Canon introduced the EF mount in 1987, and it brought with it a number of innovations while ushering in the autofocus era for the company. Before that, though, was the FD mount, and while it had almost exclusively manual focus lenses, one special lens, the FD 35-70mm f/4 AF, actually had a very strange and unique autofocus system, and this neat video shows what it was like to shoot with.