Optoma Projector Confusion

[SteveT]

I have spent hours researching projectors and reading posts and am still confused about one potential issue specifically relating to the popular Optoma projectors that have a .5 throw ratio like the GT1080HD and GT1090HD. Since these projectors have such a short throw and indicate they should be mounted 14" above the screen for a ceiling mount, it seems like if you have an enclosure with any depth at all, the top of the enclosure would be in the way and cast a shadow on the screen. For example, if I had a 7.7 x10 x 3 Carl's DIY enclosure and one of these projectors it should be mounted about 6.5' from the screen and 14" above. That looks like the top of the enclosure would be in the way and cast a shadow. So I don't understand how anyone who has an enclosure ceiling mounts these projectors without shadow issues. Do you just mount it lower or tilt it and use keystone correction? If anyone can clarify this I would greatly appreciate it! Below is a shot from the Optoma distance calculator and the blue circle indicates the top edge of the enclosure.

[stubious]

I came across this same sort of discussion in another thread - and I think the crux of the answer seemed to be, if you have an enclosure with a frame that sticks out significantly, then BenQ may may more sense as those have no vertical offset (or very minimal). I've even seen some setups where the projector mounts to the front of the enclosure, presumably for this specific reason.

But I'd love to hear how Optoma folks have dealt with this. My setup (under construction) is going to have ceiling foam tiles instead of a 'top' to the enclosure...so that's how I'm getting around it...

[Godfather]

Yes you can mount it lower and just use keystone correction. Keystone does require the projector to be mounted slightly farther back than you may have calculated.

[stubious]

Godfather - did you find keystone impacted image quality much? How much keystoning did you have to do? I can't tell how much of it is real image degradation vs. purists in AV forums

[Godfather]

stubious I didn’t notice any difference. I had to use a decent amount. The proper height for my Optoma projector would be like 4 inches above my ceiling lol

[SteveT]

Godfather so I assume that means if you mount it higher than the offset you would have to tilt down, use keystone and move it a little forward? Specifically, if I got the BenQ TK700STi it would be behind me but to make sure it is completely out of way with no risk of shadows I'd like to mount it higher than the 9" offset (a foot or so max) and at the forward limit of it's zoom, would that work?

[mikewohlwend]

Projector Central says those units need to be mounted 14" below the top of your screen.

I did the same thing Godfather father said. I used the numbers as a reference to mount mine. I ended up being further back than the numbers said.

[mikewohlwend]

So is Projector Central wrong? Or does a negative number mean above and a positive means below?

I just looked at the Optoma site for their calculator. It makes more sense and explains why my 1080Darbee needed keystone. I am almost even with the top of my screen when I needed to be 17 1/4" higher

[wbond]

It's above, and that's what the image is showing. Top of the image is -14" below the center of the lens.

[Senorwanderer]

A negative number for the vertical offset in the calculator means outside the image, whether that is above or below. The calculator presumes a desk mount but doesn't change the -/+ when you tick the ceiling mount box.

[Senorwanderer]

I'm really appreciating this thread. This is the exact projector i'm considering and i'm fortunate to have the room to mount it the full 14" above the top of the screen. I'm actually planning on mounting a bit higher and using keystone to correct so I'm glad to know that you need to mount farther back to accommodate this. Godfather, is there a way to calculate the distance back that you need to mount for the keystone correction, or is this a trial and error situation?

[Godfather]

Depends how much keystone. Always best to estimate using the throw ratio, but verify by testing it before installing the mount and projector.

[Senorwanderer]

check out this comparison from carls place. It's almost like they were reading us!

[SteveT]

Funny, I saw that too and it made me even more undecided about which one to choose!

[SteveT]

Godfather sorry for another question but finding a perfect projector spot is difficult with my setup so now considering floor mounting one of these. With a 14” offset I’m confused how these would work well floor mounted and fill the screen. You have to tilt up and keystone? What if you move it closer to the screen than the recommended throw? Thanks for the help!

[stubious]

if the offset is 14", when sitting on the floor, your image would start 14" above the center of the lens. So if you wanted to fix that and have the image start near the floor, you'd need to tilt it down (prop up the back legs), then use keystone correction to fix the distortion.

[SteveT]

That's what I thought, Thank You!

[Senorwanderer]

AFAIK, the projector you're interested in does not require a 14" offset; an offset of as much as 14" is possible. if you were to mount the projector on the floor and the bottom of the image is at the floor you'd essentially have a 0" offset