Manual focus this one before they went AF. Excellent optically, but a nightmare for handling compared to the Canon FD 500mm F/4.5L. Its shorter than the Canon 500mm, but has a larger diameter front element and there in lies the problem. Makes it very front heavy and is awkward to hold, makes hand holding tiresome compared to the Canon. Used now and again just to keep it shooting, but the Canon's handling leaves this lens for dead. Its a good spare for my favourite focal length. A few shots of White faced Heron's with the lens. All the best folks. Danny.