If light from the first fresnel to the second fresnel travels in a straight line, then the amount of space between fresnels and between each fresnel and the LCD panel does not matter, so long as the distance between the lamp and the first fresnel and between the projection lens and the second fresnel is correct, am I right?

So then, I can take the first fresnel (the lamp-side fresnel) and put it in the same frame as I'm building for the LCD panel, so that they are touching. Right? And as for the second fresnel (the projection lens side fresnel) I *could* have it touch the panel, too, but better to space it out if I want to do any keystoning. Right?

Thanks for any help.

Jon

Well, if you put either fresel too close to the panel, you will see the grooves of the fresnels projected with the image, best to put the first fresnel al least 10mm from the panel, and the second at least 15-20mm away (I think that's what the guide says...)

No very wrong... 1st light defuses or gets dimmer over distance, example a flashlight is brighter at a closer distance that shined at a farther distance, so putting a fresnel to far from the lcd will cause light loss. and putting the fresnel to close to the lcd you will be able to see the rings on the fresnel. this is discussed in several threads,

Why don't you just stick to the Lumenlab Guide?? This is a proven and acurate design, Use the measurments that are in there, It explains it all to you.

A terrible example, Joe. Flashlights get dimmer from a distance because the light is scattered. Light does not get dim on its own, ever, unless either the light is scattered or there is a lot of dust in the air.

With the fresnel lens directing the light in a straight path, the light does not scatter.

As for following the guide, I looked everywhere but could not see this specification. Otherwise, I wouldn't have asked.

Well i think you get my drift.....

And Look at Page 13 of the guide "Rev. 3" for the measurements.

And the light has to get dimmer at some point light is not indefinate if in a straight line... lol

Thank you for the pointer to Page 13, I see it now.

Laugh all you want, but if light is in a straight line and it does not scatter and the air is not dusty, it is called a light beam (a la "laser beam"), and it will last forever. If it fades, it is scattering or shadowing (from dust). We're not building lasers here, however, as the fresnels are not perfect, so certainly the light will fade, but that's because it is slightly scattering.

*sigh* The guys building the cabinet mounted and superglued a brace in the wrong spot and now we'll have to start over. They didn't show up today. So I'm not in a good mood, as I'm surrounded by idiots.

Xiaoth, somehow I replied to your topic here in your other topic. I see you have it resolved before I finished writing my reply.