Originally Posted by acras13
OK, I'm not explain what I'm looking for properly. Physically, looking at the PJ, the lens is not centered right to left, in relation to the true centerline of the PJ. Looking at the front of the pj when it is on a table it appears to be 1 1/2" or so to the right. Unless the mounting surface on the PJ is centered to the lens instead of centered to the PJ body, that would require one to offset the ceiling mount to the left of screen centerline to in fact center the image relative to the screen.
So, if I measure from my side wall, center of my screen is 63" . how far off that same wall would the center of my ceiling mount be? My instinct says the lend center would be 63"from that same side, would that place the mount center 61 1/2"?
Honestly, thank everyone for all the help, I'll drop this and just wait until I get the pj if I'm being difficult, I was just planning on getting everything ready so could just hang it and go, but it'll only take 15 minutes to do it after it gets here. Setting the image will take me considerably longer I'm sure. Sorry for hijacking.
OK...let's say the measurement between the Center point of your PJ and the Center of the Lens is 1.5"
..........and the Lens needs to be Centered at the 63" point.....
.....and the PJ is inverted.........................................................
.....and the Lens is 1.5" Left of the PJs Center when upright........................
.....the Center point of the Mount needs to 61.5" to the Left of the Center point of the Room ( 63") which is hopefully where the center of the PJ's Lens winds up.
Is there an echo here?
Of course you have already figured it out.....even if you still looking for conformation.
In truth, this is a very basic and generally understood adjustment made in all cases where the lens is offset from center on a PJ. The only variable being as to what side the lens is placed on.
But consider this...depending upon the type Mount you buy, and the degree of it's adjust-ability, the Center of the "Mount" may not be the "Center of the PJ". So always take your measurements from the "Fixed" position of a Mount tightened in place on the body of the PJ..
Because of obvious factors, such is also the time to take pains to be certain the Mount is squarely aligned with the PJ's Lens. It's not a given...and the root cause many have "unexplainable" and seemingly non-correctable trapezoidal issues.
With these exemplary "Entry Level" PJs coming in at sub $1K price points, making a wise choice as to the type of mount is absolutely critical when DLPs are involved. If you haven't made a choice of mount yet, look into a Cheif RPA-O Universal Mount. (Projector People) It can actually provide Lateral adjustments up to 1" either direction of Center. And considering that everything else discussed requires exacting placement, that last little bit of "fudge factor" can make all the difference between success...or sour grapes.