Canon FD 35mm f/2 (concave) vs Carl Zeiss Distagon T* 28mm f/2.8 (C/Y)

What actually differs

• The Canon FD 35mm f/2 (concave) is 1 stop faster: f/2 against f/2.8.
• The Canon FD 35mm f/2 (concave) is cheaper. Typical used value is $280 against $320, a gap of $40. Ranges: $150 to $500 versus $180 to $550.
• The Canon FD 35mm f/2 (concave) is longer at 35mm against 28mm, a 7mm difference that tightens framing slightly and increases background magnification.
• The Canon FD 35mm f/2 (concave) is the older design; production began around 1971 against 1975 for the Carl Zeiss Distagon T* 28mm f/2.8 (C/Y) (1971-1979 versus 1975-2005).
• They use different mounts, Canon FD and Contax/Yashica, so each needs its own adapter. Both reach infinity on mirrorless bodies with a plain mechanical adapter.
• Construction differs: 9 elements in 8 groups for the Canon FD 35mm f/2 (concave), 7 elements in 7 groups for the Carl Zeiss Distagon T* 28mm f/2.8 (C/Y).

Which one to buy

On the catalog data the Canon FD 35mm f/2 (concave) wins on the 1 stop of extra speed and the $40 lower typical price, and the Carl Zeiss Distagon T* 28mm f/2.8 (C/Y) gives up nothing measurable in return except its own rendering, described below. Condition and variant matter more than the spec sheet at these prices.

Minimum focus distance, weight, and measured sharpness are not in the catalog, so this comparison does not claim anything about them.