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09-30-2009, 02:48 PM   #16
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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
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Can anyone tell me if the Cosina 24mm 2.8 is any good?
01-27-2011, 02:02 AM   #18
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QuoteOriginally posted by Miserere Quote
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!).
01-27-2011, 10:35 AM - 1 Like   #19
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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

01-28-2011, 01:57 AM   #20
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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
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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
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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
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QuoteOriginally posted by andiesam2004 Quote
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?

03-16-2011, 11:31 PM   #24
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QuoteOriginally posted by RioRico Quote
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.
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03-17-2011, 12:13 AM   #25
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QuoteOriginally posted by andiesam2004 Quote
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.
03-18-2011, 03:15 PM   #26
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QuoteOriginally posted by RioRico Quote
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.
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