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| Used Cameras » 35mm » Pentax SM |
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| Asahi Joint Stock Company, founded just after the First World War, was the ultimate antecedent of the modern Pentax Corporation. It had its roots as an optical supply house fabricating such optical devices as binoculars and supplying lenses for amateur cameras to the corporate precedents of Minolta (Chiyoda Kōgaku Seikō) and Konica (Konishiroku). The first Asahiflex, the Asihiflex I, was produced until 1953 and had speeds from 1/25th to 1/500th but no instant return mirror and no pentaprism image inverter. The lack of an instant return mirror and pentaprism rendered this combination of technological wonders little more than a niche curiosity since between the consequent blackout and non intuitive image inversion; rangefinders were very arguably much easier to use. The early Asihiflexes had an incompatible, with the later M42 screw mount, M37 mount and are distinguishable in its characteristically unlabeled models as follows: Asahiflex I (1952) lacks slow speed dial, lacks instant-return mirror and has only one proprietary sync socket. Asahiflex IA (1953) lacks slow speed dial, lacks instant-return mirror and has two proprietary sync sockets. Asahiflex IIB (1954) lacks a slow speed dial, has an instant-return mirror and has two standard sync sockets. Asahiflex IIA (1955) has a slow speed dial and an instant-return mirror. 42mm Screw Mount that became an early industry standard that was the mount first employed first in 1957 introduced with the Pentax AP and S (which differed only in its shutter speed sequence). The 42mm SM mount reigned in the Pentax line until 1975 when Pentax introduced it K mount bayonet mount. |
