Win a Pentax Limited Lens: Raffle Now Live!

causey · 12-22-2010, 04:01 PM

I recently got a SMC Takumar 28mm 3.5, and it has a kind of metal square protrusion on the mount which makes it harder to mount it... (It looks like the one in the picture.) It scratches the camera's mount so hard (the lens looks absolutely new) that I'm afraid it might damage the camera. In any case, it goes about 1.5mm above the level of the adapter... Is my worry justified? Should I try to remove it?

Thank you!

Attached Images

Last edited by causey; 12-22-2010 at 04:32 PM.

causey · 12-22-2010, 04:30 PM

Answering my own question... The protrusion cannot scratch the camera's mount, since it does not fall on it. I wonder however why there's so much friction with this lens when mounting it... It's been much easier with other m42 lenses...

Mike Cash · 12-22-2010, 04:34 PM

Probably some damage to the threads. Take a close look at them and you may find it.

The square bit is part of the open-aperture metering apparatus for using with a certain few models of Spotmatics. Irrelevant on digital.

macTak · 12-22-2010, 05:57 PM

Originally posted by Mike Cash

Probably some damage to the threads. Take a close look at them and you may find it.

The square bit is part of the open-aperture metering apparatus for using with a certain few models of Spotmatics. Irrelevant on digital.

What he said. I'll just add that the threads may just be dirty/have some gunk on/in them, so give them a cleaning and then check to see if they are indeed damaged.

causey · 12-22-2010, 06:14 PM

You mean, the lens's threads? (I can't see how the square protrusion could affect those.) Or the internal threads of the camera (in front of the mirror)? (These seem to be fine, although I have no idea what use they have.)

kxr4trids · 12-22-2010, 06:23 PM

Are you putting the adapter on the lens and then trying to fit it to the body? Try putting the adapter ring in the camera and noting if it is slightly recessed from the face of the mount. If this is the case, you may need to shim the adapter on the lens to the difference of this depth. I ran into this problem with the Chinese adapter rings. They *look* the same, but the tolerances are crap.

causey · 12-22-2010, 06:35 PM

Yes, the friction was due to the adapter (Chinese clone)--I have a second adapter, whose action is much smoother.
On the other hand, the protrusion did touch the internal threads of the camera, but only barely. I wonder what these threads are for.

Mike Cash · 12-23-2010, 05:00 AM

The thread on the lens are to hold it to the adapter. The threads on the adapter are to hold the lens. Forget about the square protrusion; it is supposed to be there. If it hits the threads on your adapter then the problem is a poorly made adapter.

The adapter being slightly recessed from the face of the camera is also irrelevant; it affects nothing. It won't prevent the lens from going snug against the camera body, which is where it is supposed to be.

causey · 12-23-2010, 07:22 AM

Thank you all - no threads are affected. I changed the adapter, and the new one doesn't require so much force to mount or dismount the lens. Everything's fine. I was afraid the protrusion might touch something in the camera (more specifically, something that looks like threads inside the camera), but apparently it can't.

12-22-2010, 04:01 PM	#1
causey Veteran Member Join Date: Feb 2009 Location: Arlington, VA Photos: Albums Posts: 3,757	Square protrusion on a Tak's mount? I recently got a SMC Takumar 28mm 3.5, and it has a kind of metal square protrusion on the mount which makes it harder to mount it... (It looks like the one in the picture.) It scratches the camera's mount so hard (the lens looks absolutely new) that I'm afraid it might damage the camera. In any case, it goes about 1.5mm above the level of the adapter... Is my worry justified? Should I try to remove it? Thank you! Attached Images Last edited by causey; 12-22-2010 at 04:32 PM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Kennett Square, Pa	Dave-Kr	Welcomes and Introductions	2	10-23-2010 03:34 PM
4 square	TGregory	Monthly Photo Contests	0	08-03-2009 09:38 AM
My first Tak's on the way!	SCguy	Pentax SLR Lens Discussion	6	07-27-2009 06:30 PM
For Sale - Sold: Pentax Screw mount lenses. Tak's Soligor, Tamron, Mamiya	benjamin59	Sold Items	30	02-07-2009 12:56 PM

12-22-2010, 04:30 PM	#2
causey Veteran Member Join Date: Feb 2009 Location: Arlington, VA Photos: Albums Posts: 3,757 Original Poster	Answering my own question... The protrusion cannot scratch the camera's mount, since it does not fall on it. I wonder however why there's so much friction with this lens when mounting it... It's been much easier with other m42 lenses...

12-22-2010, 04:34 PM	#3
Mike Cash Veteran Member Join Date: Jan 2007 Location: Japan Photos: Gallery Posts: 6,950	Probably some damage to the threads. Take a close look at them and you may find it. The square bit is part of the open-aperture metering apparatus for using with a certain few models of Spotmatics. Irrelevant on digital.

12-22-2010, 05:57 PM	#4
macTak Veteran Member Join Date: Apr 2010 Photos: Gallery Posts: 759	Originally posted by Mike Cash Probably some damage to the threads. Take a close look at them and you may find it. The square bit is part of the open-aperture metering apparatus for using with a certain few models of Spotmatics. Irrelevant on digital. What he said. I'll just add that the threads may just be dirty/have some gunk on/in them, so give them a cleaning and then check to see if they are indeed damaged.

12-22-2010, 06:14 PM	#5
causey Veteran Member Join Date: Feb 2009 Location: Arlington, VA Photos: Albums Posts: 3,757 Original Poster	You mean, the lens's threads? (I can't see how the square protrusion could affect those.) Or the internal threads of the camera (in front of the mirror)? (These seem to be fine, although I have no idea what use they have.)

12-22-2010, 06:23 PM	#6
kxr4trids Senior Member Join Date: Mar 2010 Location: VA Photos: Albums Posts: 227	Are you putting the adapter on the lens and then trying to fit it to the body? Try putting the adapter ring in the camera and noting if it is slightly recessed from the face of the mount. If this is the case, you may need to shim the adapter on the lens to the difference of this depth. I ran into this problem with the Chinese adapter rings. They look the same, but the tolerances are crap.

12-22-2010, 06:35 PM	#7
causey Veteran Member Join Date: Feb 2009 Location: Arlington, VA Photos: Albums Posts: 3,757 Original Poster	Yes, the friction was due to the adapter (Chinese clone)--I have a second adapter, whose action is much smoother. On the other hand, the protrusion did touch the internal threads of the camera, but only barely. I wonder what these threads are for.

12-23-2010, 05:00 AM	#8
Mike Cash Veteran Member Join Date: Jan 2007 Location: Japan Photos: Gallery Posts: 6,950	The thread on the lens are to hold it to the adapter. The threads on the adapter are to hold the lens. Forget about the square protrusion; it is supposed to be there. If it hits the threads on your adapter then the problem is a poorly made adapter. The adapter being slightly recessed from the face of the camera is also irrelevant; it affects nothing. It won't prevent the lens from going snug against the camera body, which is where it is supposed to be.

12-23-2010, 07:22 AM	#9
causey Veteran Member Join Date: Feb 2009 Location: Arlington, VA Photos: Albums Posts: 3,757 Original Poster	Thank you all - no threads are affected. I changed the adapter, and the new one doesn't require so much force to mount or dismount the lens. Everything's fine. I was afraid the protrusion might touch something in the camera (more specifically, something that looks like threads inside the camera), but apparently it can't.

Square protrusion on a Tak's mount?

Win a Pentax Limited Lens: Raffle Now Live!