The AI vs. AI-S distinction
The Ai-type Nikkor lens was introduced in 1977 and was the first major change to the Nikon F mount since it launched in 1959. The name stands for Automatic Aperture Indexing — the AI standard adds a Meter Coupling Ridge to the aperture ring, which encodes the current aperture setting relative to the maximum, and a Lens Speed Indexing Post on the mounting flange, which encodes the maximum aperture itself. Before this, you had to manually “pre-set” the lens by twisting the aperture ring through its full range before shooting — the AI system did that automatically. You could now mount a lens and start shooting with proper metering immediately. Grays of WestminsterWikipedia
In 1981, Nikon improved the AI system to AI-S. The big difference is that the relationship between how much the camera moves the little lever that closes the aperture and how far the aperture closes is now standardized. In practical terms, this meant the camera body could control the aperture predictably — essential for shutter-priority and program auto-exposure modes. Digital Photography Review
The specific additions on AI-S lenses were:
- A Lens Type Signal notch (the “scoop”) — a small semi-circular cutout in the rear bayonet, the quickest visual identifier
- Standardized linear aperture movement — the stop-down lever moves the aperture in a predictable, linear way
- A Focal Length Indexing Ridge on lenses 135mm and longer, for high-speed program mode
- The smallest aperture value printed in orange on both aperture scales
The only two camera models that actually make full use of the AI-S lens mount are the Nikon FA and F-501. All other Nikon cameras make no differentiation between the AI and AI-S mount. So for most shooting purposes, the practical difference is minimal — AI-S matters mainly if you owned an FA or were doing matrix-metered program/shutter-priority work. Grays of Westminster
Optically, the two generations are largely the same. The optical construction of most AI lenses is either identical or very similar to the equivalent AI-S variants, and they operate with the same functionality on compatible Nikon camera bodies. Grays of West
Nikon AI Nikkor Prime Lenses (1977–1981)
Sorted wide to narrow. Lenses originating before 1977 were updated to AI specification that year.
| Focal Length | Max Aperture | Approx. AOV (diagonal) | Type | Years Produced |
|---|---|---|---|---|
| 6mm f/2.8 | f/2.8 | 220° (circular fisheye) | Fisheye | 1972–1997 (AI from 1977) |
| 7.5mm f/5.6 | f/5.6 | 180° (circular fisheye) | Fisheye | 1965–1984 (AI from 1977) |
| 8mm f/2.8 | f/2.8 | 180° (full-frame fisheye) | Fisheye | 1970–1983 (AI from 1977) |
| 13mm f/5.6 | f/5.6 | 118° | Ultra-wide rectilinear | 1977–1982 |
| 15mm f/3.5 | f/3.5 | 110° | Ultra-wide | 1973–1984 (AI from 1977) |
| 16mm f/3.5 | f/3.5 | 170° (full-frame fisheye) | Fisheye | 1974–1984 (AI from 1977) |
| 18mm f/3.5 | f/3.5 | 100° | Ultra-wide | 1975–1981 (AI from 1977) |
