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Why a Cosina 40mm keeps the aperture open when on camera?
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Posted: Sun Aug 07, 2016 3:56 pm
Post subject: Why a Cosina 40mm keeps the aperture open when on camera?
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Posted: Sun Aug 07, 2016 3:56 pm
Post subject: Why a Cosina 40mm keeps the aperture open when on camera?
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Hi,
I got a copy of Cosina 40mm pancake for Pentax.
http://www.pentaxforums.com/userreviews/cosina-cosinon-40mm-f2-5-auto-mc.html

When not on cam, it looks like everything works fine.
When mounted on a Pentax k5-2, it
keeps the aperture always open, whatever you do.

Well, it is always possible to think of course, but lazy as I am, I decided to ask first... what did I wrong?


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Posted: Sun Aug 07, 2016 4:08 pm
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Posted: Sun Aug 07, 2016 4:08 pm
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I think its a PK mount, not PK/A
So it can only be used in M mode on Pentax DSLR.
Any other mide and it will not stop down.
Try it in M, set to smaller aperture and check if it stops down.


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Posted: Mon Aug 08, 2016 6:57 am
Post subject: Re: Why a Cosina 40mm keeps the aperture open when on camera
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Post
Posted: Mon Aug 08, 2016 6:57 am
Post subject: Re: Why a Cosina 40mm keeps the aperture open when on camera
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mesinik wrote:
Hi,
I got a copy of Cosina 40mm pancake for Pentax.
http://www.pentaxforums.com/userreviews/cosina-cosinon-40mm-f2-5-auto-mc.html

When not on cam, it looks like everything works fine.
When mounted on a Pentax k5-2, it
keeps the aperture always open, whatever you do.

Well, it is always possible to think of course, but lazy as I am, I decided to ask first... what did I wrong?

Did you enable the green button function? At least older Pentax DSLR cameras worked that way. The other option could be too long aperture lever on the lens. Just guessing.
Try it also on analog Pentax.


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Posted: Mon Aug 08, 2016 1:14 pm
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Posted: Mon Aug 08, 2016 1:14 pm
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http://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/110658-using-manual-lenses-m42-screwmount-m-k-pentax-dslrs-f.html

http://www.tremyfoel.co.uk/photography/pentax/KM-M42pentax.html
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