| AI-S | A variant of AI designed to be used with Program and Shutter-priority exposure modes (1982). Manual focus lens. Distinguished by smallest aperture being printed in orange and a small scoop on the bayonet flange, which transmits aperture info. Otherwise same as AI |
| ED | Extra Low Dispersion Glass. Enable the production of lenses that offer superior sharpness and color correction by minimizing chromatic aberration. |
| IF | Internal Focusing |
| MF | Manual Focus |
| N | Originally, the actual designation used for the first AI lenses; beginning in 2005 it now stands for Nano Crystal Coat, a special type of flare reduction coating applied to newer lenses. |