What are the practical options for projecting an image on the ceiling of a room?

Can I put the PJ on the floor, rotate it 90 degrees to point at the ceiling, and hope the cooling system holds up? Or do I need keep the PJ flat and get FS mirror?

You could build a weighted stand, much the same as a table top LCD or plasma mount and screww into the same holes normally used ror a ceiling mount plate. Hell you could get a ceiling mount plate and attach the pedastal to that. You would follow the normal protocol from projector distance to rear wall for the projector rear distance to floor. Most projectors intake and exhaust from the sides or front so there shouldn't be any problem How the optical engine and chips would hold up is another question. But I don't know all the answers.

If we are talking about a bedroom you could put it at the foot of bed down low in a foot locker kind of cabinet. Get a projector with a lot of offset. At the foot of the bed out of site sitting low it wouldn't be near your head and expose you to as much heat or noise. You probably could even aim it directly overhead if it has enough keystone control and you are willing to deal with the image degradation. A typical 7 ft throw range (assuming an eight ft ceiling) won't give you a very big picture.

No experience with this just assumptions.

I would think that only projectors with exhaust on the rear should have issues - and I'm not even sure I can think of such one off the top of my head. Just remember that you won't want the picture to be _directly_ above your head, it's actually not that comfortable to lie down completely flat, looking straight up. You will want the picture to be above your feet - and still, if it's not tilted, it will look awkward. Your brain will try to interpret the angles you're watching vs the angle you're positioned at, and tell you that something is wrong.

EDIT: BTW, I don't have direct experience, however I do have a customer who started out with the above the head idea (with a flat-panel tv), and quickly moved it towards the feet, only to find that it needed to be tilted enough as to be more like wall-mounted tilted down, than ceiling-mounted. I think it's one of those ideas that sound appealing in theory, but when you try it out you find out why nobody's doing it.

Please read the owners manual of the PJ you'll be doing this with.

My Sony VPL-VW60 has a plus/minus 15 degree mtg limit, so I'd say NO for any Sony PJ's just shooting upward.
Just my guess, you'd have to reflect the image twice so it's not backwards, and w/o good optical mirror surf you'd get other issues.
For a temp DIY hobby thing quick any mirror might show result.
http://lh5.ggpht.com/_FqTNmgNQHz8/SfcuTcQAHSI/AAAAAAAAEwA/-6ae6phAcNw/s800/PJ%20MountingAngle.JPG



I'm curious, why are you doing this?

I wanted something for the bedroom. It's uncomfortable for me to move my head too far off center, so the idea of a plasma on the wall doesn't appeal to me. The ceiling seemed like a good place.

Given the size limitation of the image with normal ceiling heights, I think you would be happier with a flat panel mounted on the ceiling over the bed.

[QUOTE=mtbdudex;16357475]Just my guess, you'd have to reflect the image twice so it's not backwards[/IMG]

Some projectors have a setting for their use in rear projection. If this setting is used, then a single 45 deg mirror can make a correct image on the ceiling.

[Since we're in the >$3000 forum, all projectors should have that setting.]

Front surface mirrors for overhead projection. In my optical opinion, the often chosen utility grade front surface mirrors aren't flat enough to assure no loss in projector image quality. They're rated 5 or 10 fringes per inch. A 1/4 wave (or 1/2 wave) mirror should be used instead.

[QUOTE=mtbdudex;16357475]Just my guess, you'd have to reflect the image twice so it's not backwards[/IMG]

Some projectors have a setting for their use in rear projection. If this setting is used, then a single 45 deg mirror can make a correct image on the ceiling.

[Since we're in the >$3000 forum, all projectors should have that setting.]

I have yet to see a projector without this...