I'm building a home theater addition and plan a 120" 16:9 rear projection screen. The "projection room" is 10 feet deep. I've been studying the forums and fiddling with Focal Calc II looking for ways to fit into the space (with or without a first surface mirror).

Increasing the Fresnel Gap shortens the Screen Distance, but at what cost to quality? Most designs are showing 20mm, but what if I use 200mm? Also, what about using the 330mm fresnel for the field lens vs. the 650mm?

I just found LL a few days ago and am getting really excited about a DIY alternative to the Sony VPL-VW100 ($6K+ and $900/bulb!)

Mr Bubba

read up on using split optics,, and use focal calc to get screen size to distance..

the front field fresnel increases the size of projection, and works quite well,, I am unsure about going out as far as 200mm,,

I have about the same distance,, and very shortly will be doing same as you with a PRO lens set,, so will be going to split as one test,, and possibly will set a big distance on the fresnel to lcd

I've ordered the Pro lens kit and will experiment with field lens to LCD distance before getting the first surface mirror. At 24"x42", it would be a big expense I would rather avoid.

My concern with the bigger distances between field and LCD is light loss as it seems the coherence of the light coming though the LCD can't help but be disrupted somewhat by passing through the LCD.

Mr Bubba

I don't know if this would work I know this is what they do for DLPS to increase luminosity. You could attach high watt bulb in between the screen and mirror. This would most likely increase brightness but it may drowned out some of the image. Sounds like an experiment to me!