Handling Mixed Format 2:35 / Imax films - Page 2 - AVS Forum | Home Theater Discussions And Reviews
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post #31 of 38 Old 06-24-2020, 11:02 AM
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To each his own naturally. I personally don't care for changing aspect ratios. They've never blown my skirt up. My preference is to watch a film from start to finish where the projector screen is physically masked down to the main aspect ratio on all sides. I do this with black velvet masking. The impact is significant and best of all, it lasts for the entire length of the film, from the first frame to the last. Projecting black bars on a white screen for 99% of a given film just for the few moments when the aspect ratio changes is not worth the tradeoff for me. Again though, to each his own.
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post #32 of 38 Old 06-24-2020, 02:07 PM
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Originally Posted by rossandwendy View Post
This is always a fun topic .

In my 14 years on AVS I've learned a lot from the CIH aficionados, and also picked up great points from CIA and/or PIA fans like @Craig Peer , @R Harkness , and @bud16415 . The first 10 years of home projection I was CIW, then switched to CIH with a 2.35 screen a few years back, so I know the pros and cons of each according to my own preferences and both methods left me disappointed and frustrated. I researched a lot on the topic and considered how others had solved this like Craig with his dual screen/dual aspect ratio system, and Rich and Bud with their open palette that allows them to project whatever size they enjoy most depending on the content and audience (no different than having three rows in your home theater and choosing where you want to sit each night based on content and mood).

So when I updated my theater recently I sized my screen width for the maximum immersion I like with scope (140" inches wide and 140" viewing distance, 53 degrees), then bought a 1.78 screen with that width, and I project Constant Image Area most of the time so my scope films retain plenty of glory as they are viewed significantly wider than most of my 1.85/1.78 content, and I reserve the entire screen height for special viewings of epic changing aspect ratio films such as Dunkirk or movies that work superbly with a challenging level of vertical immersion such as Avatar, and also some of the big action films on 3D that are 1.90/1.85/1.78. Recently my wife and I watched The Aeronauts with its changing aspect ratio and it was simply awe-inspiring.

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I couldn’t have said it better myself.

In my case I saw that Craig had two screens and Rich has fancy 4way masking so just to be different I went with no screen and no masking. That also freaks my guests out.
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post #33 of 38 Old 06-24-2020, 02:24 PM
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Originally Posted by jeahrens View Post
I'd say projectors are already there for the most part. No, not all resolutions fill the 17:9 panel of modern 4K LCoS projectors. But there is more than enough resolution and light output is excellent depending on what brand you choose.
My point kind of was that with today’s resolutions of 4k the major advantage an A-lens has over zooming is in using all the light in the panel. Those that have large screen sizes and doing HDR seem to talk about the light advantage a good deal. If projector when in scope mode had a lens that could come into the light path that would vertically compress the light path down from 1.77 to 2.40 or what other AR you had it set to then that would move that advantage away from buying a very expensive 4k A-lens for those buying a projector for CIH. I actually don’t think it would be that hard to do.

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post #34 of 38 Old 06-25-2020, 08:29 AM
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Originally Posted by bud16415 View Post
My point kind of was that with today’s resolutions of 4k the major advantage an A-lens has over zooming is in using all the light in the panel. Those that have large screen sizes and doing HDR seem to talk about the light advantage a good deal. If projector when in scope mode had a lens that could come into the light path that would vertically compress the light path down from 1.77 to 2.40 or what other AR you had it set to then that would move that advantage away from buying a very expensive 4k A-lens for those buying a projector for CIH. I actually don’t think it would be that hard to do.
Optics needed to properly resolve 4K are expensive. Whether it's included or added on (and a lens that does distortion correctly like an A-lens more so). While an A-lens does give more light we're still seeing output high enough to get good results on average screens. So, while an A-lens is still giving you an advantage, we're still at a point where lens memory has made the need for a custom panel largely irrelevant. As solid state light sources evolve, I would imagine the desire for $5K+ lenses will fall even more (though those that have one will still gain benefit).

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post #35 of 38 Old 06-25-2020, 02:54 PM
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Originally Posted by jeahrens View Post
Optics needed to properly resolve 4K are expensive. Whether it's included or added on (and a lens that does distortion correctly like an A-lens more so). While an A-lens does give more light we're still seeing output high enough to get good results on average screens. So, while an A-lens is still giving you an advantage, we're still at a point where lens memory has made the need for a custom panel largely irrelevant. As solid state light sources evolve, I would imagine the desire for $5K+ lenses will fall even more (though those that have one will still gain benefit).
You are correct the very nature of all projection is based around being highly inefficient going all the way back to the first film projectors. It is based around blocking light or filtering light, so the illumination source has to have a unit brightness for the highest brightness ever needed anywhere in the image at all times and then to make colors we remove what we don’t want and to make black we remove it all. All this energy being removed can only go one place and that is into heat. Not even to mention all the waste heat many of the brightest light sources make as a waste product.

HDR specs tell us it is imposable to do with projection so they resorted to tone mapping along with some extra brightness. HDR put an even higher demand on brightness that is mainly for highlights but nonetheless has to be there for the entire image and be blocked most of the time. Thus higher inefficiency when it comes to projection.

In contrast a light emitting screen like a flat panel display has its easiest task at making black not the hardest. All it has to do to make black is not turn that pixel on thus no power.

