I had to spend at least an hour (and many ennervement) with the camera on tripod, lens mounted and locked to infinity, in an attempt to stall the adjustable part of this ring ... the problem is when I found the right timing and I screwed back each screw, it's almost impossible to keep the parallel objective to the sensor because it takes tighten every little screw has small, otherwise it will decale one side!
must maintain otic same time, keep an eye on the screen to verify that the item is always good .... I honestly thought I was going to give up. and then a miracle, I think I succeeded, finally, so I well tightens the 3 screws .... gradually to realize that by doing this the whole it is still slightly decallé (back) .... if you want to reach hysterics, well I recommend this adapter, it's perfect for that!
Same problem with the ring Nikon / Nex from the same supplier / vendor (XCSOURCE), by which it is not adjustable against. Unacceptable!