I got a new screen ceiling mounted; perfectly align with everything else in place. When I measured the center of the screen to align the center of the lens of my HD70, I'm getting a trapezoid image. I relocated the unit about a 1.5" to the left (facing the screen) and now I'm getting a better image even dough is not perfectly square.

Has anyone else had this is issue with their units? Do I have to center the case of the projector to the center of the screen, instead of the center of the lens?

Any help is appreciated.

Center of the lens to the middle of the screen. Are three of the four sides where they should be and just one is off? Such as |_\ with a horizontal top? If you have this \_/ or /_\ , it's a keystone issue.

Also- is it going to be easier to move your screen an inch or two to the side or your projector?

Center of the lens to the middle of the screen. Are three of the four sides where they should be and just one is off? Such as |_\ with a horizontal top? If you have this \_/ or /_\ , it's a keystone issue.

Also- is it going to be easier to move your screen an inch or two to the side or your projector?

Many thanks,

Can move the screen bacuse I have a furniture stand centered behind it. I have the proper offset for my screen, 84", taking from Optoma's website.

Are you sure is from the center of lens that should be centered and not the center of the case? You see, the screen is perfectly balanced with the PJ propper offset. 16:9 looks perfect know, but 4 x 3 looks kinda sideways.

What is the best method to find the center of the screen? I'm kind of new at this.

Thanks,

Edit: My 4 x 3 looks very much like this |_\, but the other way around /_|

I'm positive it's lens and not case.

There have been numerous interesting and innovative (and some down right silly :)) ideas thrown around in this forum over the last few years for making sure the lens is aligned with and perfectly perpendicular to the center of the screen. I wish I would have bookmarked or copied some of them.

The easiest one I can think of that you could use would be to tape a piece of non-stretching thread or twine to the case right under the center of the lens. Then pull the string fairly taught and bring it to the upper right corner of your screen, mark that spot on the string with tape or just with your thumb and then go over to the upper left corner of the screen and see how that compares. Do the same with the bottom left and right corners of the screen and I bet this will show you something- perhaps that you're spot on. :) Geometry doesn't lie as long as you keep consistent tension on the string for each measurement.

Perhaps others will have some additional suggestions but I've found this method cheap, quick, easy and accurate.

Good luck..

I just eye balled my setup with out even thinking of being critical about centering, guess i got lucky, never measured the distance either.

I used a 25 foot measuring tape.

I knew about where i would need to put the PJ and mounted it to the ceiling. Then I measured from the wall to the center of the lens and then reproduced the same distance on the screen wall and centered the screen on that mark.

If you are not getting a perfect rectangle, your pj is not level, your pj is not square to the screen, your screen is not square to the pj, or all of the above.

Thanks everyone.

Its perfect know. Apparently the screen wasn't properly level. Blu Ray looks amazing!

For others with this same issue here is a thread I started about a mount I made that allows the projector to be slid right to left while in the mount.

http://www.avsforum.com/avs-vb/showthread.php?t=846744

The string idea is a good way to check it but with most mounts it’s not easy to move the projector. What most people do is rotate the projector ether with the mount or the drop tube to center the image on the screen but that’s what leads to the skewed picture on one side and sharp focus in the center and the edges slightly out of focus. Without image shift it’s important to get the lens center on the screen center.
:)