| Version | Serial no | Date | Screws | Engraving | Notes |
|---|---|---|---|---|---|
| Ai | 450001 < 450017 – 453940 > | 1977 - | 5+ | LMIJ | Thick rear protector, long projection from max aperture post prevents it fitting TC-16. |
| Ai | < 453953 – 454838 > | - | 5+ | MIJ | Thin rear protector, long projection from max aperture post. |
| Ai | 540021 < 540039 – 545201 > | - | 5+ | MIJ | New serial number from TC-16 manual. Short extension from the max aperture post, otherwise identical to earlier types. |
| Ai | < 543786 – 565127 > | - Nov81 | 3+ | MIJ | Now with three screws in lens mount. |
