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Discussion Starter · #1 ·
I'll move out on my own fairly soon, and I've foreseen space for a PJ setup. Right now I already have a dedicated cinema room but I lack the space to put a projector. All of this is pretty far into the future stuff as moving out means spending money on non AV-related things. Nevertheless, I'm getting all fired up and I'm info hungy



So I've been reading about it all day and I hope I may ask a few Q's to clear things up in my mind. I'm sorry if this is so basic that it might drive you mad.



1. When you put up a 2:35:1 screen and you project a movie with from a blu-ray disc, the black bars get projected above and below the screen? This way your screens fills up with only the picture. Hence, you are getting 1920 * 800 resolution? Is this correct? After all, all blu rays are 1920 x 1080 but some of this resolution is devoted to the black bars (in order to keep the AR correct).


2. Since 1:78:1 content is, well, higher than the aforementioned screen size, some picture information (not a black bar but true content) is projected above and below the screen.

This sounds like trouble. How is this resolved?



Thanks for explaining this.

Jeroen
 

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Quote:
Originally Posted by Jeroen1000 /forum/post/20860088



1. When you put up a 2:35:1 screen and you project a movie with from a blu-ray disc, the black bars get projected above and below the screen? This way your screens fills up with only the picture. Hence, you are getting 1920 * 800 resolution? Is this correct? After all, all blu rays are 1920 x 1080 but some of this resolution is devoted to the black bars (in order to keep the AR correct).

True, assuming you're using the projector's zoom capability to fill the screen horizontally with a 2.35:1 (or whatever scope) AR. The letterbox bars will spill off the screen.

Quote:
Originally Posted by Jeroen1000 /forum/post/20860088


2. Since 1:78:1 content is, well, higher than the aforementioned screen size, some picture information (not a black bar but true content) is projected above and below the screen.

This sounds like trouble. How is this resolved?

Its not really, You'll have pillar bars left and right, while filling the screen vertically (hence "CIH") and NOT zooming the HD content beyond the screen top/bottom. If the bars are objectionable (visibly distracting) some folks will add black masking material panels left and right to absorb any stray room or exterior light. If the room is a bat cave, the bars may not be an issue.
 

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Discussion Starter · #3 ·
I see, I've been reading very informative thread so I did understand what you are saying.

The room will be a bat cave for sure
. It would need to be build from scratch anyway so I might as well do a good job of it.


I'll need to do a lot of catch up reading but 1 matter seems to be worth asking before I decide whether or not to save up a lot (since this is not a cheap venture by any means) of money.



I see a lot of references to scaling (in conjunction with lenses). In order to create a 2:35:1 image (of any other image that is not truly 16:9) does not the scaling imply interpolating (making up) video information that is not there?


ps: just to make sure. Such a 2:35:1 screen is wider but equally high than a 16:9 screen?
 

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Quote:
Originally Posted by Jeroen1000 /forum/post/20860372


I see a lot of references to scaling (in conjunction with lenses). In order to create a 2:35:1 image (of any other image that is not truly 16:9) does not the scaling imply interpolating (making up) video information that is not there?

Technically it is. The point being what you see on screen is now an image made of 1920 x 1080 pixels rather than an image made up of 1920 x 810 pixels when zooming. At the same height screen, the pixels are the same width (Zoomig Vs A-Lens), but vertically the pixels are 0.75x the height and there are 33% more of them in the image height.


Zooming's win here is that it keeps 1:1 pixel mapping intact.

Quote:
ps: just to make sure. Such a 2:35:1 screen is wider but equally high than a 16:9 screen?

Yes for CIH this is correct.
 

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Discussion Starter · #5 ·
Thank you mark. It's nice to have patient people around. I'm not fully understanding yet. This is probably very boring and iterative for you to get a noob up to speed
. I'm having a bit of trouble visualizing what happens.


I'll try to rephrase a more intelligble question when I can, but I fail to understand in short how a 1920 x 1080 image corresponds with a 2:35:1 screen. Wouldn't the 1920 number have to be larger.

Also, (here comes a stupid question) why use a 16:9 pj to project a 2:35:1 image?


Yep, the AR vs screensize vs resolution has me really messed up. I'm only capable picking out a nice plasma
 

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Quote:
Originally Posted by Jeroen1000 /forum/post/20861021


I'm having a bit of trouble visualizing what happens.

I've attached these images, so I might be able to better explain the process.

Original Letter Boxed image as it appears on the BD. Although the pixel matrix is 1920 x 1080, the actual image is 1920 x 810 (or there abouts). The remain space in the frame is black bars to preserve the AR.

