I just got the protama 0.6x wide angle adapter for nex. Most people get it to turn their 16mm into a 9,6mm (14,4mm EQV), but I´m going to test it this weekend with the SLR Magic 23mm f1.7 (49mm filter thread), getting a 13,6mm f1.7 (20,7mm).
My first impression of the Protama is that it´s big but it´s very very light. I put it quickly on the 16mm and it could focus perfectly with no stress. With some distortion correction it could be really fun to use.
Anyway, I´ll try to post some tests this weekend.