Mounting up
One hole, over half a decade – why Nikon’s F-mount has stood the test of time
It’s not quite lens nirvana – there are some limitations to take into account
The F-mount celebrated its 50th anniversary in 2009, making it the longest-running lens mount for 35mm SLR interchangeable lens cameras in the world. The F-mount was introduced on the Nikon F in 1959 and it’s been a constant throughout Nikon’s history, providing a substantial amount of backwards and forwards compatibility between lenses and cameras over the past five decades.
Nikon decided that it needed to provide a degree of future-proofing and enable the use of larger aperture lenses. The result? The F-mount diameter of 44mm.
But the F-mount hasn’t stayed frozen in time, and there have been some notable evolutions. For instance, 1977 saw the introduction of auto aperture indexing (Ai). Ai-type lenses enable the automatic setting of maximum aperture. In 1983, the F-mount had to accommodate both autofocus and the exchange of aperture information between the lens and camera using central processing units. Is it compatible ? Although you can physically attach F-mount lenses from the ’60s to the latest Nikon digital SLRs – and vice versa – it’s not quite interchangeable lens nirvana, as there are a number of caveats and limitations to take into account. For a kick-off, Nikon’s non-Ai lenses may need to be modified to prevent mechanical damage when they’re attached to later bodies. Although DSLRs can accept Ai lenses, only high-end bodies will meter through the lens. In addition, some digital SLRs don’t have a built-in focusing motor, so can only autofocus when a lens with a built-in motor – AF-S or AF-P – is attached. And then there’s Nikon’s range of G lenses, which lack an aperture ring and are intended to work with digital SLRs where the aperture is adjusted using the camera’s command dial. This is not an exhaustive list!
Most F-mount lenses are designed to project an image that covers a frame of 35mm film, or an FX imaging sensor, which has the same 36x24mm proportions. Nikon’s DX cameras have sensors that are 1.5x smaller – approximately 24x16mm – but they retain the same F-mount. This means you can happily use ‘full-frame’ lenses on DX bodies, albeit it with the image cropped. Nikon’s smaller DX lenses can also be fitted on FX bodies, with the camera automatically cropping the image frame to DX size.