Bronica's wide-angle 645 prime — the leaf-shutter Zenzanon-MC 40mm f/4 for the ETR system.
The Bronica Zenzanon-MC 40mm f/4 is a wide-angle lens for the Bronica ETR system, the 6x4.5 medium-format SLR line launched in the mid-1970s. The MC designation marks the earlier multi-coated generation of Zenzanon glass that shipped with the original ETR body before the later PE optics arrived. Sitting at the wide end of the ETR range, it was intended for photographers who needed a broad angle of view on the 645 frame.
This is a manual-focus lens for the Bronica ETR leaf-shutter mount, with a focal length of 40mm and a maximum aperture of f/4. On the 6x4.5 format its coverage is roughly comparable to a moderate wide angle on smaller formats. It carries the in-lens Seiko leaf shutter used across the ETR system, which allows flash synchronisation at all shutter speeds. Other construction figures are omitted here rather than stated without confirmation.
As a wide-angle optic on a medium-format body, the 40mm suits landscape, architecture and interior work where a broad field of view and the tonal smoothness of the larger negative are wanted. Stopping down brings depth of field across the frame, which is helpful for scenic and building subjects. The leaf shutter and flash sync at all speeds also make it usable for fill-flash outdoors.
On the used market these MC-generation lenses turn up less often than the later PE versions and are typically priced below them. When buying, check the leaf shutter fires evenly at slow and fast speeds, look for haze, fungus and separation in the glass, and confirm the aperture and shutter actuate cleanly. Inspect the mount and check that the coupling to the ETR body and film back is intact.