Asahi Pentax Super-Takumar 55mm f/1.8 vs Carl Zeiss Jena Biotar 58mm f/2

What actually differs

• The Asahi Pentax Super-Takumar 55mm f/1.8 is 0.3 stops faster: f/1.8 against f/2.
• The Asahi Pentax Super-Takumar 55mm f/1.8 is cheaper. Typical used value is $70 against $230, a gap of $160 (roughly 3.3x). Ranges: $35 to $130 versus $120 to $550.
• The Carl Zeiss Jena Biotar 58mm f/2 is longer at 58mm against 55mm, a 3mm difference that tightens framing slightly and increases background magnification.
• The Carl Zeiss Jena Biotar 58mm f/2 is the older design; production began around 1936 against 1958 for the Asahi Pentax Super-Takumar 55mm f/1.8 (1936-1960 versus 1958-1971).
• Both use the M42 mount, so one adapter serves either lens on a mirrorless body.
• Construction differs: 6 elements in 5 groups for the Asahi Pentax Super-Takumar 55mm f/1.8, 6 elements in 4 groups for the Carl Zeiss Jena Biotar 58mm f/2.

Which one to buy

On the catalog data the Asahi Pentax Super-Takumar 55mm f/1.8 wins on the 0.3 stops of extra speed and the $160 lower typical price, and the Carl Zeiss Jena Biotar 58mm f/2 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.