I found a solution to rechipping my old Sigma Canon mount lenses, so they work with my newer Canon 60D, 80D body. Works with all Sigma lens models. I just did two Sigma 70-210 and a Sigma 400mm lens. Easy to install and great instructions. Many people said not possible? haha Works like a charm! www.facebook.com/rechip. You can purchase here and all the info you need is there also. Very Cheap.