The new PT-AE8000U projector was the thing that started this upgrade-a-palooza, so by this point I had already mounted it in the same spot as the old AE2000U -- which was a problem, because after doing a zooming test I found that it was a bit too close to reach the full width of the future 2.35:1 screen.
It had been attached directly to a joist for support, and the next closest joist was 24" away and right in the middle of the walkway. I have some tall friends including one who has hit his head on my foyer chandelier several times, so there's no way I could just move the old mount 2' back. The cable bridge I have on the walls and ceiling couldn't easily move back to the next joist, either.
There's also the issue that the AE2000U had a centered lens and the AE8000U has an offset lens. When using the old mount, the new projector's lens was not centered. Lens shift could fix this for a single lens setting, but when doing constant-height via zooming I suspected that a lens shift (which is not adjusted by the lens memory) would interfere with the zoom. I knew from testing that a vertical shift would definitely cause problems for zooming.
So I needed a new mounting system -- something that could be off-center, and positioned between joists, and closer to the ceiling to give more headroom. I built a simple adjustable system using Unistrut. The strut channel was factory-painted and I also got some rubber end caps, so it's at least less ugly than the channel they use at the office to hang conduit in the basement.
While I was at it, I also cleaned up the cable bridge by replacing the old board-and-velcro design with some strut channel that has a snap-in cover.
One piece of channel runs front-to-back between the joists and can be adjusted side-to-side to account for the offset lens.
I got a Peerless PRGUNV projector mount which is shallow and has some knobs for making tilt adjustments after everything is in place. They also make an adapter to attach a support column directly to strut channel. The column adapter can be moved back and forth on the channel to adjust the throw distance, and the height can be changed by swapping in a different column.
Right now I use a really short 3" column, but while this ensures nobody will bump their head it also puts the projector about 7" higher than it should be. I can't use the lens shift to fix it, because that interacts with the zooming and results in either the 16:9 image being too high on the screen or the 2.35:1 image being too low. So for now I have to zero the shift and then tilt the projector downward to line up the top edge, which results in some keystoning as well as slight differences in focus from top to bottom.
It's actually not that noticeable up close, but when you stand back you can definitely see the trapezoid shape at 16:9. Pulling out the masking curtains helps a lot
with that by cutting a more vertical edge into the sides of the image. There's not a lot of obvious distortion in the image itself, so once you make it hard to see that the sides are angled it's hard to tell that anything weird is going on.
I'm sure I could reduce the keystoning by moving the projector back and/or down. I had my tallest regular visitor stand underneath it the other day and it looks like I could safely lower it another 3", so that's on the to-do list.