Dunno if the S2+ comes with different versions of the LED, but the one I had was pretty clean even with the come-with clear lens, but still made a very noticeable difference when I stuck the ZWB2 in there and transplanted it into a purple S2+ host.
My WK30 (original 395nm) shows lots of visible purple, which isn’t too bad.
My 365nm drop-in, also in a purple ’501 host, spilled quite a bit of bluish-white light but what a huge difference with a 26mm ZWB2 filter vs plain glass.
I definitely want/need a filter for the ’31, though. Think it’s that visible greenish light that gives eggs that eerie color.
Went to mail some letters latelatelate last night, took the ‘31 to just see what glows around the nabe. Surprisingly, not much, except for paper/plastic in peoples’ garbage bags that were out for pickup.
As a follow-up, I found and ordered the cheapest 19.5mm ZWB2 filter I could find at the time on AliExpress.
The lens was just a hair smaller in diameter than the original in the SP31 UV (making me think it was closer to 19mm than 19.5mm), but it still fit in the light without issue.
Before I swapped in the filter:
After I swapped in the filter:
And the Convoy S2 LG UV for comparison, with the same camera settings:
Ultimately, I think it does the trick. The visible greenish light is eliminated, and the intensity of the fluorescence from the UV light is not noticeably reduced.
It’s also easier to do an apples-to-apples comparison of the Convoy and the Sofirn. With the visible light gone, it appears that the peak intensity of the Sofirn is a bit less than that of the Convoy.
The original clear lens on my SP31UV is 1.5 mm thick. This ZWB2 filter lens is 2.0 mm thick.
Did the extra thickness cause any issues with screwing down the bezel all the way onto the body until it bottomed out (as it came from the factory) or to avoid crushing anything, did you need to leave a ~0.5 mm gap between the bezel and the body due to the extra thickness of the filter?
I wonder how much different filter thicknesses affect the beams peak intensity since they are available in 1.0 to 3.0 mm thicknesses. All the 1.5 mm thick ZWB2 filters I could find where either too small in diameter or slightly too large in diameter and would need to be re-worked to fit (which I could do by hand-grinding on a diamond sharpening stone but would prefer not to).
Good point! I took some comparison photos to show the difference.
With the thicker lens, you can also consider removing the atypical plastic ring in the bezel to slightly reduce the gap:
Note that in any configuration, the bezel still goes fully over top of the O-ring on the body, so it’s really within the margin of error and doesn’t compromise waterproofing.
With the ring removed, the gap is basically comparable to other Sofirn lights with a similar design:
