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09-21-2009, 08:07 PM   #1
Pentaxian




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F 50 1.7 Losing AF

Hi all,

I've been having some trouble with my F 50 1.7 lens losing AF when mounted on my K10d. This usually happens after the lens has been functioning fine for a number of shots then MF appears in the viewfinder, metering is fine just no AF. If I turn the body off and on it asks for the lens' focal length so obviously the lens isn't communicating that info with the body either. Sometimes cleaning the lens' contact with an eraser and remounting is enough to get AF functioning again, other times no manner of cleaning will help and it's not until I've mounted a different lens and then remounted the F 50 will AF function.

All my other lens are 100% working on the K10d body so I'm positive that the issue is with this specific lens.

Any suggestions?

09-22-2009, 03:42 PM   #2
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I also have this lens but I don't have it long yet so I can't report any failures.
But if the contacts (on the lens' outside) aren't the problem something in the circuitry must be the reason. So it could be a faulty chip in the lens - it's almost 20 years old by now or simply a loose contact between mount and inner electronics.

So a lot of possibilities but no solutions from me.
09-23-2009, 05:27 PM   #3
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QuoteOriginally posted by Egg Salad Quote
I also have this lens but I don't have it long yet so I can't report any failures.
But if the contacts (on the lens' outside) aren't the problem something in the circuitry must be the reason. So it could be a faulty chip in the lens - it's almost 20 years old by now or simply a loose contact between mount and inner electronics.

So a lot of possibilities but no solutions from me.
I was afraid someone would say that I really love this lens.

Might give the contacts a thorough clean, tighten a few screws around the mount and failing that learn to manual focus.
09-24-2009, 07:32 AM   #4
axl
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hard to say and sorry to hear that.
I have the exact combination as you, and I've been using my F50 on K100D and GX20 too and it has yet to fail me.
Hope it works out for you

BR
Peter

09-24-2009, 07:36 AM   #5
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Sorry about your lens. I have a question though.

In another thread, someone is asking about the Tokina 70-200 ATX Pro not transmitting focal length to the camera. I thought I read that F lenses do not do this either. Is this true, or maybe true for some F lenses? I know I read something about this a while back.
09-24-2009, 07:43 AM   #6
axl
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QuoteOriginally posted by StephenMerola Quote
Sorry about your lens. I have a question though.

In another thread, someone is asking about the Tokina 70-200 ATX Pro not transmitting focal length to the camera. I thought I read that F lenses do not do this either. Is this true, or maybe true for some F lenses? I know I read something about this a while back.
not true with F50. It transmits the focal length flawlessly. I believe all F series are fitted with chip which transmits the focal length but I could be wrong here.

Peter
09-24-2009, 05:57 PM   #7
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QuoteOriginally posted by StephenMerola Quote
Sorry about your lens. I have a question though.

In another thread, someone is asking about the Tokina 70-200 ATX Pro not transmitting focal length to the camera. I thought I read that F lenses do not do this either. Is this true, or maybe true for some F lenses? I know I read something about this a while back.
When the lens is fully functional it transmits the focal lens to the camera, my F 28 2.8 also transmits the focal length to the camera.
09-24-2009, 05:59 PM   #8
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QuoteOriginally posted by axl Quote
hard to say and sorry to hear that.
I have the exact combination as you, and I've been using my F50 on K100D and GX20 too and it has yet to fail me.
Hope it works out for you

BR
Peter
At least there's nothing wrong with the glass and it's still metering fine, worse case scenario is I have to manual focus like it's an A lens.

09-25-2009, 12:07 AM   #9
axl
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QuoteOriginally posted by Mike L Quote
At least there's nothing wrong with the glass and it's still metering fine, worse case scenario is I have to manual focus like it's an A lens.
It's true that F50/1.7 is a great lens, so I think I'd keep it as A too but I love how fast it AFs. You should have it repaired.
I know there is a guy, I think he goes by the name of Eric, who will repair/clean/fix just about anything you send him (talking SLR glass here).

But I don't have contact on him.

Good luck

Peter
09-25-2009, 01:24 AM   #10
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Clean all the contacts with pure isopropyl alcohol, don't use eraser which is abasive. If that doesn't work, the mount might have to come off and have all contacts and springs cleaned.
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