Cosina MC

**apisto** · 09-30-2009, 02:48 PM

I recently bought 2 Cosina lenses at my local camera shop for $17.50 each.

200/4 PK
28-70/2.8 PK/A

I took the 28-70 back because it was not mounting smooth on my K20D, so I did not want to take any chances. (Although it did mount okay on the one in the K20D in the store.)

I have not had a chance to play with the 200/4 yet.

EDIT: Upon reflection I think the 28-70 was F4.

Last edited by apisto; 09-30-2009 at 03:11 PM.

k81 · 01-26-2011, 10:13 PM

Can anyone tell me if the Cosina 24mm 2.8 is any good?

m42man · 01-27-2011, 02:02 AM

Originally posted by Miserere

Stiff and jerky seems like a great way to describe it, Abraham

I think this must be a common trait for Cosinon lenses of that era, as both my 50/2s have stiff and jerky focusing. Almost as if the lubrication has dried out (which it has, no doubt!).

fb_penpho · 01-27-2011, 10:35 AM - **1 Like**

I submitted an entry that should help someone who wishes to lubricate cosinon lens. Cosina seem to have a common method of construction.

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/31353-off-bran...ml#post1175472

m42man · 01-28-2011, 01:57 AM

Thanks for that, fb_penpho! You're right, they're very decent lenses optically, and definitely worth fixing.

By the way, I have a suspicion that lenses from that era generally used Philips screws, as opposed to the more modern cross-head types. Philips screwdrivers have a more rounded tip than the modern types, so this may account for the need to grind down the tip.

Now, can anyone recommend a suitable lubricant?!

**Douglas_of_Sweden** · 01-28-2011, 05:43 AM

All Cosinon are just K mount. Some labelled Cosina MC are KA mount. I have the same 28mm f2.8 in KA. Plastic but good optically. Was acutally my first K-mount 28mm since long ago. I also have a Cosina 20mm f3.8 in KA mount, which is also a surprisingly good lens, but in difference to the 28mm, the 20mm is all metal and very good construction. I think the same 20mm was also sold with the Vivitar label. The Cosina 24mm with KA mount appear under several labels, Vivitar, Exakta (marketed in the UK), Miranda etc.

andiesam2004 · 03-15-2011, 09:27 AM

I have a Cosina 28mm F2.8MC Macro however it does not fit my Pentax Kx. I too was of the opinion that all Cosina are K mount. I can't understand why it does not fit.

RioRico · 03-16-2011, 07:14 AM

Originally posted by andiesam2004

I have a Cosina 28mm F2.8MC Macro however it does not fit my Pentax Kx. I too was of the opinion that all Cosina are K mount. I can't understand why it does not fit.

Cosina made lenses in various mounts. I know they made lenses for the Pentacon-B bayonet mount, which is somewhat similar to the PK. What does your lens base look like? Are you sure it's supposed to be for PK? Does it have PK inscribed on it? Have you compared it to pictures of various lens bases? Could you post a pcture of it so we could maybe identify it?

andiesam2004 · 03-16-2011, 11:31 PM

Originally posted by RioRico

Cosina made lenses in various mounts. I know they made lenses for the Pentacon-B bayonet mount, which is somewhat similar to the PK. What does your lens base look like? Are you sure it's supposed to be for PK? Does it have PK inscribed on it? Have you compared it to pictures of various lens bases? Could you post a pcture of it so we could maybe identify it?

Here are a few pictures of the Mount. I am not sure of the type of mount because it is not written on it. When I bought it on eBay I was told it was a K mount. Thanks for your help.

RioRico · 03-17-2011, 12:13 AM

Originally posted by andiesam2004

Here are a few pictures of the Mount. I am not sure of the type of mount because it is not written on it. When I bought it on eBay I was told it was a K mount. Thanks for your help.

Yes, that is a Pentacon Bayonet (PB) mount, not Pentax PK. Those three button contacts are the giveaway. The PB register (flange focal distance) is 44.4mm. The PK and M42 register is longer at 45.46mm. Putting short-register lenses onto long-register cameras always loses infinity focus. It is possible to modify the lens base slightly, to make it fit a PK mount. But it will only be usable for close-ups. I just received a PB-mount lens, a Prakticar 50/2.4, and when I jam it onto a Pentax SLR, furthest focus is only about 24in / 60cm.

