had been looking for an adapter for my old Praktikar lens for a long time, but either there was nothing on the market or the products had lousy reviews that made me worried about the lens. The shipping came from overseas and was estimated with significantly longer waiting time than it was in the end. The adapter was there within a week. It was packaged well and appears to be of good quality. I immediately put the adapter on my lens (a 50mm 1.8 Carl Zeiss Jena). When I put it on, I had to apply some pressure to push the leaf spring down. The lens then snapped into place reliably and could be placed on the body without any problems. It was also easy to remove, so that the lens can now be carried in the backpack as standard and I can use the slightly different bokeh for gimmicks :) UPDATE: From a purely mechanical point of view, a corresponding lens can be attached to the Canon 5D Mark 3 with the adapter, but the Spiegel offends, so that there is an error message in the body. Whether this applies to full format in general or whether it depends on the lens, I cannot say due to the lack of test objects. In any case, the adapter for my Carl Zeiss Jena 50mm 1.8 does not work on the 5DMIII... Too bad.