Zeiss's low-distortion Biogon wide — the 35mm f/2.8 adapted to Leica Thread Mount.
The Biogon 35mm f/2.8 is a classic Zeiss wide-angle built on the symmetrical Biogon formula, associated with the Zeiss rangefinder line. Examples in Leica Thread Mount let this wide be used on screw-mount and adapted bodies. Native Biogons of this type were made in Contax rangefinder mount, with LTM examples being conversions or adaptations.
It is a manual-focus rangefinder-coupled lens with a 35mm focal length and a maximum aperture of f/2.8. The Biogon design is close to symmetrical and sits deep toward the film or sensor plane, which gives it low distortion and even illumination but can create clearance issues on some bodies.
The 35mm Biogon is known for low distortion, high across-frame sharpness and even field illumination, which suits architecture, landscape and street work where straight lines and corner quality matter. It renders with good contrast and holds up well when stopped down.
As vintage optics, used copies need careful inspection for haze, cleaning marks, coating wear and element separation, plus a check of focus and aperture feel. Because the rear group sits deep, confirm the specific example clears the shutter or sensor on your intended body, and verify coupling on converted lenses. It adapts to Leica M and to mirrorless cameras via an adapter, subject to that clearance check.