Six-lens super-aperture anastigmat of the "Planar" type for medium focal observation 1). An analogue of the optical design is the Carl Zeiss Jena Biotar 1.5 / 75 lens (1938) 2).
Equipped with an iris diaphragm and a ring before its installation.
By the nature of the application, 3) refers to medium-sized portrait lenses (half-length portrait).
Produced by the Krasnogorsk Mechanical Plant of a large number of varieties for SLR cameras with threaded optics: M39
Focal Length: 85mm (85.18mm)
Relative aperture: 1:1.5
Viewing angle: 28°
Frame size: 24×36mm
Number of lenses/groups: 6/4
Front top focal length: -26.85mm
Rear top focal length: 44.52mm
Distance from first to last surface: 81.53 mm
Surface light diameter: ⌀56.9 mm
Surface light diameter: ⌀36.8mm
Resolution according to specifications (center / edge):
Helios-40 - 32/16 str/mm
Helios-40-2 - 36/17 lines/mm
Distortion: ≈ 0.1% barrel
Light transmittance:
Helios-40 - 0.75
Color formula: 10--0--4
Enlightenment type:
old releases - chemical, single layer 6
Dimensions:
Helios-40 lens length with caps: 110 mm
Helios-40-2 lens length without cover: 95 mm
maximum frame diameter: 82mm
Weight (passport):
Helios-40 - 1090 g