Bayonet joint “Б” (Pentacon Six)

Lenses with a “B” bayonet joint of (Pentacon Six) can be delivered on the cameras Nikon by means of the Soviet KP-6 adapter or by means of Pentacon Six adapter – to Nikon
Lenses with a bayonet joint “B” (Pentacon Six) can be delivered on the cameras Canon by means of the Soviet KP-6 adapter, having added to it the adapter Nikon-Canon or by means of Pentacon Six adapter – Canon
The bayonet joint B, is better known as the Bayonet joint of Pentacon Six or P6 — fixing type of photographic lenses and cameras.

pentacon
In comparison with a 35-mm film, the lens has the big area of the received frame therefore the angle of the image shall be calculated with a bayonet joint of B proceeding from a frame diagonal in 85 mm, against 43 mm (at a 35-mm film).

CZJ Flektogon 50/4 is wide-angle for the camera with a bayonet joint B and normal for the camera with a 35-mm film.

Installation of lenses requires involvement of both hands therefore their change on a weight causes small difficulties.
It is necessary to mark that the principal focal distance of a lens with a bayonet joint B doesn’t need in terms of the equivalent focal distance of a 35-mm film. Count is necessary only in case of existence of a crop-factor directly at the used camera.

Bayonet joint “B”

The bayonet joint “B” was copied from early cameras Hasselblad and therefore they are mechanically compatible. Besides, lenses with a bayonet joint “B” can be delivered on cameras:

Nikon
bayonet joint “B” on Nikon by means of the Soviet KP-88/N adapter.
or by means of a linking of adapters a bayonet joint “B” – Pentakon six + Pentacon six – Nikon

Canon
bayonet joint “B” on Canon by means of the Soviet KP-88/N adapter, having added to it the adapter Nikon-Canon
or by means of a linking of adapters with a bayonet joint “B”- Pentakon six + Pentacon-Canon

M42 -Canon EOS
Fixing of M42 is very widespread threaded fastening. Similar fixing happens with M39 which turns into M42 by means of the transition ring of M39-M42.
Working segment of M42 = 45.5mm
Working segment of Canon EF: 44mm.

It allows to manufacture the adapter which theoretically shall be 1.5mm. In practice it happens from 1.37 to 1.6mm that is urged to compensate errors in case of bayonet joints manufacture of old lenses. Somewhere 1.5mm adapter won’t put on i.e. it is too thick (and there will be no focusing on infinity), and somewhere 1.37mm will dangle. Therefore it is necessary to try.

m42-eos

Nikon-Canon EOS

Both fixings are bayonet. It is possible to fix only Nikon lens on the Canon. Vice versa it is impossible with the adapter without lens i.e a working segment of Nikon is more, than at Canon and therefore on Nikon it is so difficult to fix many old lenses, for example, with M42 thread.

nikon-canon adapte