I've only had my M5 for a few days and have been using the kit lens while waiting for my 22mm f/2 to arrive. Today I tried the EF to EF-M Adapter with two lenses -- the old 50mm f/1.8 II and the 40mm f/2.8 Pancake. Drove me absolutely crazy with the incessant searching as I moved about with the camera. The 50 1.8 II was particularly clunky and just wouldn't shut up. I was expecting it to have a full-blown nervous breakdown. I did not notice anything similar with the 15-45 kit lens. So I called both B&H and Canon thinking something was wrong with the Adapter and was told that that is normal behavior with the Continuous AF turned on. Makes sense. So I turned it off and voila! All is well.