On September 11, 2020 at 23:43, internetraver said...
I have to be an Ernie and to ask the brand and model number of the projector?
The question he asked is a quite competent* question, so, no. That is, nothing about the variations from one projector model to another would affect what you do with one model.
It's been quite a while since I've seen a projector without some sort of lens adjustment.
Me, too. Perhaps projectors without lateral shift depend on keystone adjustment. (To look into this, get us the brand and model of the projector!)
There might be an easier fix here.
There is. Well, maybe not easier... and the entire following term paper has nothing to do with projector height. It's all envisioned as though in only two dimensions. (I first used this procedure with a Sony G90. The physical floor mockup showed us that the installation manual, which showed distance from screen to lens, actually gave distance from screen to mount. If we had followed the manual we would have wasted hundreds of dollars building a second mount. For a 240 pound projector.)
Check to be sure the screen wall is plumb. Yes, really. Decide what to do about it if it's not.
Slap tape up on the screen wall exactly along the edges of your planned image. You'll have to place it lower than the eventual image position.
Flip the projector upside down and position it such that the image edges line up with the tape. You probably won't be able to get the entire image on the wall, but be sure you get enough of it to KNOW that the edges are the right distance apart, and parallel, and plumb. This puts the lens exactly where it will be, both laterally and distance-wise from the wall.
Use a plum bob to mark the spot on the ceiling that is directly above the front center of the lens. This position is a reference from here on out.
Measure the front to back distance from the front center of the lens to the front and to the rear bracket mounting holes.
Use a laser to create two lines on the ceiling, both of which will be parallel to the screen wall. One line will be positioned at the distance from the lens position to the front bracket mounting holes. The other line will be positioned at the distance from the lens position to the rear bracket holes.
This is where you can easily go wrong, because you need to get those mounting holes dead parallel to the screen wall.
Use your above measurements to pin down where those holes are along the lines you made with the laser.
Do a test hang.
What are you doing to guarantee that all, or for that matter ANY, mount holes will be in wood? Maybe mount a piece of 3/4" ply to joists, then mount the projector to that?
Maybe do the test hang with a piece of plywood that allows you to microadjust the projector position, then transfer your correct hole positions to another piece of plywood.
*as opposed to incompetent, irrelevant, and immaterial... I've watched too much Perry Mason lately!
Last edited by Ernie Gilman on September 12, 2020 12:25.