New 8k and 4k a-lens from Panamorph - Page 2 - AVS Forum | Home Theater Discussions And Reviews
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post #31 of 35 Old 06-08-2019, 08:31 AM
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Originally Posted by jabz View Post
Hi, I don't get this and I have seen it a number of times, I'm sure its due to my limited understanding however would appreciate someone explain it. I have a Prismasonic Cylindrical lens, which I am using with my Sony 520ES 4K Projector. How is my lens not using the full 4096 x 2160 panel vs a DCR lens which claims to?
You can use 4096 x 2160 on your Sony. If your lens is a 1.25x ( like the DCR lens ), you will get the correct aspect ratio using 4096 x 2160 ( and 6% more brightness ). If your lens is 1.33x, you should use 3840x2160 for the correct picture geometry.
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post #32 of 35 Old 06-08-2019, 05:47 PM
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Originally Posted by jabz View Post
Hi, I don't get this and I have seen it a number of times, I'm sure its due to my limited understanding however would appreciate someone explain it. I have a Prismasonic Cylindrical lens, which I am using with my Sony 520ES 4K Projector. How is my lens not using the full 4096 x 2160 panel vs a DCR lens which claims to?
The way i try to understand the meaning of that 6% is.... that there is ~6% more light and resolution is the difference between the use of the full 4096 vs only the 3820 horizontal resolution when using these native 4K projectors.

Most A-lenses have the 1.33x horizontal stretch or similar 1/1.33 > ~0.75 squeeze ratio to be used with 16:9 AR projectors @ native 3820x2160 source resolutions.
To get the correct aspect ratio when using the projectors full native 4096 x 2160 resolution that is wider than the 16:9 format, the A-lens need to only have 1.25x stretch or 1/1.25 > 0.8 squeeze.

There may also be some different in light output when using an A-lens that squeeze the height of the picture vs a stretch lens. Particularly when the projector is used at the same throw distance from the screen. The reason is that with a squeeze A-lens, the projector lens is uses more in the wide angel part of the zoom that often have a higher light output from the same throw vs the the less zoomed projector lens, used together with a horizontal stretch A-lens.

If your Prismasonic Cylindrical lens have the 1.25x stretch factor so your Sony can use the full native resolution and get the correct AR on the screen, then you already have that positive 6% light and resolution.

Edit: looks like I was a little late with this reply....
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post #33 of 35 Old 06-23-2019, 07:28 PM
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Originally Posted by Craig Peer View Post
You can use 4096 x 2160 on your Sony. If your lens is a 1.25x ( like the DCR lens ), you will get the correct aspect ratio using 4096 x 2160 ( and 6% more brightness ). If your lens is 1.33x, you should use 3840x2160 for the correct picture geometry.

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Originally Posted by ask4me2 View Post
The way i try to understand the meaning of that 6% is.... that there is ~6% more light and resolution is the difference between the use of the full 4096 vs only the 3820 horizontal resolution when using these native 4K projectors.

Most A-lenses have the 1.33x horizontal stretch or similar 1/1.33 > ~0.75 squeeze ratio to be used with 16:9 AR projectors @ native 3820x2160 source resolutions.
To get the correct aspect ratio when using the projectors full native 4096 x 2160 resolution that is wider than the 16:9 format, the A-lens need to only have 1.25x stretch or 1/1.25 > 0.8 squeeze.

There may also be some different in light output when using an A-lens that squeeze the height of the picture vs a stretch lens. Particularly when the projector is used at the same throw distance from the screen. The reason is that with a squeeze A-lens, the projector lens is uses more in the wide angel part of the zoom that often have a higher light output from the same throw vs the the less zoomed projector lens, used together with a horizontal stretch A-lens.

If your Prismasonic Cylindrical lens have the 1.25x stretch factor so your Sony can use the full native resolution and get the correct AR on the screen, then you already have that positive 6% light and resolution.

Edit: looks like I was a little late with this reply....


Ok thanks or the replies and explanation, I have a 1.33x lens. Would using a 1.25x lens even make a difference for 4K UHD Movies as they are all 3840x2160?

J

Sony VPL-VW520 | Elitescreens TT 135" 2.35:1 | Elitescreens TT 120" 16x9 | Prismasonic HD-6000F | Onkyo TX-RZ3100 | Oppo UDP-203 | PS4 PRO | ATV4K | LG OLED 65 C7 | Klipsch Reference RP-280 | Klipsch Reference RP-280C | Klipsch Reference RP-250S | Klipsch Reference RP-150M | Klipsch Reference R-115SW | Klipsch Reference R-140SA
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post #34 of 35 Old 06-24-2019, 07:07 AM
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Originally Posted by jabz View Post
Ok thanks or the replies and explanation, I have a 1.33x lens. Would using a 1.25x lens even make a difference for 4K UHD Movies as they are all 3840x2160?

J
Yes there will be a little difference for 4K UHD scope movies that only make use of the ~3840x1600 active cinema picture on the disk, the 1.25x A-lens will when the source is digitally stretched correctly, use the entire 17:9 (4096 x 2160 pixel) format in the projector.

The 1.33x A-lens will only make use of the 16:9 (3840x2160) part of the 17:9 light engine....
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post #35 of 35 Old 06-26-2019, 11:02 AM
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Originally Posted by jabz View Post
Ok thanks or the replies and explanation, I have a 1.33x lens. Would using a 1.25x lens even make a difference for 4K UHD Movies as they are all 3840x2160?

J
Watching 4096 x 2160 adds 6% more brightness vs 3840 x 2160 ( and more pixels ). So if you have a large screen, are struggling for light, or just want as bright a UHD picture as possible, every bit helps !
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