.
The object of mounting is to get the lens center aligned with the vertical center of the screen and perpendicular, 90°'s, with the surface of the screen. I would caution you that one of the major problems people overlook when mounting a screen and projector is that the wall the screen is mounted on is not square and plumb, at 90° with the ceiling/floor. Many walls are running on a diagonal from ceiling to floor (greater or less than 90°'s) or on the horizontal or both. I've seen walls in homes that are off by 0.5-2.0 inches or more. Many walls have a wave in the surface that can cause the screens frame to bend and or twist when it's mounted which can vary the distance on parts of the screen relative to the projectors lens causing parts of the image to be out of focus.
When you hang the screen, you want to make sure that it's level, square, and plumb in space and this may require some shimming when attaching it to the wall. Many walls are so distorted that they will bind or twist the screen frame where no amount of projector mount adjustment will allow for a correct picture geometry to be displayed.
The projector mounts 3 axis adjustment allows for correction but you want to make sure the screen surface is correct first. It's the old measure twice before you cut adage.
Quite simply put, keystone correction is intentional distortion
of the output image to create a rectangular image with regards to the selected aspect ratio. The projector does this digitally by turning off pixels on the projectors imaging panel, in your case the 3 LCD panels, to create a trapezoid (horizontal and vertical) that will match the geometry distortion created by not having the projectors lens perpendicular with the screen surface.
When the projectors keystone correction is introduced or turned on and applied, the projector has to re-scale the image to match the reduced number of pixels which in turn reduces the projectors resolution. In your case your 1080P projector is not longer 1080P when you turn on keystone correction. The sharpness of the image is also degraded from the re-scaling and the reduction of usable pixels.
So any use of keystone adjustment is an intentional introduction of distortion and a degrading of picture quality. If you're using keystone adjustment, you've done a poor job of hanging the screen and projector and acquiescing to poor picture quality as well as settling for something less than your equipment is capable of. It's very easy to avoid if you take the time to measure and carefully hang the screen and projector properly. It's really no more difficult than reading a tape measure and centering the bubble on a spirit level.