Projector offset - what if I don't match it?

[stubious]

I'm working on my first Sim build - based in the UK with short ceilings (2.54m / 8'4"). Looking at the various Optoma projectors (e.g., 1080HDR, 1090, etc.) and they all have quite a hefty vertical offset (-34cm) which isn't an issue if you have high ceilings, but a problem for me trying to maximise image height. My Screen will be 2.4m tall, but with the Optoma's offset and even a flush ceiling mount, I'm looking at a 2.1m max image height.

The BenQ ones with longer throw are too long of a throw as my garage door motor gets in the way (I'm seeing if I can shorten the track, as that would solve the issue and the BenQ would work.

But, let's say it doesn't and I have to stick with a short throw Optoma. What happens if I tilt it up slightly from level to get a big more image height and reduce the -34cm offset? Slightly skewed image that I fix with vertical keystone, right? Does that degrade quality to the point I'd rather have a shorter image? Am I missing anything?

Any thoughts/feedback appreciated!

[Gbgolfer17]

I'm a little confused on your issue, what are all of the dimensions? Are you trying to get the image to fill the whole screen? In general, the 1090 has a lot of adjustability with height and keystone correction. Other options as well: Mount next to door motor and use keystone correction to adjust for not being centered, or change garage door motor to a side mount style? I have a 1090 and am willing to do some experimenting for your if needed.

[stubious]

Here's the layout, which should help a fair bit with the visualisation. I'm hitting sideways in a garage, odd, but for various reasons, it's the only option. Green = hitting matt. The bit sticking out from the wall on the far side is the screen. The shaded triangle from the center of the projector shows that it just goes to the edge of the screen, without hitting the garage door motor, at that throw. If I push it back further, light will then start hitting the motor.

Basically, the BenQ, in theory, will give me a taller picture because it can be mounted much tighter to the ceiling (vertical offset of -5cm). But I'm hampered by the throw constraint, so I can't make full use of it. And at that throw that fits, max image height is approx 215cm.

And the Optomas all have a bigger vertical offset (approx -34 cm) - and their throw is shorter. Because of that offset, my max image height is limited by the ceiling height of my room. So I get a max 210cm image if I use the 'proper' vertical offset.

So I think the options are:
1. get the Ben Q and mount it a bit to left of center to get more throw before the motor gets in place. Or dead center and get 215cm image height.
2. get the Optoma, and mount it closer to the ceiling than they suggest, but angle the projector so that doesn't matter (but it skews the image slightly) and then fix the skew in keystone. I could get 210cm with no keystone adjustment and up to 240cm or so image height with it (somewhere in that range, the image quality difference may be noticable?)

I'm leaning toward 2, given I'm only using this for a sim (not movies/tv) and any slight degradation of quality due to keystone should be fine for my use case.

Make sense? Any thoughts/reactions?

[Gbgolfer17]

Yeah, makes more sense now, but I'm still confused. I assume you're doing 4:3 if the width is 280 and you're trying to get the tallest picture possible? It seems like either projector is really only going to give you 210cm height in 4:3 with 280cm of width, or have you not actually determined width yet?

Projection Calculator Pro - Projector to Screen Distance (projectorcentral.com)

[wbond]

It's all going to depend upon how much you tilt it and how much correction needs to be made and I don't think you'll know until you get it up, which may be a problem. If you need a lot of correction, it could make reading anything around the perimeter a problem. I have the optoma but i have high ceilings so no issue being square and no correction needed and around the edges, the wording is not as crisp as it is in the middle.

[stubious]

Yeah, makes more sense now, but I'm still confused. I assume you're doing 4:3 if the width is 280 and you're trying to get the tallest picture possible? It seems like either projector is really only going to give you 210cm height in 4:3 with 280cm of width, or have you not actually determined width yet?

Great point - I hadn't been thinking in terms of ratios, but in terms of maximum image size. So at 280w x 210h, that's 4:3 as you say. If I got more image height, I'd be heading toward 1:1 but wouldn't get there with my layout. So maybe I'm overthinking it and just keep it simple with 4:3.

[Gbgolfer17]

I think so, stick with 4:3 and choose the projector that will do that with the best throw distance for your set up. Having some space on your screen that isn't image isn't an issue, and you won't end up noticing it much.