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Komura mount help?
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PostPosted: Sat Jun 09, 2018 5:01 am    Post subject: Komura mount help? Reply with quote

My recently purchased Sankyo Kohki Komura 135mm f/2.8 lens has a mount which I'm not familiar with. After some internet searching I think it may be a Unidapter in Petri mount.

Can someone tell me if I'm right?

And whatever the mount may be, is there an adapter to fit it onto my Canon DSLR?


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#2


PostPosted: Sat Jun 09, 2018 6:18 am    Post subject: Reply with quote

Yes. Unidapter in Petri mount.


PostPosted: Sat Jun 09, 2018 6:22 am    Post subject: Reply with quote

You are right, its a Unidapter in Petri mount.
You have a problem. You need a Unidapter in a more useful mount.
There are Petri adapters for mirrorless mounts, but not for DSLRs that I know of.

Short of finding another Komura Unidapter lens with a better mount or a hack of some sort ... Maybe with a T-mount as a starting point.


PostPosted: Sat Jun 09, 2018 7:33 am    Post subject: Reply with quote

Ah, a difficult mount for EOS. Fortunately the lens didn't cost me very much. I guess I'll start watching ebay for a different Unidapter.

Thank you both for the confirmation and suggestions!


PostPosted: Sat Jun 09, 2018 6:26 pm    Post subject: Reply with quote

T-mounts have 42mm threads, Unidapters have 44mm threads. Almost the only way to get a Unidapter is to buy a lens with the one you want.

Not sure if Unidapter has the same 55mm register (distance to film plane) as T-mount.


PostPosted: Sat Jun 09, 2018 11:03 pm    Post subject: Reply with quote

T-mounts could be an adapter starting point. They have a removable inner ring .
There are many options for mounting inside the mount, with the ring removed.

Epoxy, self-threading into a hardening filler, cutting M44 thread into that inner ring, etc.


PostPosted: Sun Jun 10, 2018 2:10 am    Post subject: Reply with quote

Thanks, guys. I prefer to keep my lenses original, but I'm glad to know there are alternatives to a Komura adapter. I have a few spare T mounts, so I'll keep Luis' suggestion in mind.


PostPosted: Mon Jan 28, 2019 5:31 am    Post subject: Reply with quote

Update:

I'm still looking for a Unidapter which will allow me to use this lens on my cameras, but I've experimented with a "hollow" T mount as suggested. The fit was close, but not quite right. I don't want to resort to glue, etc., so I'll wait for a proper adapter.

And regarding the Unidapter mount, John and Luis both mentioned 44mm. I guess I have a variation because my 135's mount is about 48mm in diameter. Thread pitch is .75mm.



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Tim


PostPosted: Mon Jan 28, 2019 8:08 am    Post subject: Reply with quote

There is a Komura 135 2.8 on the bay right now, with a non functioning aperture and lots of fungus, for $8 + shipping (from Japan). It looks a little different to your copy though... That might be an option though, to lurk around waiting for a low price donor lens.

Edit: at 48mm I wonder if something like this would work:
https://www.adorama.com/kam48nkf.html


PostPosted: Mon Jan 28, 2019 6:02 pm    Post subject: Reply with quote

Thanks for the tips, Alun!

That $8 ebay lens has a Minolta mount which wouldn't be the best choice for adapting to my Pentax and Canon DSLRs. I think I'd need a M42 or Nikon mount. And I don't think that lens is a Unidapter, anyway. Komura seems to have made several different mounts...

Hmm, that 48mm Scope adapter looks promising! I think I'll order one and give it a try. Smile
I'll let you know how it works.


Tim


PostPosted: Sat Feb 02, 2019 7:13 am    Post subject: It works, but... Reply with quote

My telescope adapter has arrived and, yes, it does work - but with some caveats.

Adorama.com didn't have the 48mm adapter in M42 mount, so I bought a M42 from ebay instead. I can't figure out how to make the ebay link work, so if anyone is interested, here's the listing name for the adapter I bought:

Astromania T / T2 Male Thread 48mm to 42mm Female M48 to M42 Telescope Adapter




My adapter has the correct 48mm diameter and .75mm thread pitch to fit securely on the Komura's mount. However, the male side of the 48mm adapter also has a .75mm thread pitch which means my 1mm pitch M42 to Canon EOS adapter doesn't fit securely. Especially because the male thread on the 48mm adapter is really short. So the fit isn't solid and secure, but it does work. And it gives focus to just a bit beyond infinity.

When I placed a M42 T2 adapter (.75mm pitch) between the 48mm adapter and my M42 to EOS adapter, the fit was solid and secure. But the focus range was then limited to about 1 meter to 3 meters...

The telescope adapter is better than nothing, but it's not a true substitute for a genuine Unidapter.

Thanks again to Alun for the adapter link!


PostPosted: Sat Feb 02, 2019 7:53 am    Post subject: Reply with quote

https://www.ebay.com/itm/Astromania-T-T2-Male-Thread-48mm-to-42mm-Female-M48-to-M42-Telescope-Adapter-/291902981274


PostPosted: Sat Feb 02, 2019 8:44 am    Post subject: ebay link Reply with quote

Thanks for the help, Lightshow. That's the adpapter I bought and that seller gave me excellent service.

And after some experimenting, I now understand how to make the ebay link work!


PostPosted: Sat Feb 02, 2019 2:06 pm    Post subject: Reply with quote

Sorry I'm so late to the party, SS, but this might be an option as well M48 -> EOS:

Click here to see on Ebay


All the best,

Paul


PostPosted: Sat Feb 02, 2019 4:24 pm    Post subject: Reply with quote

Hi Paul,

Yes, I think you're right about that M48 to EOS adapter. I wanted to try a M42 version first as a "one size fits all" adapter for both my Canon and Pentax cameras.

I'm satisfied with the results of my experiment and am now willing to wait for a M42 Unidapter at a good price.
Getting a bargain is half the fun for me!

Thank you for the suggestion.


Tim


PostPosted: Mon Aug 10, 2020 11:57 pm    Post subject: update Reply with quote

Bump.

Time flies! It's been over two years since I first asked for help with my Komura 135. And I still haven't found a replacement Unidapter, so I decided to follow pdccameras' suggestion and buy a M48 to EOS adapter.

The adapter arrived today and it works! Smile
It screws onto the lens mount fully and gives normal focus range: 1.5m to infinity.

Click here to see on Ebay


PostPosted: Tue Aug 11, 2020 12:15 am    Post subject: Reply with quote

Congrats


PostPosted: Tue Aug 11, 2020 9:32 am    Post subject: Reply with quote

That's cause for celebration.


PostPosted: Wed Aug 12, 2020 5:01 am    Post subject: Reply with quote

Laugh 1 Yes, thank you calvin83, Lightshow and all who offered encouragement!

The M48 adapter isn't as sleek as the Unidapter, but I don't think my lens will care!


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PostPosted: Sat Aug 22, 2020 12:27 pm    Post subject: Reply with quote

Gee, I don't know why I said the Unidapter was 44mm, it's 48mm on my 100/1.8. (That lens is a lot of fun!)

Perhaps I should buy a 48mm to Pentax K adapter so I can use it more directly on my Pentax K-1. Right now I have a CS (M42) Unidapter on it.