What to do with your lens? Return it if you can. Or buy a Canon, Sony, or m4/3 camera to mount it on. Or even a Pentacon Bayonet film camera -- they are pretty cheap now. But I would return it as NOT AS DESCRIBED because it is NOT a Pentax-able lens. Good luck!

andiesam2004 · 03-18-2011, 03:15 PM

Originally posted by RioRico

Yes, that is a Pentacon Bayonet (PB) mount, not Pentax PK. Those three button contacts are the giveaway. The PB register (flange focal distance) is 44.4mm. The PK and M42 register is longer at 45.46mm. Putting short-register lenses onto long-register cameras always loses infinity focus. It is possible to modify the lens base slightly, to make it fit a PK mount. But it will only be usable for close-ups. I just received a PB-mount lens, a Prakticar 50/2.4, and when I jam it onto a Pentax SLR, furthest focus is only about 24in / 60cm.

What to do with your lens? Return it if you can. Or buy a Canon, Sony, or m4/3 camera to mount it on. Or even a Pentacon Bayonet film camera -- they are pretty cheap now. But I would return it as NOT AS DESCRIBED because it is NOT a Pentax-able lens. Good luck!

Thanks a lot. I tried two Camera stores in the New York are and neither of them could identify the mount. I will return it. Thanks again.

01-27-2011, 10:35 AM - 1 Like	#19
fb_penpho Senior Member Join Date: Jul 2009 Location: London Photos: Gallery Posts: 212	How to lubricate I submitted an entry that should help someone who wishes to lubricate cosinon lens. Cosina seem to have a common method of construction. https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/31353-off-bran...ml#post1175472

03-16-2011, 11:31 PM	#24
andiesam2004 New Member Join Date: Mar 2011 Location: New Brunswick, NJ Posts: 5	Originally posted by RioRico Cosina made lenses in various mounts. I know they made lenses for the Pentacon-B bayonet mount, which is somewhat similar to the PK. What does your lens base look like? Are you sure it's supposed to be for PK? Does it have PK inscribed on it? Have you compared it to pictures of various lens bases? Could you post a pcture of it so we could maybe identify it? Here are a few pictures of the Mount. I am not sure of the type of mount because it is not written on it. When I bought it on eBay I was told it was a K mount. Thanks for your help. Attached Images

03-17-2011, 12:13 AM	#25
RioRico Veteran Member Join Date: Jun 2008 Location: Limbo, California Posts: 11,263	Originally posted by andiesam2004 Here are a few pictures of the Mount. I am not sure of the type of mount because it is not written on it. When I bought it on eBay I was told it was a K mount. Thanks for your help. Yes, that is a Pentacon Bayonet (PB) mount, not Pentax PK. Those three button contacts are the giveaway. The PB register (flange focal distance) is 44.4mm. The PK and M42 register is longer at 45.46mm. Putting short-register lenses onto long-register cameras always loses infinity focus. It is possible to modify the lens base slightly, to make it fit a PK mount. But it will only be usable for close-ups. I just received a PB-mount lens, a Prakticar 50/2.4, and when I jam it onto a Pentax SLR, furthest focus is only about 24in / 60cm. What to do with your lens? Return it if you can. Or buy a Canon, Sony, or m4/3 camera to mount it on. Or even a Pentacon Bayonet film camera -- they are pretty cheap now. But I would return it as NOT AS DESCRIBED because it is NOT a Pentax-able lens. Good luck! Last edited by RioRico; 03-17-2011 at 12:24 AM.

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09-30-2009, 02:48 PM	#16
apisto Loyal Site Supporter Join Date: Jul 2009 Location: Minnesota Posts: 588	I recently bought 2 Cosina lenses at my local camera shop for $17.50 each. 200/4 PK 28-70/2.8 PK/A I took the 28-70 back because it was not mounting smooth on my K20D, so I did not want to take any chances. (Although it did mount okay on the one in the K20D in the store.) I have not had a chance to play with the 200/4 yet. EDIT: Upon reflection I think the 28-70 was F4. Last edited by apisto; 09-30-2009 at 03:11 PM.

