Tair lens series

“Tair” is a family of telephoto lenses of increased aperture, produced in the USSR for SLR cameras and movie cameras.The family’s optical scheme was developed by Soviet optician David Volosov in 1943 for remote photographic reconnaissance in low light conditions. The name “Tair” is the abbreviated name of the star Altair without the Arabic article “al”. Tair lenses formed the basis of all Photoguns of the “ Photosniper ” type.

Technical features

The original design consists of three lenses, sufficient for low angular fields. If it is necessary to expand the field of view, a fourth lens is added, correcting aberrations increasing along the edge of the image field. Regardless of the number of lenses, all Tair telephoto lenses are built according to the classical Galileo telescope design with a strong positive component in the front and negative in the back. The main feature of Tair lenses is the large thickness of the negative meniscus in the back. As a result, the lens serves as a compensator, correcting astigmatism and the inherent curvature of the image surface.

As a result, the fourth Seidel coefficient, which determines the astigmatic curvature, is only about 0.1 (0.25 is fair, 0.2 is good, 0.15 is excellent, 0.1 is excellent). Therefore, with a very simple lens design, the image quality is uniform over the entire field. However, with only three lenses, there is no parameter that can control the distortion. Distortion with a positive sign is present in the Tair, but due to the small angular fields it is small and practically invisible.

Specification

The parameters of the lenses are given in accordance with the GOI catalog of 1963.

Lenses “Tair”
Model Format Focal length Aperture ratio Corner field
APO Tair-1 24 × 36 mm 298.73 mm ƒ / 4.5 8 °
Tair-2 24 × 36 mm 300 mm ƒ / 4.5 8 °
Tair-3 24 × 36 mm 300 mm ƒ / 4.5 8 °
Tair-4 24 × 36 mm 600 mm ƒ / 4.5 4 °
Tair-7 8 × 8 cm 300 mm ƒ / 4.5 22 °
Tair-8 8 × 8 cm 500 mm ƒ / 4.5 13 °
Tair-10 9 × 9 cm 750 mm ƒ / 4.5 10 °
Tair-11 24 × 36 mm 133.2 mm ƒ / 2.8 18 °
Tair-12 35 mm 150 mm ƒ / 4.0 11 °
Tair-13 16 mm 75 mm ƒ / 5.6 10 °
Tair-14 35 mm 180 mm ƒ / 8.0 9 ° 30 ′
Tair-15 16 mm 50 mm ƒ / 4.0 15 °
Tair-16 9 × 9 cm 500 mm ƒ / 4.5 14 °
Tair-18 24 × 36 mm 300 mm ƒ / 2.5 8 °
Tair-19 24 × 36 mm 500 mm ƒ / 3.0 5 °
Tair-30 6 × 9 cm 300 mm ƒ / 4.5 20 °
Tair-33 6 × 6 cm 302.6 mm ƒ / 4.5 15 °
Tair-38C 24 × 36 mm 135 mm ƒ / 2.8 18 °
Tair-40 16 mm 111 mm ƒ / 5.0 5 °
Tair-41 16 mm 50.44 mm ƒ / 2.2 15 °
Tair-44-T 24 × 32 mm 300 mm ƒ / 4.5 7 ° 30 ′
Tair-45-T 24 × 32 mm 180 mm ƒ / 2.8 13 °
Tair-46-T 24 × 32 mm 500 mm ƒ / 5.6 5 °
Tair-47-T 24 × 32 mm 400 mm ƒ / 4.5 6 °
Tair-48-T 24 × 32 mm 210 mm ƒ / 3.5 10 °
Tair-51-T 24 × 32 mm 135 mm ƒ / 3.0 17 °
Tair-52-T 24 × 32 mm 1000 mm ƒ / 8.0 2 ° 20 ′
Tair-56 24 × 36 mm 150.1 mm ƒ / 2.8 16 °

The optical scheme ” Tair ” was also used in long-focus lenses of the line of professional film-making optics OKS1-200-1, OKS1-300-1 and OKS2-150-1. Further improvement led to the development of apochromatic lenses of the Apo-Tair series with low-dispersion elements.

 

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