Lens mount question

Fabien3d · 11-24-2015, 01:21 AM

Hello,

My father-in-law had a 28mm f/2.8 Rikenon lens in his Pentax gear bag. Apparently, this lens can't be mounted on a Pentax camera. Does anyone know which lens mount this is ?

Thanks !

alpheios · 11-24-2015, 04:12 AM

To me this looks like a M42 mount lens with a M42 to Pentax K mount adapter that has been screwed onto it the wrong way around.
Try to gently turn the outer silver part counterclockwise to unscrew the adapter.

pathdoc · 11-24-2015, 04:53 AM

My first thought was "Didn't Ricoh use the M42 mount before adopting the K mount?" But I think alpheios is correct. You should be able to unscrew it, and then it will be clear how the adapter flange fits into the camera and the lens screws back into the flange.

Interestingly, manuals for the MX and other early K mount cameras instruct mounting the adapter on the lens (the right way around!!) and putting the whole thing on the camera as if it were a K mount lens, then to take it off, unscrewing the lens and then dismounting the adapter (unless you want to use another screw-mount).

Reed · 11-24-2015, 06:41 AM

It looks like M-42 screw mount repair ring put on a normal M42 Ricoh lens. There should be also "canned ham" like handle to screw this on or off the mount, if the mount is not damaged you should be able to unscrew it easly just by bare hand.

bertwert · 11-24-2015, 08:20 AM

Looks like and M42 mount with adapter on backwards, as others have said.

jjdgti · 11-25-2015, 03:52 PM

Originally posted by bertwert

Looks like and M42 mount with adapter on backwards, as others have said.

That was my first impression.

y0chang · 11-25-2015, 09:10 PM

That pin might get stuck on dslr. Look up remove ricoh pin.

bertwert · 11-25-2015, 09:19 PM - **1 Like**

Originally posted by y0chang

That pin might get stuck on dslr. Look up remove ricoh pin.

This is not a ricoh pin there, it is the standard stop-down pin of an M42 lens, it in now way affects DSLR operation.

y0chang · 11-25-2015, 09:40 PM

Oh yeah...ricoh pin would only be on a bayonet mount....nvm...im not seeing straight

pathdoc · 11-26-2015, 05:07 AM

Originally posted by y0chang

That pin might get stuck on dslr. Look up remove ricoh pin.

That was my first thought too, that this was the Mother of All Ricoh Pins, but then I spotted the complete lack of aperture-coupling and stop-down levers and saw it for what it was.

Fabien3d · 11-26-2015, 04:28 PM

Hello,

Thanks for your replies ! I don't owe a "canned ham" so I used a twin screwdriver to remove it. Indeed, it is a m42 to PK mount adapter. I mounted the lens on my Pentax ME : it worked! But I had to unscrew the camera mount lens to remove the adapter... I will use my other adapter which doesn't require any tool to be removed :-)

How tricky this adapter is :-(

11-24-2015, 01:21 AM	#1
Fabien3d New Member Join Date: Nov 2015 Posts: 2	Lens mount question Hello, My father-in-law had a 28mm f/2.8 Rikenon lens in his Pentax gear bag. Apparently, this lens can't be mounted on a Pentax camera. Does anyone know which lens mount this is ? Thanks !

11-24-2015, 04:12 AM	#2
alpheios Pentaxian Join Date: Nov 2015 Location: Bremen Posts: 410	M42 with adaptor? To me this looks like a M42 mount lens with a M42 to Pentax K mount adapter that has been screwed onto it the wrong way around. Try to gently turn the outer silver part counterclockwise to unscrew the adapter. Last edited by alpheios; 11-24-2015 at 10:38 AM.

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11-24-2015, 04:53 AM	#3
pathdoc Pentaxian Join Date: Mar 2015 Photos: Gallery \| Albums Posts: 6,381	My first thought was "Didn't Ricoh use the M42 mount before adopting the K mount?" But I think alpheios is correct. You should be able to unscrew it, and then it will be clear how the adapter flange fits into the camera and the lens screws back into the flange. Interestingly, manuals for the MX and other early K mount cameras instruct mounting the adapter on the lens (the right way around!!) and putting the whole thing on the camera as if it were a K mount lens, then to take it off, unscrewing the lens and then dismounting the adapter (unless you want to use another screw-mount).

11-24-2015, 06:41 AM	#4
Reed Pentaxian Join Date: Mar 2015 Location: Warsaw Photos: Gallery Posts: 638	It looks like M-42 screw mount repair ring put on a normal M42 Ricoh lens. There should be also "canned ham" like handle to screw this on or off the mount, if the mount is not damaged you should be able to unscrew it easly just by bare hand.

11-24-2015, 08:20 AM	#5
bertwert Veteran Member Join Date: Jun 2015 Location: Golden, BC Posts: 15,173	Looks like and M42 mount with adapter on backwards, as others have said.

11-25-2015, 03:52 PM	#6
jjdgti Veteran Member Join Date: Jun 2008 Location: NJ Posts: 1,824	Originally posted by bertwert Looks like and M42 mount with adapter on backwards, as others have said. That was my first impression.

11-25-2015, 09:10 PM	#7
y0chang Veteran Member Join Date: Jan 2012 Location: United States Posts: 793	That pin might get stuck on dslr. Look up remove ricoh pin.

11-25-2015, 09:19 PM - 1 Like	#8
bertwert Veteran Member Join Date: Jun 2015 Location: Golden, BC Posts: 15,173	Originally posted by y0chang That pin might get stuck on dslr. Look up remove ricoh pin. This is not a ricoh pin there, it is the standard stop-down pin of an M42 lens, it in now way affects DSLR operation.

11-25-2015, 09:40 PM	#9
y0chang Veteran Member Join Date: Jan 2012 Location: United States Posts: 793	Oh yeah...ricoh pin would only be on a bayonet mount....nvm...im not seeing straight

11-26-2015, 05:07 AM	#10
pathdoc Pentaxian Join Date: Mar 2015 Photos: Gallery \| Albums Posts: 6,381	Originally posted by y0chang That pin might get stuck on dslr. Look up remove ricoh pin. That was my first thought too, that this was the Mother of All Ricoh Pins, but then I spotted the complete lack of aperture-coupling and stop-down levers and saw it for what it was.

11-26-2015, 04:28 PM	#11
Fabien3d New Member Join Date: Nov 2015 Posts: 2 Original Poster	Hello, Thanks for your replies ! I don't owe a "canned ham" so I used a twin screwdriver to remove it. Indeed, it is a m42 to PK mount adapter. I mounted the lens on my Pentax ME : it worked! But I had to unscrew the camera mount lens to remove the adapter... I will use my other adapter which doesn't require any tool to be removed :-) How tricky this adapter is :-(