| Year | 1971 |
| Lens Groups | 6 |
| Lens Element | 8 |
| Aperature Blades | 8 |
| Minimum Aperture | f/16 |
| Closest Focusing | 0.6 m |
| Max. Magnifcation | 1:9.1 (0.11x) |
| Filter Size | 58 mm |
| Diameter x Length | 75.8 x 55 mm |
| Weight | 605 gr (1.33 lb) |
| Hood | BS-58 |
I chanced into this lens a couple years ago and in researching what I had learned what a rarity it is. This lens is touted by Canon as the first aspherical lens for an SLR. The aspherical glass in the lens is ground by hand as opposed to the later ASPH versions that had machine made elements. The lens is a beast- mount it on an F1 and you know you're carrying something, no nFD plastic fantastic here. It is also supposed to have thorium glass, which leads to yellowing over time. My sample has a bit of yellow, but nothing that interferes with performance, if fact on black and white film, it acts as a built in yellow filter and it renders color, especially color slides wonderfully. Wide open, it is sharp as can be in a narrow plane and the out of focus area is beautifully smooth. Stopped down, it remains sharp and colors seem to deepen.
Build quality is excellent; metal where it ought to be metal. The issue I have with build is that the paint had some sort of laquer on it which, when it wears off, doesn't look so great.
Most copies of this lens seem to have made their way to collections in Asia, so if you see one and think you want it, buy it, because chances are it won't be around for long.