| 20mm f/3.5 | f/3.5 | 94° | Ultra-wide | 1977–1984 |
| 20mm f/4 | f/4 | 94° | Ultra-wide | 1974–1977 |
| 24mm f/2 | f/2 | 84° | Wide-angle | 1977–1981 |
| 24mm f/2.8 | f/2.8 | 84° | Wide-angle | 1967–1984 (AI from 1977) |
| 28mm f/2 | f/2 | 74° | Wide-angle | 1971–1981 (AI from 1977) |
| 28mm f/2.8 | f/2.8 | 74° | Wide-angle | 1974–1981 (AI from 1977) |
| 28mm f/3.5 | f/3.5 | 74° | Wide-angle | 1961–1981 (AI from 1977) |
| 35mm f/1.4 | f/1.4 | 62° | Wide-angle | 1970–1981 (AI from 1977) |
| 35mm f/2 | f/2 | 62° | Wide-angle | 1965–1981 (AI from 1977) |
| 35mm f/2.8 | f/2.8 | 62° | Wide-angle | 1959–1981 (AI from 1977) |
| 45mm f/2.8 GN | f/2.8 | 51° | Guide Number (flash) | 1966–1984 (AI from 1977) |
| 50mm f/1.2 | f/1.2 | 46° | Normal | 1978–1981 |
| 50mm f/1.4 | f/1.4 | 46° | Normal | 1962–1981 (AI from 1977) |
| 50mm f/1.8 | f/1.8 | 46° | Normal | 1978–1981 |
| 55mm f/1.2 | f/1.2 | 43° | Normal | 1965–1978 (AI from 1977) |
| 55mm f/2.8 Micro | f/2.8 | 43° | Macro | 1979–1981 |
| 55mm f/3.5 Micro | f/3.5 | 43° | Macro | 1961–1981 (AI from 1977) |
| 58mm f/1.2 Noct | f/1.2 | 40° | Normal / Aspherical | 1977–1981 |
| 85mm f/1.4 | f/1.4 | 28°30′ | Portrait telephoto | 1977–1981 |
| 85mm f/2 | f/2 | 28°30′ | Portrait telephoto | 1977–1981 |
| 100mm f/2.8 | f/2.8 | 24° | Short telephoto | 1977–1984 |
| 105mm f/1.8 | f/1.8 | 23°20′ | Portrait telephoto | 1977–1981 |
| 105mm f/2.5 | f/2.5 | 23°20′ | Portrait telephoto | 1959–1981 (AI from 1977) |
| 105mm f/4 Micro | f/4 | 23°20′ | Macro | 1970–1983 (AI from 1977) |
| 135mm f/2 | f/2 | 18° | Telephoto | 1977–1981 |
| 135mm f/2.8 | f/2.8 | 18° | Telephoto | 1965–1981 (AI from 1977) |
| 135mm f/3.5 | f/3.5 | 18° | Telephoto | 1959–1984 (AI from 1977) |
| 180mm f/2.8 ED-IF | f/2.8 | 13°40′ | Telephoto | 1977–1981 |
| 200mm f/2 ED-IF | f/2 | 12°20′ | Telephoto | 1977–1981 |
| 200mm f/4 | f/4 | 12°20′ | Telephoto | 1961–1981 (AI from 1977) |
| 200mm f/4 Micro IF | f/4 | 12°20′ | Macro | 1978–1981 |
| 300mm f/2.8 ED-IF | f/2.8 | 8°10′ | Super-telephoto | 1977–1981 |
| 300mm f/4.5 ED-IF | f/4.5 | 8°10′ | Super-telephoto | 1977–1981 |
| 300mm f/4.5 | f/4.5 | 8°10′ | Super-telephoto | 1962–1981 (AI from 1977) |
| 400mm f/3.5 ED-IF | f/3.5 | 6°10′ | Super-telephoto | 1977–1981 |
| 400mm f/5.6 ED-IF | f/5.6 | 6°10′ | Super-telephoto | 1977–1981 |
| 500mm f/5 Reflex | f/5 | 5° | Mirror lens | 1963–1984 (AI from 1977) |
| 500mm f/8 Reflex | f/8 | 5° | Mirror lens | 1977–1981 |
| 600mm f/5.6 ED-IF | f/5.6 | 4°10′ | Super-telephoto | 1977–1981 |
| 800mm f/8 ED-IF | f/8 | 3°10′ | Super-telephoto | 1977–1981 |
| 1000mm f/6.3 Reflex | f/6.3 | 2°30′ | Mirror lens | 1959–1984 (AI from 1977) |
| 1200mm f/11 ED-IF | f/11 | 2° | Super-telephoto | 1977–1981 |
| 2000mm f/11 Reflex | f/11 | 1°10′ | Mirror lens | 1970–1984 (AI from 1977) |
Nikon AI-S Nikkor Prime Lenses (1981–present)
Sorted wide to narrow. Several lenses remain in Nikon’s current catalog as of 2024.