Quote:
I'll try to rephrase a more intelligble question when I can, but I fail to understand in short how a 1920 x 1080 image corresponds with a 2:35:1 screen. Wouldn't the 1920 number have to be larger.

Also, (here comes a stupid question) why use a 16:9 pj to project a 2:35:1 image?

So when we use an anamorphic lens to project a Scope image, we must do 2 things:


1. We need to scale the image




Ok so now the image fills the full panel of the projector. There are no more black bars and the image is now made up of 1920 x 1080 pixels.


If the image was to be kept 1:1, the display would need to have 2560 x 1080 pixels. Only 1 or 2 units have this size panel, and there is still no software to support 21:9 yet, so this approach is the best we can do at this time.


2. Optic expansion by the anamorphic lens restores the geometry of the image. The image is now 78% larger than the previous letter boxed image and is the same height as a full screen 16:9 image.


Now if you zoomed the projector to do CIH (as many do), the black bars of the original letter boxed image are being shot off the top and bottom of the screen. The image on screen is 1920 x 810 (approx) VS 1920 X 1080 that can be achieved with an anamorphic lens.


The one true advantage of zoom is the 1:1 pixel mapping. If we had 1920 x 1080 images that looked like the 2nd image (AKA true anamorphic titles) we would have the best of both worlds - being 1;1 and CIH at full panel rez.


Hope that makes sense.
 

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To the common person, only 16:9 native PJs are available, which is why so many people use them. There are 2 different ways to accomplish a CIH setup, one way uses a 16:9 native PJ with an external anamorphic lens. In this senario either the PJ, Blu-ray player, receiver, or stand alone scaler performs an electronic vertical stretch of the 16:9 image from the blu-ray disc eliminating the black bars but distorting the image due to the new image being the same width as it started but now taller by 33%. The external anamorphic lens is then placed in front of the PJ's lens and stretches the new image horizontally which creates an image that is in proper proportions and is now 2.35:1 rather than the original 16:9.


The second way is by zooming, which seems like you are more interested in. In this senario you have your native 16:9 PJ setup so that the native 16:9 blu-ray movie's image is the screens height but is centered horizontally in the 2.35:1 screen, leaving left and right sides of the screen with no image projected on it. When you watch a blu-ray movie with a native AR of 2.35 or greater you will have to adjust your PJ's zoom in order to fill the screen with the full image. So, you have your 16:9 image centered in the 2.35:1 screen but now you not only have left and right sides without image but also top and bottom. You then zoom the PJ's lens to create a larger 16:9 image and when doing so the black bars on top and bottom fall above and below the viewing area of the screen and since the 16:9 image is now larger than it was before, the left and right side of the 2.35:1 screen now has image being projected onto it.


The zooming method can be tricky and tedious as it may also require you to adjust the lens shift and focus of the projector everytime you go from watching one AR to the other.


I hope that helped to clear things up on how it works, if not feel free to ask for a better description of whatever is still bugging you.


-Sean
 

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Discussion Starter · #9 ·
Excellent descriptions. I took my time to let it sink in a bit. On a high level I understand how the A-lens approach works. What I don't get is primarily scientific/theoretical and not really essential to get me going with a setup. But ... this is AVscience so I'm very interested in the theory behind things. Feel free to explain further if you guys don't mind.

I had just typed a detailed reply but there are some things I must figure out on my own before I ask rather silly questions.

But I do have some follow ups. This regarding the scaled image Mark has posted.


When you scale the 1920 * 800 image (the one with the black bars). It is scaled to 1920 * 1080 (800 + 33% is actually 1064 but it is close enough). Scaling the image this way would indeed distort it. Yep, I'm down with that.


So.... the A-lens solves the distortion and the problem that a 1920 * 1080 image is too high/tall to fit on a 2:35:1 screen. Just to make myself clear: a 2:35:1 screen is wider but less tall than a 16:9 sceen and as a consequence a 16:9 image (distorted or not) will not fit in the vertical direction.


However, I'm not quite sure what you mean by:

Quote:
If the image was to be kept 1:1, the display would need to have 2560 x 1080 pixels. Only 1 or 2 units have this size panel, and there is still no software to support 21:9 yet, so this approach is the best we can do at this time.

Is this an alternative way to solve the distortion? Because 2560 x 1080 is almost 2:35 (it's 2:37 if you make the division)
 

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Quote:
Originally Posted by Jeroen1000 /forum/post/20868217


But I do have some follow ups. This regarding the scaled image Mark has posted.


When you scale the 1920 * 800 image (the one with the black bars). It is scaled to 1920 * 1080 (800 + 33% is actually 1064 but it is close enough). Scaling the image this way would indeed distort it. Yep, I'm down with that.

Scaling is actually based on 1080 x 0.75 = 810 and 810 x 1.33* = 1080. So with a 235 film, a very slight cropping occurs and with a 240 film, very slight slivers of back can be seen. The difference is small, like 2%, but it still there on a plug-play CIH system.

Quote:
So.... the A-lens solves the distortion

This part you have correct.

Quote:
and the problem that a 1920 * 1080 image is too high/tall to fit on a 2:35:1 screen. Just to make myself clear: a 2:35:1 screen is wider but less tall than a 16:9 sceen and as a consequence a 16:9 image (distorted or not) will not fit in the vertical direction.

Not quite. The A-Lens simply expands what is already on the screen. So when you set up the projector, you do so with the full height of the native 16:9 image on screen. The 16:9 image will not fit the width of the Scope screen. The A-Lens optically expands the image to do that.


You need to remember that with aspect ratios like 1.78:1 and 2.37:1, that the 1 is the common denominator and also denotes the height and that height is the same for both ARs regardless what the CIA crowd will have you believe.


So if you take both images and put them side by side they are the same height because the letterbox is a part of the image. If you over layed them, they are both the same size (height and width) because that scaled image was captured by scaling the letterbox image. The pixel size of 1366 x 768 applies to both images because they are both screen saves from my lap top's full screen.


Quote:
However, I'm not quite sure what you mean by:

Is this an alternative way to solve the distortion? Because 2560 x 1080 is almost 2:35 (it's 2:37 if you make the division)

Adding the anamorphic lens creates an optically expanded image from the 1920 x 1080 image and makes it equal in size to a 2560 x 1080 image.
 

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Discussion Starter · #11 ·
Thank you once more for the informative reply. What I should have said is that giving the same width for both screen types, a 16:9 screen will be taller than a 2:35:1 screen. Hence, a 16:9 source on a 16:9 screen will yield a considerably bigger picture than on a 2:35:1 screen.


According to the article I have linked to below, 2:35:1 image will actually be the same size on both a 16:9 and 2:35:1 screen but on a 16:9 screen, part of the precious resolution is eaten up by black bars top and bottom.

But personally I feel the image (one with AR 2:35:1) is not really the same size because I think it is daft to count black bars being part of the image.




This is a link to the article I mentioned above http://www.projectorcentral.com/buil...ct_ratio_3.htm


One small thing here

Quote:
Adding the anamorphic lens creates an optically expanded image from the 1920 x 1080 image and makes it equal in size to a 2560 x 1080 image.

But it (expanding an image using an A-lens) does not really create additional pixels does it? You just expand the 1920 * 1080 image but the actual pixel count on the screen remains 1920 * 1080. I loosly assume a movie theatre uses a PJ with a higher resolution than 1920 * 1080. It would make sense somehow it has a native resolution of 2560 * 1080.


Anyway straying off topic for 1 moment, I will more than likely not go the lens route unless they get a lot cheaper. I hate to buy a lesser quality lens because a good one is too expensive. I'd rather not buy one at all then. I fancy both the Panny PT-AE4000 and the JVC DLA-X3. The latter will require a VP with a CMS because JVC has not included one. That is, unless I can put up with its oversaturated gamut(I guess I can as it has not really bothered me before on my plasma).
 

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Quote:
Originally Posted by Jeroen1000 /forum/post/20869365


Thank you once more for the informative reply. What I should have said is that giving the same width for both screen types, a 16:9 screen will be taller than a 2:35:1 screen. Hence, a 16:9 source on a 16:9 screen will yield a considerably bigger picture than on a 2:35:1 screen.

And why would you want that? The whole point to this section of the forum is about Constant Image Height not width. Here we have been able to think OUTSIDE the 16:9 rectangle to have something very much more cinematic than just a big TV.

Quote:
According to the article I have linked to below, 2:35:1 image will actually be the same size on both a 16:9 and 2:35:1 screen but on a 16:9 screen, part of the precious resolution is eaten up by black bars top and bottom.

But personally I feel the image (one with AR 2:35:1) is not really the same size because I think it is daft to count black bars being part of the image.

Who ever wrote the article clearly knows little on the topic. By the logic shown there, we should all be using 4 x 3 screens because at the same width, they are the largest.

Quote:
This is a link to the article I mentioned above http://www.projectorcentral.com/buil...ct_ratio_3.htm


One small thing here




But it (expanding an image using an A-lens) does not really create additional pixels does it? You just expand the 1920 * 1080 image but the actual pixel count on the screen remains 1920 * 1080. I loosly assume a movie theatre uses a PJ with a higher resolution than 1920 * 1080. It would make sense somehow it has a native resolition of 2560 * 1080

The projected image on screen is what should be used to judge this.

