There are several versions of the 3 element Tair 300mm f4.5 and they were manufactured at
different plants:
Tair-3 4.5/300 – S. A. Zverev Krasnogorsk Mechanical Plant (KMZ).
Tair-3A 4.5/300 - Zagorsk Optical Mechanics Plant, Sergiyev Posad (ZOMZ).
Tair-3 4.5/300 – Kazan Optical Mechanics Plant (KOMZ).
Tair 3 This is the original one, different structurally to the later ones, conventional milled focus ring at the front of the lens, no preset. Often found in M39 mount.
Tair 3S/3C/3 PhS (or FS). The classic "Photosniper" variants of the Tair 300mm f4.5 designed to be mounted on a stock with focus operated by a disk on the underside of the lens. Reviews
here Tair 3A/ 300-A This one - the most conventional of the variants: preset A-mount (see below) lens, focus at the rear end of the lens
Tair 33 This lens was designed for the medium format kiev mount cameras. Lenses for those are very difficult to adapt to other cameras - no review page here. It is a 4 element design (triplet objective)as opposed to the 3 element tairs and there is a
good comparison of a Tair 33 with nikkor ED 300mm f4.5 and Mamiya-Sekor 300mm f5.6 here.
These 300-A's are well known for suffering from stiff focus with age.
The -A in the lens name means that the lens has the interchangeable KP-A/N mount. The design of this mount is like that of a T-mount see pics. It is straightforward to unscrew the grub screws, prise off the mount (don't try to unscrew there is no M42x.75 thread) and replace an M42 with the exterior/bayonet part of a PK T-mount (although I should caution there may be a bit of trial and error/mix and match in getting a good fit). For practical purposes this and other -A lenses can be regarded as a swappable like- T-mount, and this is the case with some other Russian lenses as well eg the
Jupiter 11A, Tair 11A
Focal length: 300 mm
Aperture: F4.5 of the blade 16 with F22
Weight: 1600 grams
Year of issue: 1979, but about 1950-2005
The diameter of the front lens: 72mm;
Minimum Focus: 2.2 m
The mounting thread: M42
History: In 1958, at the world exhibition in Brussels lens received the award of 'Grand Prix'.