Bronica's short-tele portrait lens — the leaf-shutter Zenzanon-MC 105mm f/3.5 for the ETR.
The Bronica Zenzanon-MC 105mm f/3.5 is a short-telephoto lens for the Bronica ETR 6x4.5 medium-format system. The MC label denotes the multi-coated first-generation Zenzanon optics supplied with the early ETR bodies, before the PE line replaced them. On the 645 format a 105mm falls into the classic short-tele range used for portraits and general work.
This manual-focus lens mounts on the Bronica ETR leaf-shutter bayonet and offers a focal length of 105mm with a maximum aperture of f/3.5. It uses the in-lens Seiko leaf shutter common to the ETR system, giving flash synchronisation across the full shutter-speed range. Element counts, weight and filter size are left out here because they cannot be confirmed from the sources at hand.
A 105mm on 6x4.5 gives a flattering perspective for head-and-shoulders portraits and a comfortable working distance from the subject. The moderately long focal length compresses the background gently and, combined with the larger negative, renders smooth out-of-focus areas. It also serves for detail shots and tighter general framing where a normal lens is too wide.
On the used market the MC 105mm is a common and affordable ETR lens. Check the leaf shutter for even firing at all speeds and listen for sluggish slow speeds that point to old lubricant. Inspect the elements for haze, fungus and separation, confirm the aperture blades are dry and snappy, and verify the coupling to the body and back works correctly.