K version
Ai version
Ai-S version
| Version | Serial no | Date | Screws | Engraving | Notes |
|---|---|---|---|---|---|
| K | 175021 < 175026 – 175056 > | Dec75 - Jun77 | 5+ | LMIJ | Accepts Ai kits 10 and 11. Some Ai lenses made with serial numbers in this range. |
| Ai | 175501 < 175506 – 175515 > | Jun77 - Mar82 | 5+ | LMIJ | Upgrade to Ai with no further changes. Serial numbers seen so far suggest only 15 made, but the actual numbers may be much higher. |
| Ai-S | 175901 < 175909 – 176202 > | Mar82 - 1998 | 5+ | MIJ | Upgrade to Ai-S with no further changes. |