A small line of professional super telephoto lenses designed for Nikon 35mm film SLR cameras with Nikon F mount. These were the first Nikkor lenses to have a D/C coreless focus drive motor built into the lens rather than the body which enabled faster autofocusing.
The AF-I lenses offer a number of very convenient additional features: the M/A mode that permits manual override of the autofocus operation at any time, a focus range limiter to eliminate unnecessary lens movement, and four AF-lock buttons situated around the front end of their barrels to improve their handling.
An important feature of the AF-I type is that they do not require any electrical power to be operated manually and can therefore be used on non-AF camera bodies.