I've had the Techart EF to NEX adapter now for about a month. Some of the lenses that I've tried are Canon EFS 10-22, EF 70-300, Tamron 90mm macro (about 20 years old), Sigma 150-500. The best adapted lens is the 10-22. Its focus is reasonably fast and accurate. Sometimes but not often I have had the aperture not close so taking a few shots and checking the images is necessary. The focusing on the 70-300 is kind of slow. The focus on the Tamron 90mm is slow and is rarely accurate. Since I use this as a macro lens I'm not in a rush and manual focus is preferred anyways. The focus on the Sigma 150-500 is too slow for what I was shooting - flying swans. The image peaking feature is helpful but not quite as good as using my Canons for fast action shots. It has Image Stabilization but I haven't really tested that function yet. EXIF data often is written accurately too. So far I'm more than satisfied with the adapter.