Received today, it's very compact and light weight.
Just plugged it into my DBK 21AF04, the field of view is really fast. Focus adjustment is not very good, but it works. Zooming can be done similarly.
There's a lock screw for focal length and focus, a nice touch.
At the widest setting, barrel distortion is quite apparently but it's expected for such a wide field of view at 2.3mm only! It should be nice as a finder lens, and for capturing milkway shots.
The next lens will be a Cosmicar 6mm f/1.2 prime lens which should be free of distortion, but it's not as wide as well. Should be good for more serious work.
Really want to try it out under stars.
I also tried it in my DMK 31AF03 on the next day, the field of view is even wider, and it gives slight fisheye view which is lovely, too!