Impact using 1.33x on 4k panel projector - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 6 Old 03-09-2019, 01:11 PM - Thread Starter
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Impact using 1.33x on 4k panel projector

Impact Using 1.33 lens and 4k panel.

I'm making some assumption here because I'm new to anamorphic lenses but trying to understand why a 1.33 lens doesn't work with full 4096 panel.

if you do a digital vertical stretch you would end up with a stretch that is the same height but 3840/4096 = .9375 which is less than 1% wider.

If you add an optical 1.33 horizontal stretch to that image wouldn't all objects, head feet ect just appear less than 1% wider then if they were stretched with a full panel anamorphic lens?

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Last edited by microwiz; 03-09-2019 at 01:23 PM.
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post #2 of 6 Old 03-11-2019, 08:39 AM
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Native resolution for Ultra HD home video is 3840x2160, which measures a 1.78:1 aspect ratio. If you scale a letterboxed image vertically to fill the whole panel and then add a 1.33x lens, you get a 2.37:1 image, which is visibly close enough to either 2.35:1 or 2.40:1 that you won't notice the difference.

JVC and Sony 4k projectors have a 4096x2160 pixel panel, which measures 1.89:1. I'm not sure about Sony, but JVC at least offers two different viewing options. You can choose to watch the content at its native 3840x2160. This will leave you with pillarbox bars on the sides that you can let spill off your screen. This is a good match for a 1.33x lens.

Or you can zoom the image up to use the full 4096x2160, cropping some pixels off the top and bottom. If you add a 1.33x lens to the this, the image will be stretched to 2.52:1, which is very likely to have visible geometric distortion. What you actually need for this scenario is a 1.25x lens, such as the Panamorph Paladin DCR. Unfortunately, that's very expensive.

If you already have an existing 1.33x lens and want to add it to a Sony or JVC projector, it's best to set the projector for 3840x2160 viewing.
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post #3 of 6 Old 03-12-2019, 09:44 AM
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Quote:
Originally Posted by Josh Z View Post
Native resolution for Ultra HD home video is 3840x2160, which measures a 1.78:1 aspect ratio. If you scale a letterboxed image vertically to fill the whole panel and then add a 1.33x lens, you get a 2.37:1 image, which is visibly close enough to either 2.35:1 or 2.40:1 that you won't notice the difference.
I have a question about this scaling: what assumptions do the scalars make regarding the letterbox aspect ratio? Do they assume the image is 2.35, 2.37 or 2.39? Or do they actually detect the black pixels of the letterbox bars, and scale all of the pixels in the image area to fill the 16:9 panel? Or does it vary by manufacturer?
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post #4 of 6 Old 03-12-2019, 10:11 AM
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Quote:
Originally Posted by dschulz View Post
I have a question about this scaling: what assumptions do the scalars make regarding the letterbox aspect ratio? Do they assume the image is 2.35, 2.37 or 2.39? Or do they actually detect the black pixels of the letterbox bars, and scale all of the pixels in the image area to fill the 16:9 panel? Or does it vary by manufacturer?
Unless you do something custom, the scaler applies a 1.33x stretch vertically.
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post #5 of 6 Old 03-12-2019, 02:00 PM
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This is a frustrating situation, but you are no worse off than you were with a 16x9 projector. 1st world problems, eh?

What I think is missing on the 17:9 projectors is a 1.85:1 mode that would digitally stretch the source just enough to fill the vertical resolution and use half of the blanked out 17:9 pillar boxes, without activating lens shift. Is there a generic zoom to fill the 17:9 with a 16:9 source, cropping the top?
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post #6 of 6 Old 03-12-2019, 06:12 PM
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Originally Posted by ScottAvery View Post
What I think is missing on the 17:9 projectors is a 1.85:1 mode that would digitally stretch the source just enough to fill the vertical resolution and use half of the blanked out 17:9 pillar boxes, without activating lens shift. Is there a generic zoom to fill the 17:9 with a 16:9 source, cropping the top?

17:9 is extremely close to 1.85:1. You'd be extremely unlikely to notice the difference. And yes, they have a zoom option to crop image off the top and bottom while scaling up to fill the sides.

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