ASAHI PENTAX SPF
Improved successor of PENTAX SP. Metering can be done with full open aperture. Hot shoe with X-terminal was added.
For full aperture metering function, information of aperture ring location angle have to be transmitted from lens to body. It is easy to realize this function for bayonet mount cameras, but it is not for screw mount camera. This is because there have to be some diversion of angle of lens fitting location in case of screw mount.
When you rotate lens to fit it on screw mount of SPF body, you can notice by feeling with your hand that mechanical transmission mechanism inside the camera body successfully links with the lens aperture ring at last one rotation of the lens.
New K-series was released two years later from the release of this camera. Both of K-series and S-series including SPF were sold in parallel for a while, but S-series was completely replaced by K-series finally.
PENTAX K1000 is the K-mount version of this camera.
Same function and usage as SPF was inherited continuously for more than 20 years.
This camera has favorable combination of full aperture metering and legacy of Pentax SP functionality with needle centering meter etc.
In addition, the smoothness of rotation and click-stop feeling of 55mm/f1.8's aperture ring are most excellent level.
I would like to say this camera has most basic feature in the quality of operation,
Mechanical shutter, manual metering.
Start of sales : 1973
Weight: Body:656g + 55mmf1.8:205g =861g