01-26-2011, 10:13 PM	#17
k81 Inactive Account Join Date: Jan 2011 Location: Western Australia Posts: 4	Can anyone tell me if the Cosina 24mm 2.8 is any good?

01-27-2011, 02:02 AM	#18
m42man Veteran Member Join Date: Jan 2010 Location: Southern England Posts: 623	Originally posted by Miserere Stiff and jerky seems like a great way to describe it, Abraham I think this must be a common trait for Cosinon lenses of that era, as both my 50/2s have stiff and jerky focusing. Almost as if the lubrication has dried out (which it has, no doubt!).

01-28-2011, 01:57 AM	#20
m42man Veteran Member Join Date: Jan 2010 Location: Southern England Posts: 623	Thanks for that, fb_penpho! You're right, they're very decent lenses optically, and definitely worth fixing. By the way, I have a suspicion that lenses from that era generally used Philips screws, as opposed to the more modern cross-head types. Philips screwdrivers have a more rounded tip than the modern types, so this may account for the need to grind down the tip. Now, can anyone recommend a suitable lubricant?!

01-28-2011, 05:43 AM	#21
Douglas_of_Sweden Site Supporter Join Date: Apr 2008 Location: Stockholm Photos: Gallery Posts: 3,374	All Cosinon are just K mount. Some labelled Cosina MC are KA mount. I have the same 28mm f2.8 in KA. Plastic but good optically. Was acutally my first K-mount 28mm since long ago. I also have a Cosina 20mm f3.8 in KA mount, which is also a surprisingly good lens, but in difference to the 28mm, the 20mm is all metal and very good construction. I think the same 20mm was also sold with the Vivitar label. The Cosina 24mm with KA mount appear under several labels, Vivitar, Exakta (marketed in the UK), Miranda etc.

03-15-2011, 09:27 AM	#22
andiesam2004 New Member Join Date: Mar 2011 Location: New Brunswick, NJ Posts: 5	I have a Cosina 28mm F2.8MC Macro however it does not fit my Pentax Kx. I too was of the opinion that all Cosina are K mount. I can't understand why it does not fit.

03-16-2011, 07:14 AM	#23
RioRico Veteran Member Join Date: Jun 2008 Location: Limbo, California Posts: 11,263	Originally posted by andiesam2004 I have a Cosina 28mm F2.8MC Macro however it does not fit my Pentax Kx. I too was of the opinion that all Cosina are K mount. I can't understand why it does not fit. Cosina made lenses in various mounts. I know they made lenses for the Pentacon-B bayonet mount, which is somewhat similar to the PK. What does your lens base look like? Are you sure it's supposed to be for PK? Does it have PK inscribed on it? Have you compared it to pictures of various lens bases? Could you post a pcture of it so we could maybe identify it?

03-18-2011, 03:15 PM	#26
andiesam2004 New Member Join Date: Mar 2011 Location: New Brunswick, NJ Posts: 5	Originally posted by RioRico Yes, that is a Pentacon Bayonet (PB) mount, not Pentax PK. Those three button contacts are the giveaway. The PB register (flange focal distance) is 44.4mm. The PK and M42 register is longer at 45.46mm. Putting short-register lenses onto long-register cameras always loses infinity focus. It is possible to modify the lens base slightly, to make it fit a PK mount. But it will only be usable for close-ups. I just received a PB-mount lens, a Prakticar 50/2.4, and when I jam it onto a Pentax SLR, furthest focus is only about 24in / 60cm. What to do with your lens? Return it if you can. Or buy a Canon, Sony, or m4/3 camera to mount it on. Or even a Pentacon Bayonet film camera -- they are pretty cheap now. But I would return it as NOT AS DESCRIBED because it is NOT a Pentax-able lens. Good luck! Thanks a lot. I tried two Camera stores in the New York are and neither of them could identify the mount. I will return it. Thanks again.