Distagon 1.2/25mm

It seems to be a lens for 16mm film, but my reference book states that it is for 35mm film.

Specification of DISTAGON 1.2/25MM

Manufacturer "OPTON" (Germany)
Lens system -
Focal length f' 25.9 mm
Angle of view 2ω' 57°06'
Effective relative aperture f:nэ 1:1.4
Lens length Σd 78 mm
Front focal length S -
Back focal length S' 27.2 mm
Flange focal distance Z -
Block length B 88 mm
Block max. diameter D 76 mm
Rear diameter D' 41 mm
Front element diameter d1 47.5 mm
Rear element diameter d2 27.0 mm
Mount thread -
Distance from rear end of the housing
to the focal plane
l 26.2 mm
Aperture blades quantity ?
Frame size 16x22 mm
Weight 550 g

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