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05-11-2017, 06:15 PM   #1
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Pentax M42-to-K-Mount Adaptor STUCK to lens

Hello, all...
I hope a more experienced hand can help me with a strange problem I've encountered. I recently purchased a lovely little ME Super with motor drive and three K-mount lenses.
However, remembering those sharp and elegantly well built SMC Takumars I used many years ago with Spotmatics, I thought I'd engage in some sentimental moments and purchase a few of these for use, stopped down, on the ME Super. To make sure I was doing this the "right" way, I also purchased a genuine Pentax OEM adapter.
Seems there are two schools of thought for using the Pentax adapter: (1) insert it first into the K-Mount body and then screw in the M42 lens or (2) screw the lens into the adaptor and then mount it, bayonet-style, into the body.
I can not remember which technique I used - it was several months ago - but apparently, it was the wrong one.
Problem is the adapter has clamped itself onto the screw mount of my "new" Takumar 150/4 lens and, like a face-hugger in "Aliens," it won't let go!
I've tried to unscrew the 150 from this infernal thing using rubber grippers, but to no avail.
I understand the procedure for removing the adapter from a K-Mount camera by pushing in the release with the tip of a ball point pen or similar object, and that worked fine on the second such Pentax adapter I purchased. However I cannot find any corresponding "release on the "back" side of the adapter in question. I tried mounting the adaptor-stuck-to-150 lens on the ME Super and made sure it locked, thus hoping to unscrew the 150 from the camera, but all I succeeded in doing was removing the lens with the adapter still attached.
Is this, by a chance, a known issue? More to the point, can anyone assist in terms of how to remove this lens from the adapter?
Many thanks!
Steve

05-11-2017, 06:20 PM   #2
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use a jis screw driver and remove the screw from the clip then use a lens cap to screw it off. PS try the lens cap FIRST
05-11-2017, 06:34 PM   #3
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There are a few threads about this issue. See this one, for instance: HELP! M42 adapter stuck on lens! - PentaxForums.com

It's hard to get a grip on the adapter. Best way, I find, is to use a rear K-mount lens cap to "grip" the adapter and then you'll have more holding power to unscrew the lens from the adapter. The threads are probably just binding a bit. I don't think it should make any difference when mounting the lens on whether you mount he adapter first, and then screw in the lens, or screw the lens in first and then mount the adapter and lens. I sometimes do it the one way and sometimes the other.
05-11-2017, 07:55 PM   #4
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The spring clip should prevent you from being able to remove the adapter from the camera body unless you press in the clip. Be thankful that the adapter and lens is not getting stuck to the body.

Are those new adapters or are they used?

If used the clip may have been damaged or the retaining screw for the clip replaced with one too long. This is a problem with some of the third party knock-off copies. The screw jams on the threads of the lens. As suggested above try removing this screw.

Another possible hang up is the auto/manual release pin on lens mount. This pin can some times jam on third party adapters. If the adapter is screwed down all the way and you can't move the switch from from auto to manual then you'll need a feeler gauge or something to press the pin in so you can remove the adapter. If this is the case the adapter is probably defective.

It doesn't really make much difference if you mount the adapter on the lens or the body first. The instructions that came with the adapter or in the camera manuals seemed to go either way. I find it easier to mount long or heavy lenses by putting the adapter on the lens first.

05-11-2017, 08:57 PM - 1 Like   #5
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Temperatura. Some time ago I was unable to unscrew polarizer filter from my 28-70 . After I Put the lens outdoor in a very cool day for half hour and I was easy to do it.
05-11-2017, 09:06 PM   #6
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If it's not stuck in the camera, shouldn't be a problem with the little clip, but rather just the 42mm screw mount. I have a tiny hobby vise I grab onto the adapter with, then just turn the lens with two hands. You could also use a large pair of pliers or water pumps as a spanner wrench in the mount-flanges. I'd have one person turn the lens with two hands, and the other operate the pliers/spanners.
05-11-2017, 09:09 PM   #7
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QuoteOriginally posted by niceshot Quote
use a jis screw driver and remove the screw from the clip then use a lens cap to screw it off. PS try the lens cap FIRST
Wow - so nice to have a forum such as this when one is feeling so in-over-his-head-frustrated!

Thank you all, Not a Number, MarkJerling, and niceshot.

It was a bit of a struggle to unscrew the tiny screw, but it finally budged and out it popped, along with the clip. At first, I thought I might have broken the screw, as under magnification it appears to have only only two threads (?). Even with it and the clip out, I was afraid I'd farkled it, when I couldn't budge the lens. I then followed another of your suggestions to use the K-mount lens cap to get some better grip on it...and finally, the M42 screw mount turned and came out. Whew to the umpteenth power! The lens thread appears undamaged and the M42 lens cap screws on smoothly. Guess it could've been a lot worse!

