Carl Zeiss Distagon T* 28mm f/2.8 (C/Y) vs Carl Zeiss Jena Flektogon 35mm f/2.4

What actually differs

• The Carl Zeiss Jena Flektogon 35mm f/2.4 is 0.4 stops faster: f/2.4 against f/2.8.
• The Carl Zeiss Jena Flektogon 35mm f/2.4 is cheaper. Typical used value is $210 against $320, a gap of $110 (roughly 1.5x). Ranges: $130 to $380 versus $180 to $550.
• The Carl Zeiss Jena Flektogon 35mm f/2.4 is longer at 35mm against 28mm, a 7mm difference that tightens framing slightly and increases background magnification.
• Production of both began around 1975 (1975-2005 and 1975-1990).
• They use different mounts, Contax/Yashica and M42, so each needs its own adapter. Both reach infinity on mirrorless bodies with a plain mechanical adapter.
• Construction differs: 7 elements in 7 groups for the Carl Zeiss Distagon T* 28mm f/2.8 (C/Y), 6 elements in 5 groups for the Carl Zeiss Jena Flektogon 35mm f/2.4.

Which one to buy

On the catalog data the Carl Zeiss Jena Flektogon 35mm f/2.4 wins on the 0.4 stops of extra speed and the $110 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.