One of the aperture blade has missing pin, one blade isn't its right place, but can set the aperture, as You can see on pictures.
Good M42 Carl Zeiss Jena BIOTAR 2/58 Red T Lens * 12 Blades * 58mm F/2
SERVICED EXCELLENT M42 CARL ZEISS JENA BIOTAR 1Q RED T 2/58 EXCELLENT CONDITION 5.8
Carl Zeiss Jena Biotar 58mm F2 Exakta Mount Lens, Working Tatty! Ok Optics
SERVICED EXC M42 CARL ZEISS JENA BIOTAR Red T 1:2/5.8cm 17 Blades 2.0 58mm
Carl Zeiss Jena Biotar 58mm f2 Lens Red T version EXA mount
Carl Zeiss Jena Biotar F2 5.8 cm Exa mount
