No one asked this question, but I checked my 180mm f/2 APO-Summicron-R, and it has a slight ninja (blue-belt, say) aperture from f/2.4-f/3.6, with f/3.6 being very, very slight, and the worst point being only about half as pronounced as the photo above. Interestingly, depending on where you look from, you can also see slight assymmetricality of the aperture wide open, with a little ninja on one side only. If you place your eye where the film/sensor would be, you cannot see this, however, and the opening is perfectly round. The serial number start with 3740.