Source 4 Bench Focus Issue

I've just finished cleaning a handful of our 26 and 36 degree units. I had to take the barrels apart to clean the lenses as there was a visible layer of residue on most of them. I did this one by one, following the instructions in the assembly manual. Now as I'm bench focusing them, I notice that I can see the lens pads in the beam image on many of them when I run the barrel in or out. I double checked several of them as I was focusing and made sure the lenses were are seated properly in the correct slots and facing the right direction. I compressed the lens cap all the way in before I started on each light, but I'm still seeing this aberration. I've added an image from a 36 degree fixture mid bench focus. You can just see the outline of the lens pads around the edge of the beam. Does anybody have any ideas or suggestions on how to fix it?

  • Start by bench focusing the lamp.  Your lamp is off center and has a hot beam.  That may help the other problem.  The original 36-degree lenses were difficult to focus.  If these are very old, that problem might be involved.

  • We have a similar issue, if not the same.

    We did some big maintenance / cleaning on the lights, since all shows have been cancelled due to the pandemic paranoia.

    All our 50º and 26º barrels are fine, half of the 36ºs are fine, half of them are screwed up. The only way to get rid of the issue is to pull out the end cap holding the lamp about 1 inch / 2-3cm, but that's -obviously - not a solution and losing a lot of output.

    It looks like there is a reflective bounce between the two lenses.

    The pictures below are of the "medium" bad one, we have two that are even worse.

    Any ideas?

    Half shadow in which we can see the lens pads:

    The extra "reflection" is really showing when using shutters:

    All is installed alike:

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