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03-26-2012, 03:17 PM   #1
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Very stiff Chinese M42 adapters

About a month ago I ordered three flangeless adapters (knockoffs of the original) for $7.50 each from ebay, hoping that I can remove the metal clip and use them to semi-permanently adapt some M42 lenses to K. They arrived today, and unfortunately they are VERY stiff. I mounted them on the lenses, but these do not rotate in the camera's mount more than, say, 5 degrees. As a simple glance, I didn't see any obvious difference between the original Pentax and these, so maybe you can help me solve my problem.

03-26-2012, 04:10 PM   #2
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I had the same issue with Kipon M42 adapter--which was $22 (has an inner flange to close aperture). I think the conclusion is purchase the Pentax adapter. Too many "stories" about others.
03-26-2012, 04:13 PM   #3
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Make a test placing a self made shim between the lens and the adapter, so it can move just a fraction of a millimeter further into the mount of the body. If this helps (it may or may not), test whether you cannot reach inifinity any more, and/or if you prevent electrical contact to a KAxx mount; in such a case, think about counter measures.

I once posessed a m42 lens where such a shim was the solution of the problem you describe.

Last edited by RKKS08; 03-26-2012 at 04:28 PM.
03-26-2012, 04:16 PM   #4
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Will any of the adapters turn properly in the camera mount without a lens attached?

03-26-2012, 04:29 PM   #5
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I don't think so. I think my problem lies within the adapter itself: it looks just like the original, but even trying to mount it alone on the camera is a much harder job (and the spring is removed!) I have tried my best to take some photos, but I don't think they are very suggestive. I am ready to take the sandpaper out, but I have to know first where is the excess material.


Last edited by kcobain1992; 09-20-2012 at 03:33 PM.
03-26-2012, 04:30 PM   #6
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QuoteOriginally posted by Philoslothical Quote
Will any of the adapters turn properly in the camera mount without a lens attached?
Yes - the original one.
03-26-2012, 04:32 PM   #7
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It may be that the adaptor was machined and then plated, but the machining was to the dimensions of the finished adaptor and the plating increased the dimensions to an unacceptable size
03-26-2012, 04:47 PM   #8
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It's not totally impossible, but I don't think it's the case here. For what it's worth, the knock-offs are very unfinished and edgy compared to the Pentax (the comparison may be unfair, because it's 30 years old!)
If you were right, I think the thread mount would also be tight, but it screws on the lens quite nicely.


Last edited by kcobain1992; 09-20-2012 at 03:34 PM.
03-26-2012, 05:29 PM   #9
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kc
firstly, return "not fit for purpose"? That's what I would do, with a loud complaint.
if you want to persist:
-Dial Calipers, compare with a good lens
-apply a blue marking pen to the adaptor and try to see where it leaves a mark on the body, then file ( but not sandpaper,...and not the body!).
-looking at the k mount, even if you had a lathe, it would be quite tricky to re-chuck it and re-machine, then you also lose the plating.
03-26-2012, 05:55 PM   #10
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In the last pic, it looks like the lugs might be a bit heavier/thicker on the knockoff. It's hard to tell for sure though. I agree with wombat2go, open a dispute, try to get them refunded. Some Chinese sellers will do this without expecting a return of the actual item, so it would save you shipping costs if you can push for that.
03-26-2012, 06:45 PM   #11
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Chat with the seller. You may be doing something wrong. Are you trying to mount them by hand, or are you using the key provided with them?
03-27-2012, 07:31 AM   #12
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QuoteOriginally posted by Laurentiu Cristofor Quote
Are you trying to mount them by hand, or are you using the key provided with them?
Wouldn't that imply that you need 'excessive' force to mount them? If so, I indeed hope that they are cheap crap so the adapter gets damaged and not the mount on the camera
03-27-2012, 09:22 AM   #13
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QuoteOriginally posted by sterretje Quote
Wouldn't that imply that you need 'excessive' force to mount them? If so, I indeed hope that they are cheap crap so the adapter gets damaged and not the mount on the camera
Excessive in what sense? Shiny surfaces + a bit of friction = difficulty mounting them manually.

The advantage of the third party adapters is that you can use them without that retainer clip, unlike the original ones.

If the adapter mounts easily with the key, mount it that way. If it feels like it requires excessive force with the key, then there is a problem.

Once you remove the retainer clip, you can also just screw it on a lens and try mounting it like that - but don't use a lot of force, just in case it is bad and it gets stuck.
03-27-2012, 10:24 AM   #14
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although not really scientific based upon the images shown, the knock off adaptor seems to be one full pixel narrower between the flanges

a proper shot perpendicular to the side of the adaptors but of the exact same view, at perhaps 4 times the resolution posted would confirm this.
03-27-2012, 10:27 AM   #15
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QuoteOriginally posted by kcobain1992 Quote
It's not totally impossible, but I don't think it's the case here. For what it's worth, the knock-offs are very unfinished and edgy compared to the Pentax (the comparation may be unfair, because it's 30 years old!)
If you were right, I think the thread mount would also be tight, but it screws on the lens quite nicely.
it really depends on where the build up is. dont forget this is a 3 d object. threads and other circular things have tolorances so there may still be sufficient clearance between the parts, same with the diameter of the barrel and thebore of the camera body lugs.

BUT look at the other comment I posted, and try to cut and past the section where the locking tab is on the origonal, to the knock off, to me it seems there is less flange to flange distance
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