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-   -   down side to very wide screen (http://www.avsforum.com/forum/23-screens/19331-down-side-very-wide-screen.html)

Art Sonneborn 01-13-2001 10:47 PM

I've been thinking about replacing my 1.78:1 screen with a 2.35:1 ratio. I know that there will be a trade off with the reduction in resolution of 2.35:1 aspect ratio DVDs going up to that size but what are any other things I should consider. I just like the idea of only having black bars left and right.

Dean McManis 01-13-2001 11:37 PM

Art,

Do you have a digital or CRT projector?

With a digital projector the only shortcoming is lower image resolution.

With a CRT projector, you also add burn-in issues, as well as slightly lower light output and resolution.

Also some CRT FPTVs don't have the horizontal sizing control range to span from 1.33:1 to 2.35:1 (almost 100% increase).

-Dean.

Art Sonneborn 01-14-2001 09:09 AM

Dean,I have a Runco 980 ultra double stack. I saw a web site where a Runco 991 was used in a constant height aspect ratio configuration. I hoped this could be done with my setup as well. I thought since most films seem to be done in 2.35:1 aspect ratio today, that since this would then fill the screen rather than having black bars top and bottom that this might actually reduce the burn in issues? The amount of light, I hoped, would be negated somewhat by the stack. I also noticed that on that same web site that he was using a 60"x144" screen. The screen I'm using now is 61"x107".

Dean McManis 01-14-2001 12:51 PM

I think that the Runco 980 is based on the NEC XG135, but you would have to experiment around to see if you have the horizontal sizing range to make this work.

It's easy to test out. Just see if you can adjust down the picture width on your current screen to 1.33:1 width (which it should do easily), and then adjust the picture width past the edges of your current screen to the full 2.35:1 proportion, keeping the current full screen height. You can use a non-anamorphic 2.35:1 DVD to get the proportions right for testing.

As far as the burn in goes, it doesn't have to do with the screen, but the projector's CRTs. The CRTs are 4:3, with the smaller, static height image you increase the chance of burn-in and reduce brightness and resolution. But as you mention, having a double-stack, your individual projectors will be less pushed, so burn-in will be less of and issue, especially with a reasonably sized screen like yours.

So the biggest obsticle will be the sizing control range, and I know it is possible with some projectors, so you will just have to test yours out to be sure.

-Dean.

DMan 01-14-2001 04:26 PM

Quote:
I thought since most films seem to be done in 2.35:1 aspect ratio today, that since this would then fill the screen rather than having black bars top and bottom that this might actually reduce the burn in issues?
Art,

CRT projectors have 1.33:1 ratio tubes in them, therefore to use a 2.35:1 screen the vertical height of the raster image on the tube face will be reduced significantly. Overtime this will cause uneven wear (burn) in the 2.35:1 area of your tubes 1.33:1 face.

Using a CRT projector with a 1.33:1 screen and displaying only 2.35:1 movies will have the same results as using a 2.35:1 screen displaying 2.35:1 movies. The screen is the irrelevant factor here. It is how much area of the tubes raster is lit by the image area that determines the overall uneven wear, in addition to high brightness and contrast settings.



------------------
DMan
The Academy Home Theater

Dean McManis 01-14-2001 05:18 PM

DMan,

"It is how much area of the tubes raster is lit by the image area that determines the overall uneven wear, in addition to high brightness and contrast settings."

This is totally true.

But the screen is not an irrelevant factor because with a 4:3 screen, the 1.33:1 image will fill the 4:3 CRT face, but with fixed height image, the 16:9 and 4:3 image will not take up more picture height on the CRT face than the 2.35:1 image does. So the 4:3 image would potentially be half of the height to work with a fixed height screen (almost 1/4 the area), and therefore the brightness and resolution would suffer somewhat.

-Dean.

Art Sonneborn 01-14-2001 05:20 PM

Thanks guys for your responses. I would like some input on what you would do with this system. I guess the wear issue is the big one here not the fact that enlarging a DVD that only has about 360 vertical lines to play with. Is this why the constant height thing isn't as popular or is it the personal preference to have letterbox rather than windowbox. It just seems to me that this would really simplify any masking issues.

Dean McManis 01-15-2001 12:49 AM

Art,

Constant height, variable width is a cool arrangement ideally because it's just like a real theater, and as you mentioned, easier to mask with just sidecurtains.

But the reality of it is where the problems show up.

I hadn't thought of the resolution issue because I have a HTPC that scales up the 270 lines (360 for anamorphic DVDs) to match the projector's native resolution. And a quality DVD source looks pretty good even blown up fairly big.

I haven't really thought that masking is that much of an issue with CRT FPTVs because the great black level makes the letterbox bars nearly the same darkness as the black in the rest of the room, so the active image pops forward, with everything around it appearing black, including the unlit screen.

But I like the look of a widescreen, and watch a fair amount of HD material, and chose 16:9 as my screen format for both my previous CRT FPTVs and current D-ILA FPTVs. It just provides a good balance between 1.33:1 material and 2.35:1 movies.

-Dean.

DMan 01-15-2001 09:08 AM

Dean,

My point concerning the irrelevance of the screen were if Art were watching "only" 2.35:1 movies on a 1.33:1 screen this would lead to the same problems as watching "only" 2.35:1 movies on a 2.35:1 screen. This will still cause uneven wear if he does not watch any 1.33:1 material.



------------------
DMan
The Academy Home Theater


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