It gave out after a few minutes of testing, before I figured out the modes. Probably the electronic driver failed, but I am not sure it was not the led or connections. Maybe the driver could not take the rapid switching when I turned the tail cap. The treads are anodized but a bit rough.
Now I have replaced the led with a warm white T5 XM-L2, and the driver with a 7135 x 8. I smoothed the tail cap threads and wrapped a bit of paper around them to make it work as a twisty, replaced with duct tape. The tail button switch only momentarily interrupts to switch modes.
It does out throw my Raysoon TD-398 SK-98 clone with the same driver and its original T6, with a much smaller and moderately brighter spot, as expected from the first order optics. (The optics logic goes as follows: If you scale up the lens with the same focal length to diameter ratio, the throw increases because it catches the same amount of light but focuses it to a smaller sport. The Yezl has a longer focal length than that, which, in the limit of small diameter to focal length, does not change the throw but only makes the spot smaller.) Flood is right about the same.
I have a thicker lens of the right diameter, but it is too thick at the edge for the bezel to hold it on. As expected, it gives similar throw with a larger spot, on the ceiling because the bezel does not hold it in place. If I had a lathe, I could extend the step back farther into the moving head to make room for the thicker outer edge of the lens.
I was not able to find a short focal length Fresnel lens of near the right size. Apparently stage lighting is the only thing they are used for, and those are too big. Based on my earlier tests, that would be the ideal solution.
I still love the shape and most of the workmanship. I feel I have made enough pottery and jewelery to know a nice shape when I feel and see it. Fins would be silly on a light with such a big head. I ordered a UniqueFire UF-T20, which according to Any info about UniqueFire UF-T20?, performs better, but from the pictures it looks ugly. Maybe I can cannibalise its lens.
TangsFire C8, Yezl T9 with XM-L2 and 7135 x 8, Raysoon TD-398 with 7135 x 8.
