The question being, should we be trying to achieve lens shift with offsetting the triplet from the PJ centreline, or should the lens-shift be accomplished purely within the triplet lenses (or with additional lenses??)?

I'm currently using an offset field fresnel (cut down 395mm square 3dlens item) as well as keystoning the field fresnel. Initial tests are showing top to bottom focus needs a lot of work so i'd like to get away from keystoning and use all lens-shift if possible.

Any ideas I can try??

I'm using a 25% shift on my projector. The edges begin to flare out at this point but I fixed this by curling in the edges of my screen at the top two corners about 2 inches to fix the image shape. When you sit back 10 or 11 feet you really wouldn't notice the curve in the screen unless someone told you it was there. Its really unoticable and I'm not even remotely annoyed by it.

The focus at the edges is ok, not fantastic, but a thousand times better then keystoning where you get focus distortion and chromatic seperation in the image.

Really more people ought to go the lens shift route. The focus was driving me absolutely crazy with keystoning, but with lens shift I'm happy.