The Topcon R is a 35mm SLR from Tōkyō Kōgaku which appeared in 1958. It is notable as an early Japanese SLR incorporating an instant-return mirror (following on from the Asahiflex). In addition to adopting the Exakta lens mount, it follows in offering a pentaprism which is detachable and exchangeable with a waist-level viewfinder hood. Likewise, the supplied 58mm f/1.8 Auto-Topcor uses a pressure activated diaphragm but with semi-automatic action (it is manually reopened with a lever atop the lens). Alternately the purchaser could choose an Auto-Topcor 35mm f/2.8 at the same cost.
Enlarger-manufacturer Beseler also began offering this camera under its own badging as the Beseler B Topcon.
The Topcon R manual and Beseler B Topcon manual are posted at Mike Butkus's OrphanCameras.com