Pentax MX with M42 Adapter - Cannot fit 21mm lens

MarieDJ · 08-25-2011, 09:10 PM

Hello everyone!

I have an MX fitted with a genuine pentax M42 adapter to use those great takumar lenses. However, I just acquired a Mamiya Sekor 21mm lens that will not screw in all the way...and I am unsure as to why. Any help would be greatly appreciated.

titrisol · 08-26-2011, 01:10 AM

I saw your photo on flickr.
If you have a screw mount camera test the lens there; maybe the threads were damaged at some point.
Otherwise, some Mamiya lenses used to sit at an angle compared to takumars.

Wheatfield · 08-26-2011, 06:58 AM

There may be a small pin sticking out of the back of the lens that is fouling the mount. I recall a customer of mine having this problem with a Mamiya lens.

MarieDJ · 08-26-2011, 07:53 AM

I will test it out - my Spotmatics are currently in Eric Hendrickson's hands getting a much needed overhaul. As soon as I get them back I will see.

stevebrot · 08-26-2011, 09:03 AM

What series Mamiya Sekor lens is it? The SX series M42 lenses had extra coupling hardware that may be the source of the problem.

Steve

MarieDJ · 08-26-2011, 11:41 AM

The lens does say SX - I am attaching some pics...

titrisol · 08-26-2011, 02:14 PM

looks very good!!
However the rear element seems to be quite large and may touch the mirror and thus prevent it from screwing in
just a hunch... can you try it in the adaptor out of the camera

stevebrot · 08-26-2011, 03:55 PM

Originally posted by MarieDJ

The lens does say SX - I am attaching some pics...

See the pin on the left? That is probably your problem. As suggested above, you might try putting the adapter on the lens off-camera as a test.

You might also try Google since this is a known compatability issue with the SX lenses on non-SX compatible bodies. Here is a link to a page that details the surgery to make your lens usable with other than SX cameras:

Mamiya Sx lens auto diaphragm pin modification and adapting.

Steve

MarieDJ · 08-27-2011, 05:32 AM

Thank you for the link. I had no idea what I was getting myself into when purchasing this lens! I am not too much of a handy person when it comes to DIY, but do you think Eric Hendrickson might be able to mod it for me? I will ask him, but just wondering if he does that normally?

Thank you so much for resolving this issue. At least I know what was causing the issue.

Blue · 08-27-2011, 06:13 AM

Given the quirkiness of the SX series lenses, they are still excellent performers. As far as Eric modifying it for you, email him along with the above pic. I suspect he would. He also needs to deal with the aperture pin in addition to the other pin because it doesn't have an A-M switch which means it is in Auto all the time. It will need to be in manual to use on K-mount film and digital bodies. That over hang the aperture ring does has given me problems before on The Sekor 28mm SX.

08-25-2011, 09:10 PM	#1
MarieDJ Guest	Pentax MX with M42 Adapter - Cannot fit 21mm lens Hello everyone! I have an MX fitted with a genuine pentax M42 adapter to use those great takumar lenses. However, I just acquired a Mamiya Sekor 21mm lens that will not screw in all the way...and I am unsure as to why. Any help would be greatly appreciated.

08-26-2011, 11:41 AM	#6
MarieDJ Guest	The lens does say SX - I am attaching some pics... Attached Images

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08-26-2011, 01:10 AM	#2
titrisol Pentaxian Join Date: Dec 2007 Location: In the most populated state... state of denial Photos: Gallery \| Albums Posts: 1,852	I saw your photo on flickr. If you have a screw mount camera test the lens there; maybe the threads were damaged at some point. Otherwise, some Mamiya lenses used to sit at an angle compared to takumars.

08-26-2011, 06:58 AM	#3
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,981	There may be a small pin sticking out of the back of the lens that is fouling the mount. I recall a customer of mine having this problem with a Mamiya lens.

08-26-2011, 07:53 AM	#4
MarieDJ Guest	I will test it out - my Spotmatics are currently in Eric Hendrickson's hands getting a much needed overhaul. As soon as I get them back I will see.

08-26-2011, 09:03 AM	#5
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	What series Mamiya Sekor lens is it? The SX series M42 lenses had extra coupling hardware that may be the source of the problem. Steve

08-26-2011, 02:14 PM	#7
titrisol Pentaxian Join Date: Dec 2007 Location: In the most populated state... state of denial Photos: Gallery \| Albums Posts: 1,852	looks very good!! However the rear element seems to be quite large and may touch the mirror and thus prevent it from screwing in just a hunch... can you try it in the adaptor out of the camera

08-26-2011, 03:55 PM	#8
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by MarieDJ The lens does say SX - I am attaching some pics... See the pin on the left? That is probably your problem. As suggested above, you might try putting the adapter on the lens off-camera as a test. You might also try Google since this is a known compatability issue with the SX lenses on non-SX compatible bodies. Here is a link to a page that details the surgery to make your lens usable with other than SX cameras: Mamiya Sx lens auto diaphragm pin modification and adapting. Steve

08-27-2011, 05:32 AM	#9
MarieDJ Guest	Thank you for the link. I had no idea what I was getting myself into when purchasing this lens! I am not too much of a handy person when it comes to DIY, but do you think Eric Hendrickson might be able to mod it for me? I will ask him, but just wondering if he does that normally? Thank you so much for resolving this issue. At least I know what was causing the issue.

08-27-2011, 06:13 AM	#10
Blue Moderator Site Supporter Join Date: Jun 2008 Location: Florida Hill Country Photos: Gallery \| Albums Posts: 17,377	Given the quirkiness of the SX series lenses, they are still excellent performers. As far as Eric modifying it for you, email him along with the above pic. I suspect he would. He also needs to deal with the aperture pin in addition to the other pin because it doesn't have an A-M switch which means it is in Auto all the time. It will need to be in manual to use on K-mount film and digital bodies. That over hang the aperture ring does has given me problems before on The Sekor 28mm SX.