Who has a ceiling mount PJ and tilted it so as to use less keystone? Or has not had the correct relationship with their PJ to the top of the screen and corrected for it?

What I'm going to do is move my PJ down (more towards the center of the screen). Now if it was centered on the screen I would just do it like the manual shows for a rear projection setup, except it would be upsides down as it would still be ceiling mounted. You would have to correct the flapping and move the image to recenter it, is that all there is to it? Should the back of the PJ tilt down the more it's moved towards the center of the screen?

Are there any issues with doing this?

What I'm doing is setting my PJ up to run on my HP screen. I'm lowering it off my ceiling to a minimum comfortable height and putting my seats on platforms. This seems like the best trade off, the PJ is not so low as to be a head banger when walking around and raising the seats will get the viewing position into the sweet spot for the HP screen.

Thanks, Deron.

Keep the tilt the same as you lower it then drop down the back of the projector till the top of the image is at the top of the screen then set it there and redo all your geometry settings I think is the easiest way to do it. as long as your distance renmains the same.

Athanasios

Without the slant the path length will decrease, so you'll end up with needing to either use a larger phosphor area, or moving the projector back somewhat. As described in most manuals.

Who has a ceiling mount PJ and tilted it so as to use less keystone? Or has not had the correct relationship with their PJ to the top of the screen and corrected for it?

What I'm going to do is move my PJ down (more towards the center of the screen). Now if it was centered on the screen I would just do it like the manual shows for a rear projection setup, except it would be upsides down as it would still be ceiling mounted. You would have to correct the flapping and move the image to recenter it, is that all there is to it? Should the back of the PJ tilt down the more it's moved towards the center of the screen?

Are there any issues with doing this?

What I'm doing is setting my PJ up to run on my HP screen. I'm lowering it off my ceiling to a minimum comfortable height and putting my seats on platforms. This seems like the best trade off, the PJ is not so low as to be a head banger when walking around and raising the seats will get the viewing position into the sweet spot for the HP screen.

Thanks, Deron.

Do it Deron - just need to compensate with flapping. I'm not sure how PG10 flapping works, can you go in between steps?

Mark, the 10PG has no flapping. I did shim my green and red lenses with some .010 plastic to correct the left edge. The blue was good.

I guess the best bet is to build my new mount so the PJ can be adjusted easily. I will try with the back of the PJ lower then the front, see how it looks with minimum keystone and where the rest of the settings end up at. The PJ should end up about a third of the way down into the image area on the screen.

Deron.

Deron,

How did you end up lowering the projector while still being able to move it back and forth? I want to do this with my XG because I'm anal about keystone, but I'm having trouble devising a good way that's relatively simple, sturdy, and able to move the projector back and forth. I was thinking just using longer bolts from where the XG mount attaches to the unistrut, but this would make moving the projector back and forth more difficult.

Deron - fwiw, I've been running my 980 U for over a year that way - asked here, folks said go for it, so I did. I had to adjust the flapping, but after that it was fine. My lens faces are parallel to the screen, and everything is quite happy. Plus, in my room, it was the only way to make things work. :)

Jon

I used two pieces of unistrut bolted to the ceiling, two pieces of unistrut holding the PJ by way of the feet (I replaced the feet with bolts and washers) into the long slots, four pieces of all thread with nuts and washers on one end ending up in the slots of the unistrut at the ceiling and then the all thread went into the mounting holes on the unistrut that is on the PJ.

I can adjust the PJ up and down by way of the all thread and the feet on the PJ. Side to side is by way of the unistut on the ceiling and front to back is by way of the unistrut on the PJ.

The all thread can be made to any length you want for your height. My PJ is just above my head, anyone taller then 6' may have a problem.

I removed as much Keystone as I could. The limiting factor was the image would not reach the bottom of the screen if I tilted the back of the PJ down too far so I could remove all the Keystone.

Deron.

Is this how it looks? If not, could you take a picture or make one up in paint? I'd really appreciate it.

http://www.avsforum.com/avs-vb/attachment.php?attachmentid=93531&d=1193975757

Hi,

the 10PG needs to be parallel to the ceiling (in a normal room that is :)) or else there are problems with Scheimpflug - the 10 PG has fixed Scheimpflug and will have very bad top-bottom foucs on green when perpendicular to the screen.

