| Version | Serial no | Date | Screws | Engraving | Notes
|
|---|
| Ai | 920001 < 920131 – 930610 > | 1977 - | 5+ | LMIJ | Thick rear protector, long projection from max aperture post prevents it fitting TC-16.
|
| Ai | 931001 < 931318 – 945542 > | - | 5+ | MIJ | Thin rear protector, no projection from max aperture post. Start serial number from TC-16 manual.
|
| Ai | < 939039 – 959393 > | - | 3+ | MIJ | Only three screws used in lens mount.
|
| Ai | 105001 < 110055 – 193558 > 193574 | - Aug81 | 3+ | MIJ | New serial number. Focus ring with squarer front edge, compared to sloping edge for previous versions (Ai 28/2.8 had similar change). Aperture coupling prong made of pressed sheet metal instead of solid metal.
|
