I asked this in another thread, one specifically dealing with my Epson TW700 LCD PJ, but no one responded.

Is there a way to tell if the lens is parallel to the screen? Basically if it's level and square to the screen?

I used a small level on the bottom of the PJ, because it's mounted on the ceiling, and leveled it that way but the focus at the bottom of the screen is very very slightly out of focus, maybe I shouldn't worry because the screen is going move ever so slightly anyway????

There are several possibilities for your Focus issue.
One is that the lens itself is exhibiting aberrations on its periphery; Focus is not as precise as in the central "sweet spot" due to overall lense quality.
You may also be somewhat offset from Center, and the part of the screen that is showing this the most is where you see erratic Focus.
You will also want to make certain that you aren't using any electronic Keystone correction, as that will exhibit pronounced artifacting to the image.

You will also want to make certain that you aren't using any electronic Keystone correction, as that will exhibit pronounced artifacting to the image

as stated, urban legend.... change it to "may exhibit..."

:D

as stated, urban legend.... change it to "may exhibit..."

:D

Please put on a multiburst pattern with any fixed pixel PJ with H or V Keystone and adjust from Zero or null...your "urban legend" will manifest before your eyes.

that's one of the reasons the "may" is required.... if we spend our time looking at multiburst patterns, sure... but if, instead, we spend our time actually watching films, such an excercise will yield little evidence of artifacting until we get to some absurd amount of keystone correction, on many projectors.... some projectors though, may exhibit such artifacts on anything but zero compensation....

:cool:

Thanks but I know all this all ready, that's why I'm asking how to make sure the lens is parallel or whatever to the screen. My PJ has up and down and side shift lens so I want the PJ to be mounted with the lens facing perfectly forward and perfectly level but I don't know how other than visually.

Find the focus plane of the image. Use a 3x4 card or similar and figure out where the focus plane is and if it is parallel to your screen or not.