Originally Posted by Ftoast
My main point against rear-projection (cheap and large) is that all those good points you mentioned about rear-pro were working because of the specially designed screen that diffused light coming from behind but NOT from the front..a plain diffusing surface (both directions) will still wash-out as light hits it from the front even with a totally darkened rear.
The screens used for RPTVs diffuse light from the back but pass it through from the front so instead of turning your blacks grey, it goes into the black pit of the inside where it's absorbed (mostly).
The good ones also tightened vertical viewing-angles while leaving horizontal angles largely untouched which meant more light made it to viewers eyes and less was wastes, all while absorbing/passing 90% of frontside light instead of diffusing 50% of it into the image.
If any of the screen companies offer an affordable rear-pro screen that functions this way, that's fantastic, but I wouldn't hold my breath. I don't even know if it's possible to make in a version that isn't stiff like a giant flat-panel.
With a plain (cheaper and pliable) diffuse screen, the lit surface being visible from both sides means your lumens are basically cut in half compared to a single-sided screen. Yes, you'll be twice as dark with ambient light hitting it because half passes through and gets absorbed, but you'll also be losing half your brightness and turning out roughly the same in the end.
A proper RP screen will simultaneously triple the amount of light making it to your viewers AND absorb 5X more frontside ambient light. I also doubt you'll find one that isn't stiff, limited to 90" diagonal or less, and under $5,000 at the size you'll want. If they exist for cheap, that's awesome!
If you can experiment with it in a controlled and affordable way beforehand, I'd be happy to be proven wrong, but I certainly wouldn't bet a big presentation on it.
This is just not the case though. Rear projection creates an environment which allows for very strong black levels in fairly bright rooms. While the use of a Fresnel lens screen was common on CRT rear projection, the use of bright projectors is far newer and allows for rear projection setups which allow a ton of light to be transmitted through the screen, at levels which produce a very strong image in a room.
The key is that the projection side (back area) must be 100% light controlled and painted dark for this to work properly.
The light certainly hits the screen and is very visible within the projection area, but the black sucks up reflections and increases contrast dramatically. This is why this is THE gold standard for rear projection with a lot of ambient light on the other side. I have been in 50+ facilities that do this, and you can just have a ton of lights on and still have a very usable on-screen image.
A material like this is what I'm talking about
1.0 gain, designed for high ambient light on the viewing side. You do have the narrow viewing angle (you described) but the surface in not terribly expensive, and with a several thousand lumen projector, you will end up with a bright punchy image in most lighting conditions (not daylight of course).
In fact, with a fast fold (portable) screen frame, this material can be ready to go for under $800.
Companies like DaLite often sell black backdrops for hiding a projector and keeping the area dark as well.