I just tried having the fresnels split (on each side of the lcd) and having them both on the light/bulb side.......i set everything up perfectly ......tweeked the fresnels like crazy (while leaving everything not being tested as it is) and the conclusion....


CONCLUSIONS

Fresnels TOGETHER
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* when the fresnels were together on the light/bulb side of the LCD. it produced a more in focus projection image (corners as focused as the middle)
* you lose more of the edge of the LCD (see pic) so you will need a bigger fresnel to cover the full 15" properly
* the distribution of light (over the LCD) was TERRIBLE it gave a much worse hot spot in the middle (yes everything was set up properly) .... looked like the edges of the projected image were burnt.
* cant do keystoning properly when together

Fresnels SPLIT
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visa versa of the points listed above for the fresnels together


SPLIT IS WAY BETTER THAN TOGETHER

Oops, nevermind.

I think that the standard LL fresnels are large enough to cover the whole LCD in an unsplit configuration. They need to be a bit closer to the LCD than I'd normally do, but they're certainly large enough. Only the left and right edges are in any real danger anyhow, top and bottom have more than enough leeway.

I'm also pretty sure that you CAN get reasonably even lighting, though the viewing angle of your LCD will play a factor. In theory, the lighting evenness is no different split vs. unsplit.

One other difference: Unsplit fresnels will result in longer throw. Because the fresnel in front of the LCD acts as a magnifying lens, the projected image is larger with a split configuration than it would be with an unsplit configuration. Even more so once part of the image is deliberately enlarged to compensate for keystone. This seems to be a good thing for a lot of people, so it may be something to consider.

The fresnels are 10.5 inches tall, the lcd is 9 inches tall. That should be big enough.

well my lcd is wider than my fresnels (bought a long time ago from lumenlab) so it is not possible for me to get all the left/right edges in at once ....the edge loss is even worse with the fresnels together (as show above)

so what? ...are we still in consensus about split being better than together?

i think so

with the correct FL fresnels together is way better for your reason stated in the begining the focus, and contrast also although you didnt point that out. With the 220/330 fresnels your lighting will suck you need something closer to 550

oh i c... thanks for clarifying that....so for our 220/330 combo, split is better but if u had a 550 then together would be better

also, why is contrast better?

you have a lens in front of your image? it distorts it a little while they are good lenses and I am not bashing the setup it is what I am currently running because I dont have any other fresnels having them paired together behind the lcd is the best visual setup, but you cant adjust for keystone so if you cant get your pj level it doesnt make sense to do. I have mine setup 11ft back behind my couch and it works great but the fresnel even magnifies the image a little. try putting it infront of the other fresnel you will see with your eyes the differences I am talking about, its not a small difference.

Dingle, it sounds like you have the older, smaller fresnels sold back in 2004. The newer ones are larger and clearer.

I have both, i used the smaller ones to build/experiment with, and used the newer ones for final placement. I'm glad i did it that way because i trashed the older/smaller set pretty bad; scratches, dirt, dust etc