Does Horizontal Shift affect Image Quality - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 9 Old 01-24-2016, 12:35 PM - Thread Starter
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Does Horizontal Shift affect Image Quality

I recently purchased a jvc dla-x750r, which I love! I had an installer setup everything. The audio setup and screen mounting are great, but the projector was not mounted well. It has a fairly significant vertical shift, which is necessary for the room, but there is also about a 5 inch horizontal shift. There is not an easy way to reposition the projector. I do plan on remounting it at some point, but in the mean time, will the horizontal shift affect image quality? I've seen mixed information on this... The image is plenty bright, so I'm not worried about that. Just wondering if I'm losing anything else in terms of quality, and if it's significant or minor.

Thanks!
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post #2 of 9 Old 01-24-2016, 01:56 PM - Thread Starter
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Don't all speak up at once
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post #3 of 9 Old 01-24-2016, 02:12 PM
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Because there are threads already on this if you do a forum search.

The consensus is, so long as the lens shift is not extreme, it won't make a difference from normal viewing distance although it can depend on the lens sample. I use a slight to moderate amount of horizontal shift myself (enough to shift the image 10" with a 9 foot wide image) on my RS4810 and it made no real difference looking at pixel structure at the screen...let alone from normal seating position with content. It's pretty easy to test out.
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post #4 of 9 Old 01-24-2016, 02:17 PM
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You can inspect it yourself. Just choose your scene, examine the image, then zero the offsets, ignore the spillover and reexamine the screen. Folklore and optics recommend zero offsets. It is up to you.

Sony G90-->D-ILA--> LCD-->Vango LED DLP
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post #5 of 9 Old 01-24-2016, 06:14 PM - Thread Starter
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Thanks, I did search the forum, but saw a range of answers from "it has no impact on picture quality" to "I would *never* use horizontal shift." So, I was just curious if anyone had a an unbiased technical answer. For one thing, I wasn't sure why vertical lens shift is considered "ok" but not horizontal, other than the fact that horizontal is easier to avoid. In any case, I will test and see if I can see a difference. Thanks for the input...
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post #6 of 9 Old 01-24-2016, 06:54 PM
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Generally speaking, there is variation from center to corner of a lens.....no matter what lens and how expensive. I have camera lenses more expensive than any JVC projector, and this holds true for them as well. The extent of deviation is variable, and if lens shift moves the image from absolute center of the lens to another area of the lens, its possible that there is an effect. The best way to resolve your question, is to do what has already been suggested, perform a test.

To be honest, the question shouldn't be whether there is an impact to the image, but whether it impacts your viewing of actual content. Thus, I am not sure it matters for anyone other than those that paid a whole lot more money for "hand-picked" parts

Cheers.
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post #7 of 9 Old 01-24-2016, 08:05 PM
 
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Quote:
Originally Posted by aaronphoto View Post
Don't all speak up at once
Congrats on waiting what appears to be an hour and twenty one minutes for a response before getting frustrated.
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post #8 of 9 Old 01-25-2016, 02:18 AM
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Quote:
Originally Posted by aaronphoto View Post
Don't all speak up at once
Small amounts of lens shift in any direction will have no perceptible effect on the image. Pushing lens shift to the extreme can cause small amounts of geometric distortion.
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post #9 of 9 Old 01-25-2016, 05:40 AM - Thread Starter
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AMartin, congrats on sending a useless response.... to a not so AVS special member.

Everyone else, thank you very much for the explanations.
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