I recently obtained an old lens with a Kiev-88 mount, which I intend to use also on a Nikon F camera. Since the K88 to Nikon adapters I could find are very expensive, I got myself a K88 to Pentacon Six adapter and a Pentacon Six to Nikon F adapter, assuming that I should be able to simply stack them to be able to mount the lens. My problem is however, that for some reason, the diameter of the K88-P6 adapter is too large to fit into the P6-Nikon adapter. The difference is less than 1mm, but with metal on metal, not even brute force will join the two adapters.

To understand if the first adapter is too large or if the second adapter is too small, it would be great if by any chance someone could quote me the expected inner diameter of a Pentacon Six mount. Preferably from a technical specification, but if someone has a Pentacon Six and a slide caliper at hand, knowing the diameter of the mount opening on a real model would of course also help.

  • Is it an Arax K88 to P6 adapter? – Michael C Feb 23 '17 at 18:07
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    @MichaelClark am honestly not sure. I just borrowed the K88 to P6 adapter and it does not have any markings, from which I can recognize the manufacturer. I also don't have a real Pentacon Six or lenses to try with right now, but the K88 to P6 adapter I am using fits into a P6 to Pentax 645 adapter I got my hands on today. I will probably get my hands on a 'real' P6 lens to try with the P6 to Nikon adpater tomorrow. – jarnbjo Feb 23 '17 at 19:19
  • Then my guess would be that the P6 to Nikon F adapter you are using is for the "P6" lenses used by the Kiev 60, Kiev 6, or Kiev 6C rather than for the older P6 lenses. – Michael C Feb 23 '17 at 20:32

There's a reference in a flickr group discussion that addresses the issue you are experiencing.

I have this Arax adapter and it works well, but be aware that it will not fit many standard P6 camera mounts (it is larger in diameter than a regular P6 lens). Arax also sells a replacement camera mount ring which solves the problem for any Pentacon Six or Kiev 60. I discovered that my older (silver) P6 mounting ring worked fine (the newer black rings won't). You can also modify these rings on a lathe quite easily. It is the inner diameter of the front flanges that is the issue. This can easily be enlarged, and the ring still works fine with all normal lenses.

If your P6 to Nikon adapter is made for use with Kiev 60, Kiev 6, or 6C lenses then this is your issue.

A solution that doesn't require machining seems to be an additional locking ring. The adapter is on the left, the locking ring is on the right. It is currently listed by this eBay seller as an add-on to the K88 to P6 adapter. You may try contacting the seller and see if purchase of only the locking ring is possible.

enter image description here

Some sellers list P6 to Nikon F adapters that also include a K88 to P6 ring. If sold together one would presume the smaller additional ring properly fits the larger P6 to Nikon F adapter.

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  • I ordered the combined P6/K88 to Nikon adapter you are linking to. As you say, if they are sold together, they are very likely to fit :) – jarnbjo Feb 25 '17 at 13:01

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