Does anyone have a suggestion for correcting my triplet image barreling?
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I'm using a 14" FL Beseler lens (4" diameter). The focus is pretty good and the field of view is large enough for my 10.6" panel. It just has a very slight bloating effect on the projected image.

I found the link below where elkin fixed pincushion in the 1st generation pro-triplets. Would I add more space instead of less space to correct a barrel or bloat?

http://www.lumenlab.com/forums/index.php?s...st&p=168481

Which lens would I want to move? collector on the retaining ring side?

Any thoughts will help, I may just live with it as it doesn't affect the viewing experience or focus too much. I don't believe it's a fresnel problem since I've tried split and unsplit configs with the same result.

No triplet gurus around today?

Your post got me thinking and curious about the very same lens I had sitting in a box in my basement, calling me in a sweet voice that said "come play with me, I'm so pretty."

So I pulled off the focus sled on my box and held the Bessy in front, with the labeled end of the lens facing towards screen, and .... saw very similar barreling to what you describe.

For sh^ts and giggles I flipped the lens, end to end, so the labeled end faced the lcd. Unless I'm stone crazy, the barrelling almost completely disappeared and I saw no difference in focus.

Take all that for what it's worth. A half-baked experiment in an effort to help. Hope it did.

Hey thanks for the feedback and the idea. Well I just tried it and I had the same result . Maybe it's supposed to have the beseler name towards the source image? Anyways, it almost creates a VERY SUBTLE pincushion effect turning it backwards, but it looks MUCH better so I'll keep it this way. It is a pretty lens, I found it on ebay, I'm using it with a 317mm field fresnel (surplus shed) and it throws a very nice, non-colored shifted image on my 10.6".

I also have the DIYPC 18" fatso, I don't need such a long throw and it has a yellowing lens in it that causes an annoying white shift. I'm very happy I switched to the 4"/14"FL beseler, I think it's a good find for a 10.6" build.

Indeed I agree. And I'm about to jump on the 10.6 bandwagon myself. Only I've been swapping the 14"/355mm FL Beseller and my 342mm triplet from a 3M OHP all night (my front fresnel is ~ 380mm, my panel 9") and I can't seem to decide which projection I like better. Visual memory seems about on par with aural (meaning very, very short) so I can't be certain, but I think the Beseller is a bit brighter but the OHP triplet is sharper and with better contrast.