Topcon, the camera brand of Tokyo Kogaku K.K., fitted the RE Auto Topcor 135mm f/4 to its RE Super and Super D SLR bodies from the 1960s, part of a lens lineup notable for pioneering through-the-lens metering coupled directly to the lens aperture.
The lens is a moderate telephoto prime built on Topcon's own auto-diaphragm bayonet, mechanically related to but not fully interchangeable with the Exakta mount used by Topcon's earlier R-series bodies. Construction is fully metal with a preset-free automatic diaphragm coupled to the camera's TTL metering system.
Optically the lens is a competent, moderately sharp performer for its era, with pleasant if unremarkable rendering typical of 1960s Japanese telephoto primes. It is valued today chiefly by Topcon system collectors seeking period-correct glass rather than for outright optical performance.
Complete, working examples are relatively scarce since Topcon's camera business wound down in the 1970s, and prices reflect collector demand within a small user base. Buyers should confirm the auto-diaphragm coupling still actuates correctly, since a seized mechanism is a common fault on unused examples.