| Focal Length | Max Aperture | Approx. AOV (diagonal) | Type | Years Produced |
|---|---|---|---|---|
| 6mm f/2.8 | f/2.8 | 220° (circular fisheye) | Fisheye | 1981–1997 |
| 8mm f/2.8 | f/2.8 | 180° (full-frame fisheye) | Fisheye | 1981–2000 |
| 13mm f/5.6 | f/5.6 | 118° | Ultra-wide rectilinear | 1982–1998 |
| 15mm f/3.5 | f/3.5 | 110° | Ultra-wide | 1981–2000 |
| 16mm f/2.8 | f/2.8 | 170° (full-frame fisheye) | Fisheye | 1981–present |
| 18mm f/3.5 | f/3.5 | 100° | Ultra-wide | 1981–1989 |
| 20mm f/2.8 | f/2.8 | 94° | Ultra-wide | 1984–present |
| 24mm f/2 | f/2 | 84° | Wide-angle | 1981–2006 |
| 24mm f/2.8 | f/2.8 | 84° | Wide-angle | 1981–2006 |
| 28mm f/2 | f/2 | 74° | Wide-angle | 1981–2005 |
| 28mm f/2.8 | f/2.8 | 74° | Wide-angle | 1981–2006 |
| 35mm f/1.4 | f/1.4 | 62° | Wide-angle | 1981–2006 |
| 35mm f/2 | f/2 | 62° | Wide-angle | 1981–2006 |
| 45mm f/2.8 GN | f/2.8 | 51° | Guide Number (flash) | 1981–1989 |
| 50mm f/1.2 | f/1.2 | 46° | Normal | 1981–present |
| 50mm f/1.4 | f/1.4 | 46° | Normal | 1981–present |
| 50mm f/1.8 | f/1.8 | 46° | Normal | 1981–present |
| 55mm f/2.8 Micro | f/2.8 | 43° | Macro | 1981–present |
| 58mm f/1.2 Noct | f/1.2 | 40° | Normal / Aspherical | 1981–1997 |
| 85mm f/1.4 | f/1.4 | 28°30′ | Portrait telephoto | 1981–2006 |
| 85mm f/2 | f/2 | 28°30′ | Portrait telephoto | 1981–2005 |
| 105mm f/1.8 | f/1.8 | 23°20′ | Portrait telephoto | 1981–2005 |
| 105mm f/2.5 | f/2.5 | 23°20′ | Portrait telephoto | 1981–2005 |
| 105mm f/2.8 Micro | f/2.8 | 23°20′ | Macro | 1983–present |
| 135mm f/2 | f/2 | 18° | Telephoto | 1981–2005 |
| 135mm f/2.8 | f/2.8 | 18° | Telephoto | 1981–2006 |
| 180mm f/2.8 ED-IF | f/2.8 | 13°40′ | Telephoto | 1981–2006 |
| 200mm f/2 ED-IF | f/2 | 12°20′ | Telephoto | 1981–2006 |
| 200mm f/4 Micro IF | f/4 | 12°20′ | Macro | 1981–1993 |
| 300mm f/2 ED-IF | f/2 | 8°10′ | Super-telephoto | 1982–2006 |
| 300mm f/2.8 ED-IF | f/2.8 | 8°10′ | Super-telephoto | 1981–2006 |
| 300mm f/4.5 ED-IF | f/4.5 | 8°10′ | Super-telephoto | 1981–2005 |
| 400mm f/2.8 ED-IF | f/2.8 | 6°10′ | Super-telephoto | 1981–1998 |
| 400mm f/3.5 ED-IF | f/3.5 | 6°10′ | Super-telephoto | 1981–2001 |
| 400mm f/5.6 ED-IF | f/5.6 | 6°10′ | Super-telephoto | 1983–1998 |
| 500mm f/4 ED-IF | f/4 | 5° | Super-telephoto | 1981–2006 |
| 500mm f/8 Reflex | f/8 | 5° | Mirror lens | 1981–2001 |
| 600mm f/4 ED-IF | f/4 | 4°10′ | Super-telephoto | 1981–2006 |
| 800mm f/5.6 ED-IF | f/5.6 | 3°10′ | Super-telephoto | 1981–1998 |
| 1200mm f/11 ED-IF | f/11 | 2° | Super-telephoto | 1981–1997 |
| 2000mm f/11 Reflex | f/11 | 1°10′ | Mirror lens | 1981–2000 |
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