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Discussion Starter · #1 ·
I will be ceiling mounting my Barco 808s within a few months, HT completion date Jan 2002.


I was considering recess mounting it 4 inches into the existing ceiling (to get head clearance, er...my head) and tilting the projector so that the picture isn't right at the top of the wall.


The software that comes with the PJ says that it should be mounted ½ inch below the ceiling and should also be level.


Since I intend to tilt the PJ, I am considering also tilting the screen to match...towards the PJ a bit at the bottom. This will take care of convergence issues I believe.


My questions are…


Will I sacrifice anything in picture quality due to odd reflections with the angle from eye to screen and screen to PJ this way?


Is there a certain gain screen material that I should be looking for with this setup?


Is cooling the PJ a concern with it mounted with the lenses tilted slightly down?


I will likely provide a ducted exhaust line for the PJ.


Thanks,

Scott
 

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Hi Scott,


Your proposed arrangement does bring up some interesting points. Let's see if I can give you some input on a couple of your concerns:


If you pull the base of your screen away from the wall, you are compensating for the exaggerated keystone effect ( as you pointed out), but your seating position will become a factor here, as well as the height of the base of the screen from floor level. The reason is as you look up towards the screen, you are already experiencing a visual keystone effect (subtle, but it is there). Tilting the base of the screen out from the wall may make it readily apparent to the point of distraction.


As far as screen gain goes, I'd stay away from a glass bead design, as these are meant to reflect the light output from the projector back along the same axis. These types of screens work very well for table top or even floor mount type applications, but are not really suitable for ceiling mount setups.


In terms of cooling, tilting the PJ won't be an issue; restricted airflow due to the ceiling recess could be. Making arrangement for a cooling duct is a great idea.


Hope this helps, and be sure to post some pics of the finished HT!


Cheers!


Darrin
 

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Discussion Starter · #3 ·
Darrin/Dan...

I will have to do some real serious calculations to see just how far out the bottom of the screen will have to be pulled away from the wall to negate the keystone effect. I didn't realize that it might become a visual distraction, thanks for bringing that up.

I guess a few inches over a 5 1/2 foot tall screen wouldn't be too noticeable, but just how much will I have to pull it away??

That is going to be a tough one to figure out. Any mathematicians out there?

Scott
 

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It seems to me that the amount of tilt of the screen(pulled out from the bottom) is going to depend on how much you tilt the projector (lenses down back end up) from being level.


It sounds as if your going to try to keep the projection angle the same from the projector to the screen to componsate for off level mounting, in which case like you said convergance will be normal and you shouldn't have to thrown key stone out that much keeping the raster squared on the tubes.


I think you are going to have to mount the projector first and see how much out of level you will be hanging it. You can simply mount the screen at the proper height and then set the convergance up. LOOK INTO THE TUBES and see if the keystone is right then see what happens on the screen. You might be able, with some help to pull the bottom of the screen out till the image looks square on the screen. At that point take note as to the distance you pulled the screen out from the wall and shim the screen temperarily. Go sit at the normal seating area and "see" how the image looks. Does it look goofy with this arangment? if so you will be thinking of ways to correct the installation.


Maby what you can do is recess the entire projector up into the ceiling so that it is still level. Then mount the screen a little higher on the wall keeping things flat. It might be a lot of work especially mounting the projector into the ceiling. Those units are heavy and mounting is tricky!


Vic

VR Audio Systems

Phoenix
 
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