Focal plane shutter SLR with coupled exposure meter
Around 1962, the camera manufacturers started to incorporate an exposure meter into the focal plane shutter SLR.
The first built-in exposure meters using selenium photocells were soon replaced by highly sensitive CdS (cadmium sulfide) cells.
Although most competing products featured what were called "built-in coupled exposure meter", only shutter speed was coupled and thus the photographer had to set aperture value after reading the indicator.
At this point, Nippon Kogaku K. K. had a great advantage compared to the competition.
When the Nikon F was released, every interchangeable Nikkor-Auto lens had an aperture-coupling claw, known as the "crab claws", and thus enabling to transfer the aperture value information to the exposure meter.
Taking this advantage, the Nikon F's "Photomic finder", in fact, featured a "full coupled" built-in exposure meter.
Those who used the Nikon F could gain the benefit of this new feature upgrade simply by buying the newest Photomic viewfinder as a replacement finder. However, since all new functions were incorporated into the Photomic finder, the camera body seemed to be a little bit unbalanced.
Like other manufacturers' cameras, the exposure meter should have
been provided in the body top cover for smart camera body.
On the other hand, lens shutter SLR cameras with quick-return mirror and automatic exposure mechanism, like the Nikon AUTO 35 (see previous issue Vol. 4.) were losing their raison d'etre.
The need for an impressive standard-class model to back up the Nikon F in a premium line of cameras gave rise to the Nikomat FT.