the lens aperture f-stop to control depth of field (focus) until the needle was centered between two pincer-like brackets. The needle array was duplicated in a window next the top-mounted film rewind crank to allow exposure control without looking through the viewfinder. The meter was turned on by pulling the film wind lever out to the standby ready position and turned off by pushing it back flush against the camera. This was very advanced in 1965 and proved to be remarkably long-lived. Nippon Kogaku used it for all versions of the Nikkormat FT with incremental improvements. The Nikon FM, FM2 and FM2N of the succeeding Nikon compact F-series SLRs used an improved viewfinder only, center-the-LED system until 2001. The FT's viewfinder also had a fixed focusing screen with Nippon Kogaku's then standard central 4 mm microprism focusing aid plus 12 mm matte focusing surface. The Nikkormat FT accepted all lenses with the Nikon F bayonet mount (introduced in 1959 on the Nikon F camera) and a "meter coupling shoe" (or prong, informally called "rabbit ears"). The FT had a mirror lockup allowing its use with some specialised lenses for which an auxiliary viewfinder was provided. The FT was Nippon Kogaku's first SLR with a built-in TTL light meter. As such, Nippon Kogaku could not find a way to automatically synchronize their Nikkor Auto lenses' aperture information with the FT body. Therefore, mounting lenses required a special preparatory procedure. First, the lens' maximum aperture (smallest f-stop number) must be set against the film speed scale on the FT's shutter speed ring. Then, the "meter coupling pin" on the ring surrounding the FT's lens mount flange must pushed all the way to the right and the lens' aperture ring must be preset to f/5.6 to line up the "meter coupling shoe" with the pin for mounting. Note that the lens maximum aperture had to be reset every time the lens was changed. This was very inconvenient compared to some other SLRs of the 1960s. Note that modern AF Nikkor autofocusing lenses (introduced 1986) do not have a meter coupling shoe, but all non-G AF lenses have two pilot holes to retrofit the coupling shoe, making them 100% compatible with all Nikon F-mount cameras. Although most AF Nikkor lenses will mount and manually focus on the FT, the combination cannot provide open aperture metering; only stop down metering. Nikon's most recent 35 mm