Black metal body. Green 'AE' markings. Rectangular locking button. Plastic focus grip. This is newest version of the 21mm, spotted by its smaller (f/22) minimum aperture and its larger (f/2.8) maximum aperture. Konica's own 21mm lens had a max aperture of f/4 and a 77mm filter. This version is much smaller & lighter, managing to retain the 55mm Konica trademark filter thread. The specific lens used in this test was manufactured in May of 1979 (code: 9S).
1979 - 84
Hexanon - E
f/2.8 - 22
This lens isn't as sharp in the corners as the older Konica f/4 version, but it's not bad either. The same is also true for it's infrared performance. It may not be the best performing IR lens in the Konica range, but it's not quite at the bottom of the pack either and that still puts it in pretty good standing. The below samples were not cherry picked to avoid any hotspots, so hopefully this reflects the typical contrast and quality that you could expect from random image taking.