# Side Projection !?!?!?!



## Ikevis (Sep 13, 2009)

Someone told me they had heard of a projector that you can put at an angle, almost parallel with the screen, and it would the image would show still in a normal way, like a rectangle. I don't know much about projectors, but would this be a special lens or a whole projector that could do this? this would be perfect for our space, and we are looking for a new projector.


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## ruinexplorer (Sep 13, 2009)

I'm not sure exactly what you were told, but projecting off axis (not being perpendicularly centered) is very undesirable for projection. Certainly, the more modern projectors have options like lens shift and digital keystone correction which gives you the ability to reorient your image, but at cost to quality of your image (in the case of digital correction). We have talked about this in a few of the other threads. Essentially when you are not projecting directly on to the screen, light does what it does and creates a keystone effect. With some projectors, you can get as far as 35 degrees off of the perpendicular axis and have the projector reshape your image so that it appears to fill your projection surface correctly. This of course does not correct for the light being projected and so you will lose the even brightness over the surface of the image (the smaller portion of the keystone will be brighter than the larger portion). 

In some of the arenas, I have seen mirror units (by  High End Systems ) that attach to the front of some of the large frame projectors so that they can sit horizontal and project down onto the floor. Essentially it makes your projector into a moving light similar to adding the Rosco iCue to a Source-4. 

What situation are you facing with your projection? Maybe if you give us some more details, we can help you find a solution.


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## Ikevis (Sep 13, 2009)

Ahh. That makes sense. Well, our situation is we either need one that can project very far (like back of theater) or very steep angle down (lights on ceiling) I'm not sure if we have enough room to get RP big enough. Any one have suggestions for rear projection? That seems like it would be easiest, but you guys are the people who do this for a living. Any help is appreciated, and maybe if you live near here you can do an install for us.


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## Soxred93 (Sep 13, 2009)

If you have a little extra money, you could buy two projectors, and have them project side by side. That way, you only need to project one on half the screen.


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## seanandkate (Sep 13, 2009)

I've used a mirror to bounce the image (thereby doubling the effective throw of the projector). 'Course, then you have to compensate for weirdo flipping of the image. But if you're _close_ to having enough room for RP, that might take you the rest of the way.


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## ruinexplorer (Sep 13, 2009)

From Da-Lite's education series, here's a good explanation of how to do rear projection, especially when using mirrors. One thing to keep in mind is the type of mirror used will account for the eventual lumens on the screen. It won't be as easy, but you need to find top-coated mirrors. 

As for long throw, there are many projectors that have the lens as a separate system. With these projectors, you could most likely find one that fits your budget and the throw that you need.


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## museav (Sep 14, 2009)

I've done mirror systems, both custom and manufactured, from above, below and off to the side - all can work but each has its own issues to address. Mirror systems are usually difficult to employ in theatres where you have so much else going on. There are also electronic processors that let you compensate for a projector being way off angle but you are usually losing some resolution to make it work.

If you mean a projector that you can locate very close to the screen, there are a couple of those but they are limited in output and screen size, and thus often not sufficient for auditoria or theatres, and have to be in a very specific location for a specific screen size.

Long throw lenses are indeed an option for many projectors but are typically on the expensive side, so you would need to plan for that. Long throw lenses also often reduce the effective output of the projector, in some cases by 10% or less but in others 30% or greater, so you may also need to plan on a higher output projector if you use a long throw lens.


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## renegadeblack (Sep 17, 2009)

In terms of the angle sort of thing, not neccesarily theatre related, but this shows rear projection and even slightly behind the screen:

Johnny Chung Lee - Projects - Thesis


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## ruinexplorer (Sep 17, 2009)

Johnny Lee's work rocks. He also does some cool interactive work with Wii controllers. This is great work with mapping your projection surface, but as said before, the more you have to digitally alter your image, the less quality you get. 

Of course this is way out of budget and not completely on scope for this project, but Christie Digital has this cool (relatively) new toy call the Autostack. It allows someone using multiple projectors to easily blend or stack images.


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