Cylindrical A-Lens Owner's Thread - Page 23 - AVS Forum | Home Theater Discussions And Reviews
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post #661 of 673 Old 06-17-2017, 07:09 PM
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I decided to pull that little CN made 1.33x A-Lens apart as it never seemed to focus. What I discovered was by flipping the lenses and adding a bit of length to the barrel, that this would focus aa sharp as my own MK5.

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post #662 of 673 Old 07-07-2017, 06:06 AM
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What patterns do you guys use to check the focus of the system?
I found these in the service menu of my BenQ to be really helpful.

One of the most annoying things to me is when text, particularly rolling credits change in focus from bottom to top. The vertical lines pattern is the easiest way to see if there is a problem. Other patterns just help prove over all focus.

NB the projector defaults to native lamp which looks really green and the camera had made those other artifacts visible.
The camera may not be showing true focus of the image.


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post #663 of 673 Old 09-29-2017, 09:35 AM
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Originally Posted by CAVX View Post
I feel the same about my cylindrical lens. It is here to stay.

It seems some of the 4K SONYs have a 17:9 imaging chip, but they can be switched back to 16:9 for use with the 1.33x lens. The full 17:9 chip requires a 1.25x lens. I'll be staying with 1080 for a while yet, though I do believe my lens will pass the full detail of UHD when I eventually make the upgrade.

Can someone help me understand this. If all 4K BD content is natively 16:9, then what's the point of a native 17:9 chip. Also, how do you use a 1.25:1 anamorphic lens on this 16:9 content without getting the wrong aspect ratio.? Finally, if I upgrade to a Sony projector with this weird aspect ratio, are there any drawbacks to using a 1.33 anamorphic lens?
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post #664 of 673 Old 09-29-2017, 11:15 AM
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Quote:
Originally Posted by CAVX View Post
I feel the same about my cylindrical lens. It is here to stay.

It seems some of the 4K SONYs have a 17:9 imaging chip, but they can be switched back to 16:9 for use with the 1.33x lens. The full 17:9 chip requires a 1.25x lens. I'll be staying with 1080 for a while yet, though I do believe my lens will pass the full detail of UHD when I eventually make the upgrade.

Can someone help me understand this. If all 4K BD content is natively 16:9, then what's the point of a native 17:9 chip. Also, how do you use a 1.25:1 anamorphic lens on this 16:9 content without getting the wrong aspect ratio.? Finally, if I upgrade to a Sony projector with this weird aspect ratio, are there any drawbacks to using a 1.33 anamorphic lens?
I'm too lazy to type it up. If you want to call I'll be happy to explain in detail. PM for number.
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post #665 of 673 Old 09-29-2017, 03:12 PM
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Originally Posted by typecase View Post
Can someone help me understand this. If all 4K BD content is natively 16:9, then what's the point of a native 17:9 chip. Also, how do you use a 1.25:1 anamorphic lens on this 16:9 content without getting the wrong aspect ratio.? Finally, if I upgrade to a Sony projector with this weird aspect ratio, are there any drawbacks to using a 1.33 anamorphic lens?
1K is the same as a bite or 1024, so everytime we have number "XK", it is a multiple of 1024.

2K = 2048
4K = 4096

4 x 3 formats like DVD were based on 720 x 540 and DVD had non square pixels to work with PAL and NTSC.

1080 is twice that of SD or 2x 540.
UHD 2160 is twice that of HD or 2x 1080.

4096 / 2160 = 1.9 not 1.78, so true 2K and 4K systems are 17:9, not 16:9.

16:9 was a compromise that supposed to represent a half way way point between 4 x 3 and Scope. Personally, I think 1.9 or even 2.0 would have been better.

The anamorphic lens allows us to use the full panel. Therefore for systems based on 1.33 like 16:9, a 1.33x lens is needed. in a 2K/4K system, a 1.25x lens is required.

The SONY projectors offer a 16:9 mode, so they back off the panel at the 1.78:1 limits. A 1.33x lens works with these systems. I have done this with one of my lenses and the SONY 520.
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post #666 of 673 Old 09-29-2017, 08:25 PM
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Originally Posted by CAVX View Post
1K is the same as a bite or 1024, so everytime we have number "XK", it is a multiple of 1024.

2K = 2048
4K = 4096

4 x 3 formats like DVD were based on 720 x 540 and DVD had non square pixels to work with PAL and NTSC.

1080 is twice that of SD or 2x 540.
UHD 2160 is twice that of HD or 2x 1080.

4096 / 2160 = 1.9 not 1.78, so true 2K and 4K systems are 17:9, not 16:9.