There isn't really any way to work around this other than slaughtering some housings of a projector with decent stepless Scheimpflug.

The other option is to conjure up a Scheimpflug system similar to what Ampro did - not a good idea IMO. Chip who has an Ampro is about to replace his Ampro housings for Marquee housings because they don't work.

Oliver

So you're saying making the angle around 8° is going to make proper focus impossible on an XG?

Jeff - that is sorta how mine is - only in reverse. Mine is mounted upright - as in table mount, or shelf mount. But hanging from an angled, cathedral ceiling. So if you turn your picture upside down, set my pj on a shelf - represented by the red unistrut, then have a threaded bolt on each corner supporting the shelf. But if I leave the projector level, the image is either way too high, or way too low. So - secured the pj to the shelf, and then raised the rear until tube faces are parallel to the screen - which also put the image in just the right place.

Oliver - ot - but just got my Ampro - will it not focus in this orientation? I'm still incredibly naive - figured if my NEC would work that way, anything would. Dang - hope it has enough adjustment - an out of focus 9" isn't any better than a nice, sharp 7+"r.

So you're saying making the angle around 8° is going to make proper focus impossible on an XG?

The comment was on the 10PG that has fixed Scheimpflug and no lens spacer corrections.
The XG is not fixed and has spacer tab adjustments to change projection angle from factory optical core for ceiling. If your tilting out of the level position because of install limitations you will need to work a bit with this (angle and tabs) using the screen and focus H pattens so the top and bottom are the same or within correction limits. You want to start with null edge focus adjustments and work out from there. The electronic astig also needs to be considered. End result is uniform focus over the entire screen.

Line of sight and the reflected image angle needs to be noted. Sometimes level can be maintained then worked out. This is up to you, your room and your patience level.
Big can of worms on this between different makes and models and what each application is requiring. RP, mirrors, raster maxing etc. Doug

Jeff

That is not the way I did mine, but it does not matter, as long as you have the Unistrut set up so you can slide the PJ side to side and towards or away from the screen it will work.

If you use the threaded holes in the PJ where the feet used to go in, you will have to come up with metric all thread or weld some metric bolts onto the all thread.

What you need to do is find out which way the ceiling joist run and attach your Unistrut perpendicular to them, then you can attach the next set of Unistrut to the ceiling Unistrut. On the Unistrut that gives you movement towards or away from the screen, make them plenty long, this is where you will likely do the most adjusting now and in the future. This can come about with screen size changes and using different amounts of the tube face.

Deron.

Oliver

The 10PG's flapping can be adjusted, just break out the shims. In fact when I did have a XG 1100 and a Sony 1272, I found the stepped flapping adjustment to be so course that I used shims to get the focus perfect. When you can change focus just by the amount of torque on the screws, stepped flapping can be a long way from perfect.

Deron.

I bolted unistrut to the pj with the metric bolts and then ran allthread up to the unistrut above the rafters from there. Seems to work really well, the front/rear and side/side adjustment is a breeze. The up/down and angle is just a matter of running the nuts up or down. Cut the allthread long enough for your adjustments.

Jeff

That is not the way I did mine, but it does not matter, as long as you have the Unistrut set up so you can slide the PJ side to side and towards or away from the screen it will work.

If you use the threaded holes in the PJ where the feet used to go in, you will have to come up with metric all thread or weld some metric bolts onto the all thread.

What you need to do is find out which way the ceiling joist run and attach your Unistrut perpendicular to them, then you can attach the next set of Unistrut to the ceiling Unistrut. On the Unistrut that gives you movement towards or away from the screen, make them plenty long, this is where you will likely do the most adjusting now and in the future. This can come about with screen size changes and using different amounts of the tube face.

Deron.

I'm just changing screens now, and I will need to move the projector 1.5ft forward due to a smaller screen. This means I have to redo the ceiling mount since I did not account for this much adjustment in the original mount. But since I have to redo things, I might as well try and make it so I have to use as little keystone as possible.

