This ring seems to be the best that I have tested. But unlike the ring for FD to Micro 4/3 (GH4) on EF as the 7D c is a disaster. The lens that provides access to infinite FD rings makes blurry images ... A bit like the old soap opera "Dallas" "The Young and the Restless" ... Very sad. FD J have a superb collection that will be usable only in micro 4/3.