So yes to put a lens in front of the 4k projector to pass the image thru while compressing or stretching it has to be amazingly perfect and thus expensive. My suggestion is to not do the compression after the image is formed but to do it in the light path before the image to regain that 26% that eventually has to be blocked when doing the zoom method of scope presentation of CIH. These optics I don’t think would require the fine precision as if they were passing an image. Doing this would take away the light advantage of an A-lens method of doing scope and would then only leave the resolution advantage, and many people feel at 4k resolution that advantage is not as important as it was at lesser resolutions like 720 or 1080.

You are correct most of the new projectors do fine with brightness when as you put it use a average screen. But you have to admit with HDR who wouldn’t want an extra 26% brighter image or maybe support a 26% larger than average screen. That might mean for some the difference of being able to drop to an eco lamp mode and increase lamp life.

My point was with a device that is built around inefficiencies when there is an opportunity to improve efficiency for those doing CIH presentation why not explore it.

This concept would be of no use to me of course as I need that 26% brightness over the full screen area as I like to show IMAX movies that use that area that CIH zoomers never use but pay for.

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post #36 of 38 Old 06-26-2020, 07:48 AM
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Originally Posted by bud16415 View Post
In contrast a light emitting screen like a flat panel display has its easiest task at making black not the hardest. All it has to do to make black is not turn that pixel on thus no power.
That's true only when displaying absolute black. If the "black" in the image is even one step above zero, the pixel has to be turned on and you are limited to the dark floor that pixel is capable of achieving.

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post #37 of 38 Old 06-26-2020, 07:58 AM
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Originally Posted by bud16415 View Post
You are correct the very nature of all projection is based around being highly inefficient going all the way back to the first film projectors. It is based around blocking light or filtering light, so the illumination source has to have a unit brightness for the highest brightness ever needed anywhere in the image at all times and then to make colors we remove what we don’t want and to make black we remove it all. All this energy being removed can only go one place and that is into heat. Not even to mention all the waste heat many of the brightest light sources make as a waste product.

HDR specs tell us it is imposable to do with projection so they resorted to tone mapping along with some extra brightness. HDR put an even higher demand on brightness that is mainly for highlights but nonetheless has to be there for the entire image and be blocked most of the time. Thus higher inefficiency when it comes to projection.

In contrast a light emitting screen like a flat panel display has its easiest task at making black not the hardest. All it has to do to make black is not turn that pixel on thus no power.

So yes to put a lens in front of the 4k projector to pass the image thru while compressing or stretching it has to be amazingly perfect and thus expensive. My suggestion is to not do the compression after the image is formed but to do it in the light path before the image to regain that 26% that eventually has to be blocked when doing the zoom method of scope presentation of CIH. These optics I don’t think would require the fine precision as if they were passing an image. Doing this would take away the light advantage of an A-lens method of doing scope and would then only leave the resolution advantage, and many people feel at 4k resolution that advantage is not as important as it was at lesser resolutions like 720 or 1080.

You are correct most of the new projectors do fine with brightness when as you put it use a average screen. But you have to admit with HDR who wouldn’t want an extra 26% brighter image or maybe support a 26% larger than average screen. That might mean for some the difference of being able to drop to an eco lamp mode and increase lamp life.
HDR with proper tone mapping looks fantastic on projection. And no flat panels don't always have an easy time with black. The necessity of back lighting coupled with some panel techs has a lot of the same problems that projectors face. Thus all the zone dimming that you see. The only tech that really does turn that pixel black is OLED.

While a lens would be nice, $5K on sale for a proper one just isn't going to be practical for a lot of people. Thus why you see zooming/lens memory being more common. Also with the prevalence of ARs between 2.35:1 and 1.85:1, I feel like lenses are going to need more scaling modes than what most projectors have (which is the common 2). A Lumagen can handle this, but is again very expensive. In contrast setting up a lens memory for something like 2.00:1 is very simple and effective.

Quote:
Originally Posted by bud16415 View Post
My point was with a device that is built around inefficiencies when there is an opportunity to improve efficiency for those doing CIH presentation why not explore it.

This concept would be of no use to me of course as I need that 26% brightness over the full screen area as I like to show IMAX movies that use that area that CIH zoomers never use but pay for.
How do I not use the 17:9 panel? When I play 1.78:1 or narrower material I use the full 2160 height. When I play 2.35:1 I use the full 4096 width. If I limited myself to a 1.78:1 screen I would not use the full width of the panel in a normal setup (I would be using only 3840 of the 4096 available horizontal resolution).

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post #38 of 38 Old 06-27-2020, 05:12 AM
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That's true only when displaying absolute black. If the "black" in the image is even one step above zero, the pixel has to be turned on and you are limited to the dark floor that pixel is capable of achieving.
I’m not an expert on flat panel TV designs and how much light they pass when doing very dark colors. It does seem in general for what ever the reason they are much better at stopping light leakage than projectors. I’m also sure they are not the most efficient of systems also, but if @jeahrens is correct OLED sounds to be more efficient.

My point was there is an inherent inefficiency in doing scope with zoom CIH when it comes to light output compared to using an A-lens. These projectors with automatic zoom, shift, and focus options are designed with CIH or VAR in mind and are an alternative to needing the addition of an A-lens. One of the drawbacks maybe the largest drawback now with 4k is light loss. All I was suggesting is a programmable method to condense the available light over the desired area before it reaches the imaging device rather than throwing 26% of the lamp light away 100% of the time when viewing a scope movie.

I have no clue if that can be done in a method that the other 3 adjustments are as an additional 4th adjustment. I’m not suggesting the projector has an onboard A-lens just an onboard method of condensing the light prior to the imaging device.

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