16:9 was a compromise that supposed to represent a half way way point between 4 x 3 and Scope. Personally, I think 1.9 or even 2.0 would have been better.

The anamorphic lens allows us to use the full panel. Therefore for systems based on 1.33 like 16:9, a 1.33x lens is needed. in a 2K/4K system, a 1.25x lens is required.

The SONY projectors offer a 16:9 mode, so they back off the panel at the 1.78:1 limits. A 1.33x lens works with these systems. I have done this with one of my lenses and the SONY 520.

Thank you CAVX. I apologize. I must have not been clear on my query. I understand all of the above. I already have a CIH setup.

What I don't understand is that the inherent ratio of both BD and UHD BD are both 16:9 and content for HDTV, BD and UHD is encoded at ratio of 16:9 (1920x1080 and 3840 × 2160 resolution, respectively), so what's the advantage of using a 17:9 panel except to monkey things up? 16:9 content (HDTV, UHD BD, BD) won't fill the whole panel (I presume it would have black bars on the sides).

I do understand that you can use these projectors in 16:9 mode but there would be these small black bars on the side and presumably black bars and overspill when I horizontally stretch that picture with my anamorphic lens.

Is there an advantage to using a 17:9 panel?

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post #667 of 673 Old 09-29-2017, 08:36 PM
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Thank you CAVX. I apologize. I must have not been clear on my query. I understand all of the above. I have an ISCO III aready.

What I don't understand is that the inherent ratio of both BD and UHD BD are both 16:9 and content encoded at ratio of 16:9 (1920x1080 and 3840 × 2160 resolution, respectively), so what's the advantage of using a 17:9 panel? 16:9 content (HDTV, UHD BD, BD) won't fill the whole panel (I presume black bars on the sides). Is there an advantage to using a 17:9 panel?

I understand that you can use the Sony in 16:9 mode but there would be these black bars on the side and presumably black bars and overspill when I horizontally stretch that picture with my anamorphic lens.
They are encoded at 16:9 yet both formats have a 21:9 option. The studios won't turn it on based on the lack of Ultra Wide TVs.

So we scale. And at 4K, 1:1 mapping is irrelevant.

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post #668 of 673 Old 09-29-2017, 10:22 PM - Thread Starter
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Is there an advantage to using a 17:9 panel?
No. This is primarily the DCI standard for commercial cinema projection. As CAVX stated 2048/4096 is commercial 2k/4k. Residential uses 1920/3840 for 2k(1080) and 4k. A 1.25x Lens is used with the DCI Resolution.
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post #669 of 673 Old 09-29-2017, 10:42 PM
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So what happens to the extra bit of image on the left and right on a 16:9 screen? Has anyone used a 1.33 lens like the ISCO III with a DCI 4K projector in 16:9 mode?
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post #670 of 673 Old 09-30-2017, 02:12 AM
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So what happens to the extra bit of image on the left and right on a 16:9 screen? Has anyone used a 1.33 lens like the ISCO III with a DCI 4K projector in 16:9 mode?
I have and it goes unnoticed. The projector blanks that portion out and then it basically gets projected off the screen.

What I did find awesome though was seeing jaggies at 4K with my MK5.

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post #671 of 673 Old 10-03-2017, 08:57 AM
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I have and it goes unnoticed. The projector blanks that portion out and then it basically gets projected off the screen.

What I did find awesome though was seeing jaggies at 4K with my MK5.
Is this a problem with the scaling in the Sony?
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post #672 of 673 Old 10-03-2017, 05:19 PM
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Is this a problem with the scaling in the Sony?
Yes and no. The Sony locked up when fed UHD but the OPPO 203 was able to apply VerticalStretch.
The jaggies showed that my lens is truly transparent as it resolved pixel level clarity at true 4k rez. I was impressed.

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post #673 of 673 Old 10-04-2017, 03:07 PM
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Here is the setup with the MK5 and Sony520.

The Sony wants to scale the image to fit the fill 4096 with. This means it generates only 20% black bar and not the normal 25% of the 2160 vertical rez.

Even thought there are a choice of either 1.24x or 1.32x in the set up menu, as soon as it detects a UHD signal, it wants to remap as if zooming was the only option. No stretch. Probably a carry over from the DCI and D-Cinema which all zoom now.

So if you want to use the full 17:9 chip for Scope, you would need the 1.25x version of my lens (which came available last year) but you also need the ability to custom scale as even the OPPO is still based on 1.33x, not 1.25x.

As far as I know, there is just one scaler that can do this and it is about $6K.
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Last edited by CAVX; 10-04-2017 at 03:12 PM.
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