The tricky part will be in setting the lense flapping, but the XG AC manual is weird. The flapping settings are the same when going from 0° angle to 12.4° angle at the same widths. It changes much more with LC though. Does this mean that the flapping settings are less important on AC sets than LC sets? And what am I looking for exactly when setting flapping... uniform lense focus across the entire screen?

edit: nvm... i missed Doug's post.

Oliver

The 10PG's flapping can be adjusted, just break out the shims. In fact when I did have a XG 1100 and a Sony 1272, I found the stepped flapping adjustment to be so course that I used shims to get the focus perfect. When you can change focus just by the amount of torque on the screws, stepped flapping can be a long way from perfect.

Deron.

Deron,

a proper Scheimpflug system has to be implemented so that it is possible to adjust the angle between the optical system and the tube. In the case of the 10 PG this is not possible as you have to break up the optical system between the C-element and the lens - in all proper Scheimpflug applications the movement is between the c-element and the tube face and that is not possible with the 10 PG. You might still be able to do a few small adjustments without detrimental effects but this only works up to a certain point.

From my experience this is not really a problem if you stay at the proper angle with a screen width of around 7 to 12 ft wide, I achieved great results that way. But it will NOT work when the projector is at a much shallower angle to the screen than what it is designed for.

Oliver

Oliver - ot - but just got my Ampro - will it not focus in this orientation? I'm still incredibly naive - figured if my NEC would work that way, anything would. Dang - hope it has enough adjustment - an out of focus 9" isn't any better than a nice, sharp 7+"r.

I think perpendicular to the screen is the only orientation that works with the Ampro, so you will porbably do fine on green with a bit of side Scheimpflug missing on red and blue.

But you tell us what you see once you play around with your new toys :)

I think perpendicular to the screen is the only orientation that works with the Ampro, so you will porbably do fine on green with a bit of side Scheimpflug missing on red and blue.

But you tell us what you see once you play around with your new toys :)

I will, I will...I haven't had time to do much except walk around the puppies. As someone said in another post, they are indeed butt-ugly. I can't wait to get one (or two) hung so I can turn out the lights, and look at what they do, instead of their danged cases.

But they are SOOOO heavy. Anything that can make a 980 look light...;) (and petite.)

As someone said in another post, they are indeed butt-ugly.

Quoted for truth :D
Sorry, couldn't resist, after all it's of course the picture that counts :)

Oliver

I never follow the rules, I'm one of those types that needs to try it myself before I believe it can not be done on whatever it is. The shims did work for correcting focus problems on the sides of the green and red, I only used about .01" though, not sure how far you can adjust it without having problems like you said. I wonder why the 10PG does not have flapping like all the other PJ's do?

Deron.

Oliver

I never follow the rules, I'm one of those types that needs to try it myself before I believe it can not be done on whatever it is. The shims did work for correcting focus problems on the sides of the green and red, I only used about .01" though, not sure how far you can adjust it without having problems like you said. I wonder why the 10PG does not have flapping like all the other PJ's do?

Deron.

Deron,

I am not exactly playing by the rules myself all the time - see my 10PG with a plus chassis and electronic astig ;)

So I tried the Scheimpflug thingy myself two days ago and it looks surprisingly good - definitely better than not using it, so you're good to go :)

While there are good scientific reasons why this should not work the 10PG surprised me again - I am very pleased !

As for not using Scheimpflug: This is a 93 design and back then I think nobody really had proper Scheimpflug for LC units, at least the other 9" units from Barco and Sony didn't.

Oliver

Oliver

Our 10PG's are so good I forget that they are that old and I end up comparing them to what is the latest and greatest:)

The only thing I can think of is they must have though the set up and manufacturing tolerances would be close enough, NOT, they just did not think it justified the extra money a Scheimpflug would cost.

Deron.

Oliver

Our 10PG's are so good I forget that they are that old and I end up comparing them to what is the latest and greatest:)

The only thing I can think of is they must have though the set up and manufacturing tolerances would be close enough, NOT, they just did not think it justified the extra money a Scheimpflug would cost.

Deron.

I think that NEC did not give these things much thought back then. They would have needed stepless Scheimpflug with a rubber Element and they only got there 4 years later but then only with the suboptimal construction they got in the XG.

BAck then the 10 PG was really meant for both more light and more resolution and it was constructed to last many hours. Doug once said that he has seen most of them in military applications.