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How to convert a Pentax K-1 to Nikon mount
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Lou Jost



Joined: 04 Sep 2015
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Location: Ecuador

PostPosted: Fri Aug 10, 2018 4:16 pm    Post subject: How to convert a Pentax K-1 to Nikon mount Reply with quote

The Pentax K-1 is a great value, and when pixel-shifting can be used, image quality is better than any current Nikon camera at any price. But all my lenses are Nikon, and many of them have no equal in the Pentax line-up.

So I bought a Pentax K-1 and converted it (semi-reversibly) to a Nikon mount, maintaining infinity focusing on all Nikon lenses. This is possible because the flange distance for Nikon is just 1mm greater than for Pentax. This is too little space for a normal adapter, but it is enough space that a suitable 1mm thick Nikon camera mount can be mounted on top of the Pentax mount.

I got the courage to do this by reading an online account of someone who converted their Pentax camera to Nikon using only a file as a tool.
http://forum.mflenses.com/pentax-p30t-and-p50-nikon-f-body-mount-conversion-t29918.html
He just replaced the Pentax mount with a Nikon one, but that doesn't preserve infinity focus. My way preserves it.

I used the same screw holes as the Pentax mount. Just like the other guy who did this, my only tool was a narrow metal file. I filed channels in the Nikon lens mount (obtained from an old Nikon-to-Canon Novoflex adapter I had on hand) so the bigger-headed Pentax screws would not protrude (and so that they would sit deeper in the Pentax screw holes when they are tightened). Then I filed slots on the edges of the Nikon mount so that the screws would enter the Pentax holes (the Nikon screw holes were too near the center axis to match the Pentax holes).



I won't win any prizes for precision worksmanship, but it is good enough.

I had to file off the lens mounting flanges on the Pentax mount so that the Nikon mount would sit flat. This is the non-reversible part. I will have to buy a new Pentax lens mount (probably fine to get one from an auto Pentax extension tube) in order to revert to the original condition. I put tape on the channels to prevent light leaks, but the lens should block the light coming from there anyway.



I checked infinity focus with a Nikon telephoto lens and it is perfect. However there is no locking pin to hold the lens in place, so care is needed.

In retrospect I should have not used the Nikon screw holes, I should have just cut slots where needed, and I should have lined up the Pentax's own locking pin with an appropriately-drilled hole in the Nikon mount, so I could have used the Pentax pin and lens release button. Maybe I'll make another one with that design. This only took a few hours. With a proper set of machine tools it would have taken minutes.
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johan



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PostPosted: Sat Aug 11, 2018 12:13 am    Post subject: Reply with quote

Brave...! Delighted that it worked out for you!
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mjkzz



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PostPosted: Sat Aug 11, 2018 3:25 am    Post subject: Reply with quote

wow.
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Lou Jost



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PostPosted: Sat Aug 11, 2018 6:36 am    Post subject: Reply with quote

I wish I could find slightly longer screws, I've lost about half a millimeter of traction since they now go through the Nikon mount...
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RobertOToole



Joined: 17 Jan 2013
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PostPosted: Sat Aug 11, 2018 9:55 am    Post subject: Reply with quote

Great subject Lou. I am sure a lot of people are really interested in this, I know I am.

I was told, tell me what you know, if you do not need infinity focus, I do not, you can just use F-mount lenses with K-mount but you lose electronics and the lens pin-lock wont work? Is this right?

I was also told that you can drill the K mount so the F-mount lens pin will work.

Also was there a commercial K-mount to F-mount adapter mount available that allows Infinity focus. I think it was from Singapore. Are they still available?

Robert
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lothman



Joined: 14 Feb 2009
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Location: Stuttgart/Germany

PostPosted: Sat Aug 11, 2018 3:09 pm    Post subject: Reply with quote

are this metal chips inside the camera?
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Lou Jost



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PostPosted: Sat Aug 11, 2018 3:43 pm    Post subject: Reply with quote

Lothman, they might be.....I had washed and air-blasted all the parts after filing (and of course I did not do any filing near the camera) but maybe there were a few semi-loose pieces that were dislodged when I screwed the mount onto the camera. Anyway I blew it out again with compressed air, I hope that got rid of it....
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Lou Jost



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PostPosted: Sat Aug 11, 2018 3:49 pm    Post subject: Reply with quote

Robert, F-mounts loosely fit int K mounts but it is not sturdy. And as you say, you lose infinity.

The lens mounts you are thinking of from Singapore are the Adaptist multi-mounts, which fit a variety of lenses in the same mount, including Nikon and Pentax. However this type of mount cannot maintain infinity focus for all the mounts, obviously. Nikon infinity focus is not preserved. They are currently out of stock but the owner of the company told me that he is trying to make more.

