I've already described in my AL-1 QF piece part of Canon's early response to AF in SLRs. It should be noted that Canon were one of the pioneers of AF in 35mm compacts - Polaroid had led the AF world with the sonar AF on an SX-70 model, and Minolta had produced the first 35mm compact with passive AF, but Canon produced the first one with what they termed "Solid State Triangulation". And this was the technology they used to produce their first AF SLR lens, the lens in question, in early 1981. It was based on the 35-70 f4, a very decent compact zoom for the time, but added a huge shell in a colour very familiar to us now from long L lenses - off white. It takes 2 AA batteries, and has a battery check button and LED, and a focus push button. Zoom is controlled by a lever, whilst the aperture ring is entirely conventional. This lens will mount and AF on ANY FD body. In use, the zoom lever works really well, rather to my surprise. The lens is huge, bulky and heavy, and looks odd because the bulge with the AF receptors sits at roughly at the 1.30 position when viewed from the front. It feels very weird on lighter bodies, but actually feels rather good on an F-1. So, to focus, you switch it on, and press the button. A beep indicates focus has been achieved - takes a little while, but isn't as slow as I had expected, and is also surprisingly effective, and the motor is reasonably quiet. My example has a slightly damaged battery compartment, and I have to hold it in to be sure it will focus, but that's not a big problem. Optical quality is rather good - by this time, relatively simple zooms generally were. All in all, it's not the most practical lens to use, but it's of interest in terms of the development of AF at Canon. Already with this lens and the AL-1 QF we see features that persist to this day - sensor in body, motor in lens - although much is, of course, very different. Several other manufacturers produced similar lenses, and indeed lenses with self-contained AF continued to be available throughout the 80s, even after the appearance of body-integral AF - the last one I can think of being the Sigma 55-200 AF that was also available in Praktica Bayonet branded as a Prakticar.