To answer another of your questions, as far as I can tell, the adapter is genuine, not a knock-off - it is silver/chrome and has black letters engraved "Asahi Pentax" and "Japan." This one had been previously used by the seller, so I suppose that might be a factor. That is why I bought the second, which was listed as NOS. Based on the adventure of freeing the lens, not sure I'm going to try reassembling this one ;-)

Now that the topic has been raised, may I also ask if this design does in fact allow a Takumar M42 mount lens to align such that its red focus mark is at top center. I recall having to turn one of the Taks I purchased (not sure if it was this one) to get the mark lined up looking as I guessed it should. If it was in fact this lens with this adaptor, I suppose that might hint as to what went wrong, but just guessing on that.
Again, many thank to you all for this prompt and worthwhile help!
Steve
05-12-2017, 01:36 AM   #8
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QuoteOriginally posted by MewersDad Quote
Now that the topic has been raised, may I also ask if this design does in fact allow a Takumar M42 mount lens to align such that its red focus mark is at top center. I recall having to turn one of the Taks I purchased (not sure if it was this one) to get the mark lined up looking as I guessed it should. If it was in fact this lens with this adaptor, I suppose that might hint as to what went wrong, but just guessing on that.
A few members have reported that the focus mark will align to the 12 o'clock position but the majority of the members that responded to the same question say their lenses line up to around the 11 o'clock position. I have three genuine adapters - one marked "PENTAX Japan" and two marked "PENTAX Philippines". All of my screwmount lenses will align to around the 11 o'clock position. All of these lenses except a Takumar 135mm line up to the 12 o'clock position on my Asahi Pentax Auto Bellows. The 135mm goes a touch past say to 12:15 o'clock. I speculated perhaps the "Asahi Pentax" branded adapters lined up to 12 o'clock but this doesn't seem to be the case. It may just be individual variation or perhaps only a few production runs of the adapter line up to center. Who knows?

It has been speculated that the reason for the offset was due to the overhang on the prism housing on K-mount bodies but the overhang on the early K-mount bodies rarely goes beyond the bayonet flange. Again, who knows?

You may want to reassemble the misbehaving adapter and compare the clip and screw to the working one. Perhaps you can identify the problem. You can run a finger nail or something through the thread to see if the screw is too long or if there is damage to the threads.

If it is marked "Asahi PENTAX Japan" it should be a genuine adapter.

05-12-2017, 06:01 PM   #9
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QuoteOriginally posted by Not a Number Quote
A few members have reported that the focus mark will align to the 12 o'clock position but the majority of the members that responded to the same question say their lenses line up to around the 11 o'clock position. I have three genuine adapters - one marked "PENTAX Japan" and two marked "PENTAX Philippines". All of my screwmount lenses will align to around the 11 o'clock position. All of these lenses except a Takumar 135mm line up to the 12 o'clock position on my Asahi Pentax Auto Bellows. The 135mm goes a touch past say to 12:15 o'clock. I speculated perhaps the "Asahi Pentax" branded adapters lined up to 12 o'clock but this doesn't seem to be the case. It may just be individual variation or perhaps only a few production runs of the adapter line up to center. Who knows?

It has been speculated that the reason for the offset was due to the overhang on the prism housing on K-mount bodies but the overhang on the early K-mount bodies rarely goes beyond the bayonet flange. Again, who knows?

You may want to reassemble the misbehaving adapter and compare the clip and screw to the working one. Perhaps you can identify the problem. You can run a finger nail or something through the thread to see if the screw is too long or if there is damage to the threads.

If it is marked "Asahi PENTAX Japan" it should be a genuine adapter.
Thanks again for the great level of help you've provided. Guess it's good to know one shouldn't expect the red focusing mark on the M42 Takumars to register straight up when using the adapter. It just looks a little "not quite right" which caused my initial concern as well as making me wonder if I might have caused the adapter issue by attempting to get that red line to 12 o'clock (as I remembered it appearing on my Spotmatics way back when ;-) But, heck, the bottom line is being able to use some classic M42 Takumar glass on the little ME Super, including knowing it will focus its full range.
Yes, from an analytical standpoint, I should at least attempt reassembly...assuming I can locate the clip that popped out and figure out how it goes back in - oddly, the tiny screw did not migrate to another dimension and I have it safely in a clear plastic bag.
Again, thanks - hope to use that 150/4 on the ME Super on first nice day - now that the Alien face hugger has been removed ;-)
05-13-2017, 12:11 AM   #10
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Real good to hear you got it sorted!
05-13-2017, 04:41 AM   #11
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I've bought and sold dozens of genuine m42 > K adapters over the years. In my experience, whatever the vintage, some of them do not allow the focusing scale to line up perfectly and others do. After a frustrating experience just like the OP I decided I had overtightened my lens trying to line things up, so now I just finger-tighten and let it be.
06-20-2019, 09:07 PM - 1 Like   #12
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QuoteOriginally posted by MarkJerling Quote
It's hard to get a grip on the adapter. Best way, I find, is to use a rear K-mount lens cap to "grip" the adapter and then you'll have more holding power to unscrew the lens from the adapter.
Absolutely f'n brilliant! I know I'm coming in after the fact and with a slightly different problem, but this coupled with some judiciously applied force saved the day.

I recently scored a Fish-Eye Takumar 17mm that had been "converted" to Canon EF mount. I looked at the photos and (thought I had) determined that it only had an M42 to EF adapter screwed on. The "conversion" had made it a relative bargain, so I took my shot, thinking I'd back the adapter off and use it M42-to-whatever. Well...it was mated up good and proper. As was discussed, it's hard to get purchase on the thin rim of the adapter, so I had decided that adhesive had been used. When I read the tip about using the rear cap in reverse, I took a strap wrench to the lens and to the cap and BINGO! I now have a freed lens and a spare EF adapter.

Many thanks to the contributors!
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