I don't know of a commercially available infinity-preserving Nikon mount to replace the Pentax mount. If you find out about that, I'd be interested. It would be much sturdier than my DIY job.

Why don't you need infinity focus? Even if all you ever want to do with this is studio macro, if you ever want to use Nikon or Sigma lenses with close-range corrections, the corrections won't be correct unless you have infinity focus where it belongs.
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RobertOToole



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PostPosted: Sat Aug 11, 2018 4:20 pm    Post subject: Reply with quote

Lou Jost wrote:
Robert, F-mounts loosely fit int K mounts but it is not sturdy. And as you say, you lose infinity.

The lens mounts you are thinking of from Singapore are the Adaptist multi-mounts, which fit a variety of lenses in the same mount, including Nikon and Pentax. However this type of mount cannot maintain infinity focus for all the mounts, obviously. Nikon infinity focus is not preserved. They are currently out of stock but the owner of the company told me that he is trying to make more.

I don't know of a commercially available infinity-preserving Nikon mount to replace the Pentax mount. If you find out about that, I'd be interested. It would be much sturdier than my DIY job.

Why don't you need infinity focus? Even if all you ever want to do with this is studio macro, if you ever want to use Nikon or Sigma lenses with close-range corrections, the corrections won't be correct unless you have infinity focus where it belongs.


Thanks the reply Lou.

Once I pick up a Pentax I plan to use that body for use with objectives and the Min 5400 etc. When I go outdoors with my macro lenses I will probably bring my D850 anyway. I tend to buy specific equipment for a certain task.

Good point on the CRC correction, I never add extension to a normal floating close range corrected macro lens because of that since I am a little paranoid of missing out on the correction.

Thanks for all the info.

Looking forward to seeing what you come up with the new Pentax.

Best,

Robert
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Lou Jost



Joined: 04 Sep 2015
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PostPosted: Sat Aug 11, 2018 5:19 pm    Post subject: Reply with quote

Robert, if you don't need infinity focus, there is no need to change mounts. Until I changed my mount, I just used a readily available Nikon-to-Pentax adapter with an optical element (to give infinity focus, but the lens is crap); I knocked out the optics, filed out the hole, and used that. Rock solid and you can always take it off and use Pentax lenses if you want.

I also took a Nikon extension tube and removed the male mount and replaced it with a Pentax lens mount filched from a fungus-filled $15 lens I got on ebay. That also worked .

These are much better solutions than my hack mount, if you won't ever use a lens with CRC. But even many of my studio macro tube lenses, including my best one, use CRC, so I want infinity focus.
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RobertOToole



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PostPosted: Sat Aug 11, 2018 6:21 pm    Post subject: Reply with quote

Thanks for the ideas Lou.

Its easier than I thought to go from P/K to M42:

Pentax K to M42 x 1.0




And then to M52 / SM2, I already own this one Smile

SM2 to M42 x 1.0



Robert
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Lou Jost



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PostPosted: Sat Aug 11, 2018 6:23 pm    Post subject: Reply with quote

If you don't need infinity focus, that's a great solution.
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lothman



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PostPosted: Sun Aug 12, 2018 4:55 am    Post subject: Reply with quote

RobertOToole wrote:
Thanks for the ideas Lou.

Its easier than I thought to go from P/K to M42:


Robert


Robert,
I had Pentax until end of last year. The PK/M42 adapter you showed allows infinity on old M42 lenses and sits flush in the Pentax when mounted. For unmounting you need a small tool to get it out, Youtube-Video. So when you don`t need the M42-infinity the I recommend another adpater with a flange since they are much more easy to mount/dismount.
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Lou Jost



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PostPosted: Sun Aug 12, 2018 5:06 am    Post subject: Reply with quote

I have now added epoxy between the Nikon and Pentax rings. I was getting nervous about the stress on the thin metal around the screw slots on the Nikon ring.
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RobertOToole



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PostPosted: Sun Aug 12, 2018 10:04 am    Post subject: Reply with quote

lothman wrote:
RobertOToole wrote:
Thanks for the ideas Lou.

Its easier than I thought to go from P/K to M42:


Robert


Robert,
I had Pentax until end of last year. The PK/M42 adapter you showed allows infinity on old M42 lenses and sits flush in the Pentax when mounted. For unmounting you need a small tool to get it out, Youtube-Video. So when you don`t need the M42-infinity the I recommend another adpater with a flange since they are much more easy to mount/dismount.


Thanks for the advice Lothar.
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