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How do most folks mount their projectors? If it's mounted on the ceiling, don't you have problems with keystoning? Also, it appears that most sub-$6000 projectors have digital keystone correction, but no optical correction. This seems unacceptable to me, so I'm curious what most people to.


Cheers,

Jake
 

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Just one clarification on the G series D-ILA's and keystone distortion. With a ceiling mount, an inverted projector's lense is optimally mounted with the mid-point of the lens at the same height as the top of screen (the viewable portion of the screen area, not the masking). The drop of the image to the bottom of the screen is determined by the throw distance and zoom position of the lens.



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Don O


[This message has been edited by Don O'Brien (edited 09-29-2001).]
 

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Don - thank you for the clarification regarding the JVC D-ILA's. Obviously I don't own one. I was thinking the JVC's were screen center aligned because of their success with the original Panamorph lens design. But I think the Panamorph is having most difficulty with projectors with extra offset from the top or bottom of the screen. Reed.
 

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Reed,

you are correct. If the image is edge aligned (the top of the image maintains the same measured distance to the floor along the throw path from lens to the screen surface) it should produce the least amount of distortion with anamorphic optical adapters all other factors being optimal. The JVC G series produces an image that is edge aligned.


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It all depends on the individual projector. Most of the "business projectors" have some type of "offset".


In some cases you line the projector up with the top of the screen in a ceiling mount installation. In other cases there is an additional offset from the top of the screen, 6" - 8" is quite common.


Some projectors are designed to be aimed more at the center of the screen. This is true of the Seleco "home theater" projectors and I think the JVC D-ILA's as well.


The best way to avoid keystone is always keep projector lens plane parallel to the screen plane. So mount the projector first, then locate the screen accordingly. Of course this is not always possible because of projector mounting height, screen height, throw distance, image size.....


Some slight keystoning can be acceptable if you have a screen with black boarders which will mask the problem.


This is an aspect of any projector that should be considered carefully before you buy. Reed.
 
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