|Lens mount||Nikon F-mount|
|Focus||TTL Phase Detection Autofocus (1 zone)|
|Frame rate||2.5 frame/s|
The Nikon F-501 (sold in North America as the N2020) was the first successful autofocus SLR camera sold by the Nikon Corporation beginning in 1986. A nearly identical, albeit manual focus version, called the Nikon F-301 (N2000 in North America) was also available. Subsequent models in the consumer line included the Nikon F-401, Nikon F-601, and Nikon F-801 / F-801S.
The F-501 is a 35 mm single-lens reflex camera with automatic film loading and advance, almost a first for Nikon (the F-301 was their first SLR to feature this). The built-in motor drive provided single (one exposure and frame advance per shutter button press) or continuous (shutter will fire and film will advance so long as the shutter button is depressed) modes. Maximum film advance speed was 2.5 frames per second (frame/s) on continuous mode, but could be as slow as 1.4 frames/s depending on the status of the focus/exposure locks. Rewind was accomplished manually by a familiar rewind knob which doubled as a release for the back. The F-501 was powered by four AAA batteries housed in the bottom of the camera body, although it could utilize AA sized batteries with an optional attachment (MB-3).
The F-501 used a through-the-lens (TTL) "passive" phase-detection autofocus method for establishing focus. Unlike active systems, which set approximate focus based on distance to the subject, the "passive" system utilizes a CCD to "see" the focus subject and focus in a manner similar to a human operator. This method is more precise than the active method, but requires more light to function. The F-501 had two focus modes available, single, in which focus was established and would not change so long as the operator held down lightly on the shutter button, and continuous, in which the lens would continuously re-focus on whatever was in the focus area.
The F-501 could be set for auto exposure, "hi-speed" auto exposure, "dual" auto-exposure (with Ai-S type lenses) which switches between regular auto exposure and hi-speed autoexposure based on the lens attached, aperture priority, or full manual exposure modes, which would allow the user to set both the aperture and shutter speeds. The shutter speed and auto-exposure modes were set the by use of a dial on the top of the camera, while the aperture ring on the lens was used for aperture control. The "hi-speed" auto-exposure would tend to favor higher shutter speeds and wider aperture settings than the "normal" auto exposure mode, while the "dual" mode would offer "normal" auto-exposure with lenses at focal lengths less than 135 mm and "hi-speed" auto-exposure if a lens was longer than 135 mm.
The F-501 supports TTL flash exposures with a wide range of Nikon flashes. The Nikon SB-20 flash was especially designed for this camera.
Like all Nikon SLRs, the F-501 accepts Nikon's F-mount lenses, but will only autofocus with lenses designated "AF." Likewise, fully automatic exposure will only work with Ai-S type lenses, including many autofocus lenses (G-type lenses are not supported by the F-501). In both cases, the camera will function with lenses without these abilities, but will not autofocus or may not have full auto exposure capabilities. AF lenses designated "D" add no functionality to the F-501, and "AF-S" and "VR" lenses will not perform their special functions if attached to an F-501.
Continuing Nikon's practice at time, the F-501 had interchangeable focusing screens, a feature that is now quite unusual. Three screens (types B, E and J) were available for the F-501.
Breaking from practice, though, Nikon removed the ISO-type cable release socket. Remote control functionality is still available, however, through the three-pin terminal on the camera's front with the Remote Cord MC-12 and the like. ISO cable releases can be accepted by the Terminal Release MR-3, which also doubles as a second shutter button.
In design terms, the F-501 took a different look from previous Nikon cameras. The introduction of a polycarbonate-clad body rather than metal, which caused the camera to be black instead of silver, was the most immediate and obvious change. Also new to this model was the addition of an extended grip on the shutter button side of the camera body, a feature which has grown in subsequent autofocus SLR camera designs ever since. Nikon adopted some design concepts from the F501 in the company's first professional autofocus SLR, the Nikon F4, in 1988.
Less obvious is the addition of a red stripe on the right hand front side of the camera. The stripe first appeared in the Nikon F3 in 1980, and some variation of it has been a design feature of every Nikon autofocus camera since, but on the F-501 the stripe was horizontal rather than vertical for the first time.
Media related to Nikon F-501 at Wikimedia Commons