We take ridiculously powerful autofocus that can lock onto something like a subject's eye and track it through a challenging environment for granted nowadays, and we sometimes forget that there was a time when autofocus did not even exist. However, in the late 1970s, autofocus began to appear, and even though Canon's lens mount at the time did not support it, they found a way to put it in a lens anyway. This neat video review takes a look at that lens.