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03-23-2019, 04:08 PM   #1
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Autofocus problem with K-70

I just got my new K-70 and I find that autofocus doesn't work with my Pentax DA 1:4-5.8 55-300mm ED lens. It works fine with the Pentax DA 18-55 II. Anything I can do about this, or am I just going to have to bite the bullet? Thanks.

03-23-2019, 04:15 PM - 1 Like   #2
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QuoteOriginally posted by David82 Quote
I just got my new K-70 and I find that autofocus doesn't work with my Pentax DA 1:4-5.8 55-300mm ED lens. It works fine with the Pentax DA 18-55 II. Anything I can do about this, or am I just going to have to bite the bullet? Thanks.
What exact issue are you experiencing? Does it hunt back and forth, or not operate at all?

If it's the latter, then check to see if cleaning the contacts on the lens would help. If it's the former, try again in brighter ambient light.

Adam
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03-24-2019, 03:16 PM   #3
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It doesn't operate at all, and cleaning didn't help.
03-24-2019, 03:52 PM   #4
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QuoteOriginally posted by David82 Quote
It doesn't operate at all, and cleaning didn't help.
Did the 55-300 work on your previous camera or is it new too? If new, request a replacement from the vendor.


Steve

03-24-2019, 05:50 PM   #5
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It worked perfectly with a K-200D.

David
03-24-2019, 09:39 PM   #6
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QuoteOriginally posted by David82 Quote
It worked perfectly with a K-200D.

David
OK...with the 55-300 on your K-70 and the AF/MF switch turned to AF, turn the camera on. Does it say AF, AF.A, AF.S, or AF.C on the rear LCD? If not, does it have an f-number for the aperture setting on the rear LCD? Repeat with your 18-50.

If the answer to either first question is NO, the body was not able to identify that an auto-focus lens is mounted. If the answer to both questions is NO, the body was not able to determine that a lens with mount contacts is mounted. If this happens with both lenses, there might be a problem with the body. If only one of the two lenses, the problem is probably with the lens.

Even if it appears that the body may be at fault, now is a good time to take Adam's advice and clean the contacts on the body and both lenses. This is best done with a clean dry microfibre cloth and a gentle scrubbing motion on both the contacts and the mount face. The intent is to remove any soil or greasy material that may have collected on the contact surfaces. Pay particular attention to the contacts at the positions labeled "A" and "V" in the illustration below. The "A" contact is inset on the body side, making it a little more difficult.



It is the "A" contact that tells the body that a lens with contacts is mounted and the "V" contact that identifies it as an AF lens.


Steve
03-25-2019, 07:37 PM   #7
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Well, I don't know what to make of this. When I turned the K-70 on with the 55-300, it said MF, but then I turned it from 55 to higher, and it switched to AF.A and worked fine. I turned it off and on several times, and it randomly switches back and forth between MF and AF.A, though it mostly stays in autofocus. Maybe it was yesterday's cleaning. I guess I'll just have to keep working on that.

Thanks for the help.
03-25-2019, 08:48 PM   #8
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QuoteOriginally posted by David82 Quote
Thanks for the help.
Our pleasure! I'm glad you got some clarity of this and at least a starting point in figuring out what is going on.


Steve

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