Originally Posted by mark haflich
can't hrelp here, I do not know anything about CIA set ups. What are the advantages of CIA?
In a CIA - Constant Image Area - instead of keeping the image height constant, you keep the image area
constant per aspect ratio, so while the aspect ratio changes the shape of the image, you always have the "same sized image" for any film. Whereas of course in a CIH set up you have a significantly smaller image area for 1:85:1 and 1:33:1 aspect ratios. The advantages of Constant Image Area is that you retain a sense of cinematic immersion in all aspect ratios. This came from some member's dissatisfaction with both Constant Image Width (standard 16:9 set up as you know) and Constant Image Height, where it seemed that both approaches ended up sacrificing the size and immersion of alternate aspect ratios. (You can see this in many threads over time in the CIH forum, where people talk of "hoping a film will be in 2:35:1" and some even skewing their movie purchases to 2:35:1, because that is the most cinematic, immersive and hence
satisfying AR given their set up. The smaller 16:9 AR content feels less exciting and immersive. A certain portion of us AVSmembers wanted to avoid this issue. In a Constant Image Area set up, CinemaScope 2:35:1 films are still projected wider than the other ARs, but 1:85:1 and 1:33:1 AR films are significantly larger than on a CIH set up.
With a CIA set up you'd choose a screen closer to a 2:05 aspect screen, and zoom the image to keep a constant image area. Like CIH, if you don't mind black bars you won't bother masking. But if you DO want masked images, then of course it gets a bit more complicated with CIA because the frame edge is changing in all directions, hence 4-way masking rears it's head.
Me, I skipped right past even CIA and just went Variable Image Size. I went with as tall and wide a screen as would fit on my wall, use remote controlled 4 way masking (costs me less than a good A-lens), and zoom the image to suit the movie content, or the source quality, or how my guests like it (some love the image huge, others smaller) or just how I feel at the time. No aspect ratio is given the best treatment, they all get it, so there's never a hint of dissatisfaction with any AR for any movie.
Seems the new memory-lens-features in new projectors make CIA (and Variable Image Size) more viable than ever.
AVSmember Bjoern Roy was I believe the first advocate for CIA and explains it's genesis well in this post:
Also, his web page:
I just fell into my type of system simply because I set up a projector to project on my wall and decide what screen size and set up I'd like. Over time I realized I couldn't settle on one screen size or even CIH, and that I enjoyed the ability to make the image any darned size it felt like it needed to be. Since projection is the only display technology that allows such flexibility, I decided to retain this flexibility in my own system.
It's been the single most rewarding decision I made of all in my home theater.
YMMV, as always.Edited by R Harkness - 11/25/12 at 11:07pm