Changing to the Fotodiox Tough E-mount is very nerve wracking, I gotta say. When I was prying open the plastic shim, I felt that that was the most dangerous part since you can easily slip and scratch the sensor. I did break the little bolt at the 3 o' clock position, but there is still one at the 9 o'clock on top of the four screws, and the Tough E-mount feels solid. The only thing I'm worried right now are two black, somewhat fuzzy dots on the left side and a smaller one on the bottom of the frame. I only see them from around f/16 and up, though. When I see the sensor, however, I don't see any physical marks at those locations, though =| What do you guys think it is?