When using an A-Lens, you get 1920 x 1080 or over 2M pixels on screen.

When Zooming or Shrink, you have 1920 x 810 or 1.5M pixels on screen.


Given the price and limited availability of native 2560 x 1080 projectors, using an A-lens with a 16:9 projector is the best we can do at this time.


Unless these so called experts are actually prepared to do their research and actually use a high quality lens and evaluate both sides of the case, they have no right to publish articles like that. All they are doing is playing devils advocate because they know that electronics prices are falling and lens prices are not. How do they justify a $5K lens in front of a 2K projector? They can't. So they make up waffle to justify their stand.
 

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Discussion Starter · #14 ·
Thanks you all. I'm getting a much better understanding of what is involved. Josh, I actually read this article a mere hours ago. Very well written although the knowledge I got from AVS was a big help to make it easier on the brain. I recommend it as a good read for others venturing into this.


At the end of the day it will be either shrink or zoom for me (bit unfortunate but it will do just fine). Instead of an A-lens I'm, contemplating selling my DVDO EDGE an spend a bit more for an iscan DUO to get my hands on a CMS. Or I'll have to go with a PJ that has a CMS included.


So many choices ^^!
 

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Quote:
Originally Posted by Jeroen1000 /forum/post/20870742


At the end of the day it will be either shrink or zoom for me (bit unfortunate but it will do just fine). Instead of an A-lens I'm, contemplating selling my DVDO EDGE an spend a bit more for an iscan DUO to get my hands on a CMS. Or I'll have to go with a PJ that has a CMS included.

If you're going to buy a new video processor, the Lumagen Radiance Mini is a better option. It has a CMS and also full aspect ratio controls, which the DVDO Edge and Duo lack. The Lumagen is much more CIH-friendly.
 

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Discussion Starter · #16 ·
Yes, it isn't even that much more expensive. The slight bump in the road is that I still have component and composite sources. And additionally, the mini has too few HDMI inputs.


Of course I'd like the VP to upscale and deinterlace all my sources so I need a something that will "transport" my legacy sources to HDMI and provides about 5 extra HMDI inputs. All that without damaging the video signal. I'm thinking Octavia or Gefen here. If what I'm after exists, I'd prefer Lumagen. I keep hearing how good their VPs are together with their support.


I'm just a bit cautious about introducing too many devices between display and source.
 

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Just to add to the good information presented above. I look at an A-Lens purchase like I would a wedding or anniversary ring. It's something you do for life. It last decades or more. It's not something you replace yearly. I'm on my fifth preojector but only my second A-Lens, and I probably will never replace this one. However I replace projector every two years and that may continue. Regardless of the future resolution changes,as long as 16x9 chips remain, I'll be using my A-Lens to display CIH.


As far as wanting a better lens goes, thats makes sense, especially given the above. I too would Zoom before using an inferior lens.


As far as resolution goes don't get to hung up on source resolution or 1:1 pixel mapping. What I've found is source resolution, even with 800 lines, is fine(not that I won't like more), but panel resolution is in need of an upgrade with the move to larger and larger screens, and reduced view distances.


My fellow CIHer's here have a lot more experience than most. People make a lot of assumptions that aren't always based on fact or experience. When you read a car review from Road and Track or Motorweek, they typically take the car for weeks or months, even years to fully acquaint themselves with the auto and all the pro's and con's. Their review's aren't fleshed out but based on what they have experienced. Thats why this forum is such a great resource. We have been users for many years. I bought my first projector in July 2004, first A-Lens in Sept 2004 and never looked back.
 

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Quote:
Originally Posted by Jeroen1000 /forum/post/20871463


Yes, it isn't even that much more expensive. The slight bump in the road is that I still have component and composite sources. And additionally, the mini has too few HDMI inputs.


Of course I'd like the VP to upscale and deinterlace all my sources so I need a something that will "transport" my legacy sources to HDMI and provides about 5 extra HMDI inputs. All that without damaging the video signal. I'm thinking Octavia or Gefen here. If what I'm after exists, I'd prefer Lumagen. I keep hearing how good their VPs are together with their support.


I'm just a bit cautious about introducing too many devices between display and source.

Lumagen does make higher-end models with more inputs (I have the Radiance-XS). But of course they're more expensive.


(With that said, make sure you contact the sales staff here at AVS for pricing. AVS always gets a good discount.)


I used to be a fan of DVDO (as reflected in that tutorial), but the Edge and Duo are useless in a CIH application. The company has been stripping features and moving backwards with its latest products, unfortunately.
 

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