I bought the Optoma HD65 (http://www.projectorcentral.com/Optoma-HD65.htm) for my first projector. I am looking into ceiling mounting and I had a few questions I hoped someone could answer.

1) If I want to center the image on a wall will I need to mount the projector with the lens directly centered since there is no lens shift?

2) Is the lens location exactly where the top of the screen will be or does it project on an angle?

3) I want to make my own mount. Anyone have links to something forward/back adjustable? Would I need any other adjustments? Up/down or tilt? I want to get it so I don't have to use any of the keystone since I read this is bad. Is that correct?

Please help a projector newbie. :)

I bought the Optoma HD65 (http://www.projectorcentral.com/Optoma-HD65.htm) for my first projector. I am looking into ceiling mounting and I had a few questions I hoped someone could answer.

1) If I want to center the image on a wall will I need to mount the projector with the lens directly centered since there is no lens shift?

2) Is the lens location exactly where the top of the screen will be or does it project on an angle?

3) I want to make my own mount. Anyone have links to something forward/back adjustable? Would I need any other adjustments? Up/down or tilt? I want to get it so I don't have to use any of the keystone since I read this is bad. Is that correct?

Please help a projector newbie. :)

1) Yes
2) Optoma employs a hefty amount of offset. This means the center of the lens will be above the top of your screen. How much depends on the size of your screen.
3) Ideally, you're DIY mount would be perfectly level and need no tilt to it whatsoever. That being said, you would need EXACT measurements to get it perfectly aligned. I would factor in a little bit of tilt up/down and side to side. You should be able to square the projector off fairly close to perfect but you will find that you'll need to 'play' with the projector a little to make it fit the screen perfectly.

2) Optoma employs a hefty amount of offset. This means the center of the lens will be above the top of your screen. How much depends on the size of your screen.

For people trying to decide what sort of projector to get, this point needs to be stressed when looking at DLP projectors. Most of the less expensive DLP projectors have no vertical lens shift and as noted they often have significant vertical offset requirement which can make them painful to work around in many home theater configurations. It certainly precluded their usage in my theater where the center of the ceiling mounted lens is nearly level with the top of the screen.

1) Yes
2) Optoma employs a hefty amount of offset. This means the center of the lens will be above the top of your screen. How much depends on the size of your screen.
3) Ideally, you're DIY mount would be perfectly level and need no tilt to it whatsoever. That being said, you would need EXACT measurements to get it perfectly aligned. I would factor in a little bit of tilt up/down and side to side. You should be able to square the projector off fairly close to perfect but you will find that you'll need to 'play' with the projector a little to make it fit the screen perfectly.

Probably a dumb question but is the image going to require keystone when the projector is level, because of the offset? If this is the case do I need to tilt the projector so the top of the image is in line with the lens? Based on your mount recommendation I'm assuming there will be no keystone required when the projector is level. The manual has very little information on the offset, just a chart with some numbers. No text explanations.

Also, I just noticed there is horizonal and vertical image shift in the projector menu. Is this bad to use like keystone?

The HD65 has somewhere around a 20% image offset. So for a 100" diagonal screen, the image hieght is @50 inches so the offset will be @10 inches. This means that if you ceiling mount so that the PJ lens is 80" from the floor, the top of the image will be 70" from the floor. Mount your screen so that the top of the image area is at 70" and you will be fine. You will not need to use keystone correction.

If you are using a fixed screen you can tilt the projector up slightly and tilt the top of the screen back a little to square off the image. This will allow you to have your screen higher on the wall.

Probably a dumb question but is the image going to require keystone when the projector is level, because of the offset? If this is the case do I need to tilt the projector so the top of the image is in line with the lens? Based on your mount recommendation I'm assuming there will be no keystone required when the projector is level. The manual has very little information on the offset, just a chart with some numbers. No text explanations.

Also, I just noticed there is horizonal and vertical image shift in the projector menu. Is this bad to use like keystone?

You take into account the lens shift when you mount the projector. As Reconolab pointed out, the HD65 has a 20 degree offset (I'd double check, Optoma usually has closer to 35%)...this means that the center of the lens of the projector will need to be mounted 20 degrees above the top of your screen.

Here's the real deal -- factor in some tilt in your DIY design. That way, you can take your best educated guess as to how far above the screen your projector needs to be (get it as close as humanly possible). Then fire up the projector and see how far off you are. You'll probably find that the image is off by an inch or so, one way or another (up/down, side) -- then you tilt the projector to get the image perfectly in-line with your screen. Using minimal tilt will not distort the image at all and will not require keystoning (which degrades the image...debatably). If you build your mount with no tilt function, you will need to keystone unless your measurements were EXACT...which is very, very, very difficult to do.

You mount the PJ perfectly level, the image is thrown to the screen with the offset built into the throw. For a ceiling mounted PJ, the lens will point straight across to the screen wall but the image will appear 20% (reading in the HD65 thread, this PJ is supposed to have nearly half the offset of previous Optoma PJs) of the image height below that point. So here is how I would mount in my home:

- Ceiling is 96"
- With ceiling mount, center of lens is 92" above the floor
- Offset for 100" diagonal screen with an image height of 50" is 10"
- Mount / paint / hang my screen on the screen wall so the top of the image area is 82" above the floor

If your screen MUST be a certain place on the wall for some reason, you will have to tilt your pj and use keystone correction. I would not do this but it's your PJ. I mounted my PJ and then painted my screen based on the offset, which I had already calculated for.

Take a look at this doc for a visual explanation.
http://www.infocus.com/upload/library/how_to_guide/installation/infocus_image-offset_howto-guide_installation_en.pdf

Save yourself some headache and get a universal mount that allows some flexibility in positioning the projector, especially slight left and right movements.

Also, use 2 pieces of string, of equal length, attached to the top two corners of your screen. Use them to help generate your center line.

there are very inexpensive mounts- I bought one; looked and worked like a camera tripod mount. I think it was about $40.00 including shipping. I also tried making a mount. A purchased mount will save you many hours of making changes. Unless you really want to play around making a mount. good luck!!!
there is a wealth of info on the forum and many knowledgable geek type people here to help you.

optoma has a site tha well help you compute the offset based on distance from screen(waLL)

John

thanks everyone.

Using this http://www.optomausa.com/distancecalculator.asp it looks like the offset is 19.07% of the screen height. I put in 54" height. I actually haven't made my screen yet but that is what it should be.