Hey guys. What I have is a 7.5"x5.5" 4:3 screen size coming from a Pro lens set. I am getting great focus around the middle of the screen, but all 4 corners are fuzzy. Without changing out my football bulb for something with a smaller arc, what are the other things I can check to make sure they are aligned correctly.

I feel pretty good that the center of each lens is lined up with the axis of a line perpendicular to my lamps arc. When I put a piece of paper just before the triplet, I get a light image that is centered on the triplet.

What else can I check, adjust to get those corners in focus?

That's a pretty tiny image. Kinda defeats the purpose of a projector, don'it?

Anyway, are your fresnels bowed? Mine are, that might change the way they focus light toward the edges. I don't know for sure, just throwing out ideas.

Have you read Elken's Pro Triplet modification thread?

you are using the pro triplet? are your fresnels bowed at all?

The collimating fresnel is bowed a little bit, but I have it in a frame with the lexan, and I have used some pieces to make it lay flat. The front fresnel might be bowed a little at one corner, but the top edge is screwed into a rod, so it can't be the case for all 4.

Yes, I read the lens mod thread. Gave me constipation just reading it. brrrrrr I am not at the point I want to take that thing apart yet. lol

Interesting possible solution.

I cut out a circle in a piece of cardboard slightly smaller than the opening of the pro triplet. I placed that in front of the triplet on the fresnel side. I got pretty good improvements in the corner focus. See my PLOG for details and screenshots.

Pirin figured it out for me. I had the triplet backwards.

doh.

Glad it was that simple.

You're not the first and probably not the last to do that. It really looks like the flange should go on the outside.

It's actually very easy to mod the triplet. More or less you just unscrew the retaining ring, dump the lenses out (and mark them so that you can put them back in correctly), take the big spacer and put in a home-made small spacer, put the lenses back into the housing, put the big spacer in, and screw the retaining ring back in.

It definately seems like something that after you did it, like, twice you'd have it mastered.

Since I did mine I can see lots and lots of dust inside the triplet, I doubt it effects the projection at all, but it kinda looks bad. I'd suggest wearing gloves while doing the mod as well, if you decide to of course.

If your design dictates that the flange be on the outside you could always put the lenses in backward on-purpose.

so with the triplet right way around does the "iris" still help any with the image quality?

Good question! I will have to try that, though honestly it is razor sharp now.