ALR screen placement vs Projector placement - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 9 Old 12-02-2019, 04:37 PM - Thread Starter
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ALR screen placement vs Projector placement

Hey, so I have a draper react screen we're going to install and I have a Sony HW40Es for now.

in terms of ceiling mounting the PJ, is it best to mount the PJ has HIGH as I can get it. Does the til of the projector matter or can I just adjust and fix that with lens shift?
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post #2 of 9 Old 12-02-2019, 06:55 PM
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Originally Posted by aoaaron View Post
Hey, so I have a draper react screen we're going to install and I have a Sony HW40Es for now.



in terms of ceiling mounting the PJ, is it best to mount the PJ has HIGH as I can get it. Does the til of the projector matter or can I just adjust and fix that with lens shift?
The less lens shift you have to use the better. The projector should be level with Earth. You do not want any tilt.

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post #3 of 9 Old 12-02-2019, 06:57 PM - Thread Starter
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Originally Posted by skylarlove1999 View Post
The less lens shift you have to use the better. The projector should be level with Earth. You do not want any tilt.

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how come the less lens shift the better?
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post #4 of 9 Old 12-02-2019, 07:04 PM
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Originally Posted by aoaaron View Post
how come the less lens shift the better?
only using a moderate amount of lens shift, should not effect the image. A ground and polished lens is usually best in the middle and not as good toward the edges, so you want to avoid shooting the image near the edge of the lens. Also due to the curvature of the lens, you can get some distortions, as you move away from the center. You might see some of this with test patterns, but most of the time, you don't see any problems with actual material. Some projector lens are better than others and with cheaper lens, you are more likely to notice.

I should add, I am talking about vertical lens shift. You never want to use horizontal lens shift.

This was taken from a previous thread, quoting Mike Garrett of AVS Science. I agree with his statement.

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post #5 of 9 Old 12-03-2019, 07:48 AM
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Originally Posted by skylarlove1999 View Post
... You never want to use horizontal lens shift. ...
While it's best to avoid using extensive horizontal lens shift, using a small amount for fine adjustment is perfectly acceptable and will have no visible effect on the screen image.
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post #6 of 9 Old 12-03-2019, 07:57 AM
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While it's best to avoid using extensive horizontal lens shift, using a small amount for fine adjustment is perfectly acceptable and will have no visible effect on the screen image.
I can agree with that

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post #7 of 9 Old 12-04-2019, 11:59 AM
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Ditto. But don't forget you also have the option of "tilting" the screen itself in the horizontal plane. It won't be parallel to the wall behind it, but that's a lot better solution than using horizontal keystoning.
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post #8 of 9 Old 12-04-2019, 12:21 PM
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Ditto. But don't forget you also have the option of "tilting" the screen itself in the horizontal plane. It won't be parallel to the wall behind it, but that's a lot better solution than using horizontal keystoning.
Tilting both the screen and projector an equal amount from side to side or up and down to maintain a 180 degree angle between them is certainly an option. It's especially useful for projectors that lack lens shift and has none of the negatives of digital keystone correction. But if your projector has lens shift it's much easier to properly set up and will have no visible negative effect if not used at the extreme limits.
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post #9 of 9 Old 12-06-2019, 07:25 AM
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Specificlaly with his ALR question though, is there possibility of a hotspot in the middle if he's shooting the projector with no lens shift at all, vs. banked at the height of the screen and shooting down?

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