Can the field lens be further away from the LCD than the specified 20mm? if yes what would be the maxium distance before anything happens to the projection. My frames will be adjustable nut I'm asking becuase of a design change in my PJ.

Thanks

In my experience the field lens could be further than 20mm. However I don't remember how much further .

The field lens should be as close as possible to the LCD. The further away it is, the greater the chromatic distortion towards the edges. There will also be some barrel distortion introduced.

Basically, hold the lens over a magazine cover and lift it away, and observe the distortion that it introduces as it gets further away from the picture, particularly towards the corners of the lens.

More than 20mm is okay, but the closer the better. (To a point, that being where the projection lens starts getting the rings in the fresnel into focus. This will cause moire patterns to appear in the projected image.