This is a great adapter that allows me to use a Canon FD 50/1.4 lens with my Sony a7s. Use the mechanism of your Canon FD lens to attach the lens to the adapter and make sure that the aperture/diaphragm control pin lines up appropriately with the mechanism for adjusting it on this adapter (it will feel like it has the correct "click" in when you do that and will easily mount).Once attached and placed on your camera, this adapter along with the Canon FD aperture open/closed feature allow you to focus wide open and then immediately close down to your desired f-stop using the "Lock <==> Open" ring on the adapter. That is a fantastic option to have for a manual focus lens and really assists with precisely positioning the focus point and with focusing in low light if you want to shoot stopped down. This feature alone, which I believe is unique to FD mount lenses, is a good reason to give preference to using FD lenses with the Sony a7 series. (My 35-70 zoom, however, is right now a Minolta, but this feature makes me think about using Canons also excellent 35-70 FD zoom).My first copy of this did have a significant amount of "play/wiggle" and eventually came undone. I should have contacted the seller (HiShop) immediately. I ended up contacting them via the "question about return" policy option *after* the return period had expired. They graciously replaced my adapter with a new one that works great and has no wiggle. I am very pleased with the product.