As you can obviously see, there's a weird ring of light and hotspotting on dark image. My setup is a 8" HAMI 250W MH with spherical reflector and a precondenser lens.

help please. i tried varying the distances between reflector-lamp-precondenser and the collimator fresnel, and the ring doesnt seem to disappear. and it's really weird that circle is only outlined (thus a ring ) instead of it being filled.

Click to view attachment

Looks to me like a problem with the reflector or precondensor. See what happens if you remove the reflector. If the ring doesnt go away I blame the precondensor, which is non-"lumenlab standard"

LOL @ non-lumenlab standard

nways, i did try to remove not only the reflector but also the precondenser. The ring is still quite visible, not as much as before tho, but still, where does it come from? The fresnels? hehe

Look for light leaks around the triplet/focussing mechanism. I have a similar problem with my projector (but horizontal lines). I discovered it was due to light leaking from the front of my focussing mechanism...

Also check the fresnel - lcd - fresnel distances and whether your fresnels are the right way round. Remember the grooves should always face the LCD.

I have a similar issue due to cleaning my fresnels with 91% alchohol after getting a tiny bit of silicon on one of them. Good luck!