Question about switching between 16:9 and 2.35:1 without constant height

Quote:

Originally Posted by gnarlycow 

I am in the beginning stages of creating my first home theatre. However, I'm a bit confused when it comes to the projector and the different aspect ratios. I want to watch my movies in 2.35:1 format, but want my tv to be in 16:9 format. I don't want to do a constant height setup because then my 16:9 will be too small for my liking.
As far as I know, you can get the 2.35:1 by either buying a projector with a zoom lens (1.3x minimum I've heard) or by adding an external anamorphic lens. Will either of these solutions be able to change the height of the image being presented depending on the format of the video source without me having to manually change the settings? I was hoping to be able to do a motorized screen cover to block out the parts of the screen that aren't being used as well.
Assuming it is possible to do, do I just purchase a 16:9 format screen that is wide enough to fit my 2.35:1 and then just mask the screen vertically when I go to 2.35:1 format, and then mask it horizontally when I go to 16:9 mode? Is there such a thing as constant width? I've only heard of constant height setups, but never constant width. Perhaps I'm making this more complicated then it has to be.
Any help would be greatly appreciated.
Thanks,
Trevor

With similar desires as you--i.e., wanting a pic as wide as possible for 2.35, and high enough for 16x9--I went with a hybrid size screen, 144"W x 72"H, i.e. 2.0 aspect ratio.    For 16x9, I thus have a 128x72 size pic, with 'black bars' on the sides; for 2.35 I have a 144x61 (or whatever, depending on 2.35, 2.40, etc.), with 'black bars' above and below.

With 16x9 I lens shift the pic to line up with one edge of the screen and have a masking panel I slip in the other side (1.5'' think styrofoam panel, covered with ProtoStar material).    For 2.35 pics I zoom the projecctor to fill the 144" width and lens shift the pic to line up with the bottom edge of the screen, thus having a black bar at the top (which I don't bother to mask since it is quite ignorable at the top).

All the zooming and lens shifting is stored in 2 memory settings of the projector (Sony1000), so it is a very painless procedure shifting back and forth between these two modes.     Everything works like a charm and has been the wisest decision I've ever made for my setup!

Quote:

Originally Posted by Kelvin1965S 

It's 'R Harkness' you might be thinking of with the variable ratio screen with 4 way masking. He also knows how to treat a room for proper projector viewing.

Yes, it was from Rich's post a year or more ago that got me to thinking about an intermediate AR screen.     For my setup, 144" was the max width I could fit in and 72"H gave me a 16x9 pic as large as I wanted.    So this dictated my choice of a 144x72 screen; just an accident that it is exactly 2.0.

Quote:

Originally Posted by gnarlycow 


Thanks for the help everyone. I have yet some more research to do (does it ever stop?). My plan right now is to do an audio transparent screen with my speakers behind. I just like the clean look and the sound coming from the image...although I think this will cost me more to get a good screen that has the smallest holes possible as to minimize the effect on the image quality.
I think the 4 way masking is sounding like the thing I need to do the most. I'll look into exactly how that is done.
I thought that a projector was unable to project an image to 2.35:1 without an anamorphic lens. If that is true, then that is great because then I can save my money by not having to buy one of those lenses (some cars cost less!). If some projectors can broadcast all of the different aspect ratios, then is there a particular technology/feature name I need to make sure the projector has in order to hit every aspect ratio from 2.35:1 down?
One last question...if my diagonal width is approximately 144" in 2.35:1, is there a particular lumen value that I need to have minimum to be happy with the brightness (in a room with a little ambient light)?
Thanks again,
Trevor

Yes, you do need to do some more research; esp read about the 'zoom method' for doing 2.35 w/o an anamorphic lens.

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Originally Posted by BobL 

An anamorphic lens isw the best way to do 2.35, unless you have a native 2.35 projector. A poor man's way of doing 2.35 is to adjust the zoom lens of the projector to make it fit the size needed. The advantage of a an anamorphic lens is you get more brightness, more resolution and no overspray. The projector (or video processor) scales the image vertically so all the pixels are used. The lens is then placed in front of the projector stretching the picture horizontally and correcting for the vertical scaling. Because all the pixels are used the image will be brighter than if you just zoom a picture with black bars to fill the 2.35 screen. When using the zoom method your black bars will be larger than many screens frame and light up the area above and below the screen. So I would use an anamorphic lens if possible and budget allows.
To do a 144" diagonal screen with no ambient light I'd recommend a projector which can do 1200 CALIBRATED lumens in BEST picture quality mode. This would give you 24 ft/l when new and still have close to 12ft/l when the bulb is near the end of its lifespan. If you don't mind using less accurate modes or changing bulbs early you can get by with less lumens. Of course you can always use a gain screen and you won't need as bright of a projector. More is always better for ambient light. Try to keep from having your ambient light from hitting the screen and you can have a fair amount without too much degrading of the picture. Screen material can help preserve contrast for ambient light viewing. You have a lot of decisions to make:D

By having absorbant black material around the screen, the 'black bars' of 'overspill' are completely unobservant when doing the zoom method.    Putting another glass element (anamorphic lens) in the light path always compromises the optics to some extinct.

Quote:

Originally Posted by BobL 

You are correct it doesn't add any image data but you are using all the pixels and it does have a crisper picture. We have installed both methods and the A-lens is always the nicer picture. I've tested both and the benefits of the A-lens outweigh any minor negative like having en extra piece of glass. Cost is usually the issue for not doing an A-lens. Also, depending on the lens sometimes a curved screen is preferred which can add more to the cost.
Overspill can be dealt with light absorbing material. For some that is acceptable, others it is not. Depends on the room setup and decor.

I haven't tried an A-lens, so you certainly know more than I.    Another thing that steered me away from it was that I have my pj (a Sony1000) at the shortest possible throw (so that I can use my large screen in my room), and have read that this location makes for more distortion with an A-lens (unless one goes to a curved lens, as you note). Also, with the Sony1000 I have no issue with loosing a few pixels .

Quote:

Originally Posted by thebland 

Use an anamorphic lens and 2.35 screen. Side masking to use when using 16:9. E.G. CIH. No black bars again.
Ideal for all occasions. From 1.78 to 2.35 ARs.
When using an anamorphic lens. You use all the pixels on your projector and get a better sharper image.
I use an ISCO lens and a Stewart vistascope masking system. If you want the best image this is the way to go. But my lens and screen system runs over $30K retail. You can spend Large percentage less for a similar result.

Problem for me is that a 144"W (the largest my room can take) 2.35 screen would give be only 61"H, thus restricting a 16x9 pic to only ~110x61(the size of my previous screen).      The room can easily take a 72"H screen, so with my hybrid size (144x72) I get the largest 16x9 (actually 17x9 with the Sony1000) pic my room can take (136x72) as well as the largest 2.35 (144x61).     

And as noted, I do slip a 8"x72" panel (it fits right inside the screen's frame) in the left size of the screen when doing 17x9, and lens shift the 2.35 pic to line up with the bottom of the screen (with all lens shifting and zooming done with 1 button push on my URC); having a black bar at the top of the screen is not noticeable.    

I thought long and hard about all these considerations, including an a-lens, but settled on what I described.   My experience is that it is the best, and simplest,  arrangement (for me).