Mamiya's short-normal 645 prime — the manual-focus Sekor C 70mm f/2.8 for medium format.
The Mamiya Sekor C 70mm f/2.8 is a short-normal lens for the Mamiya 645 medium-format system. It sits between the standard 80mm and the wide options in the C-series line, giving a slightly wider-than-normal view on the 645 frame. The C designation places it in the original Sekor C family used with the M645 and later 645 bodies.
This is a manual-focus lens native to the Mamiya 645 bayonet mount, with a focal length of 70mm and a maximum aperture of f/2.8. The aperture is controlled by a mechanical ring on the barrel. Designed to cover the full 645 image circle, it offers a compact, moderately fast optic for general shooting where the standard 80mm feels a touch tight.
At 70mm on 645 the field of view approximates a 43-44mm lens on 35mm, close to a true normal perspective with a mild wide lean. The f/2.8 aperture allows reasonable subject separation on the large format while keeping the lens compact and light. It suits environmental portraits, documentary work and everyday shooting where a slightly broader view than the classic 80mm is helpful.
Used copies of the 70mm f/2.8 appear from time to time but are less common than the 80mm normals. Check the elements for haze, fungus and cleaning marks, confirm the aperture blades are free of oil and close crisply, and test the focus ring for smooth, even resistance. Inspect the bayonet mount and coupling for wear, and look over the front coating for scratches before buying.