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05-07-2018, 01:34 PM   #1
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Pentax K-1 AF Problem

Hello everyone and sorry for the trouble. I open this forum because you can not find answers to my problems.
I am in possession of a Pentax K1
The problem is that my 28-105 works perfectly, even the AF.
Instead the tamron 70-300 that I have when I try to focus automatically, the ring always scrolls to the end (beyond infinity) and never puts anything into focus. I thought the lens was broken, so I decided to change it from Amazon. Result: nothing has changed. I do not understand if the problem is my k-1 that with 28-105 works perfectly, or the goal. Thanks in advance for the answers.

05-07-2018, 01:50 PM   #2
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Is your Tamron 70-300 set in Macro mode? If so, it might not be able to focus on anything that's too far away.
(You'd have to be zoomed in quite a bit and flip the switch, so probably not.)
05-07-2018, 05:20 PM   #3
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QuoteOriginally posted by fabiosposato Quote
Hello everyone and sorry for the trouble. I open this forum because you can not find answers to my problems.
I am in possession of a Pentax K1
The problem is that my 28-105 works perfectly, even the AF.
Instead the tamron 70-300 that I have when I try to focus automatically, the ring always scrolls to the end (beyond infinity) and never puts anything into focus. I thought the lens was broken, so I decided to change it from Amazon. Result: nothing has changed. I do not understand if the problem is my k-1 that with 28-105 works perfectly, or the goal. Thanks in advance for the answers.
Is the AF lever properly engaged? Does your K-1 work fine with other screwdrive lenses?

Can the tamron manually be focused correctly? If not then there's an issue with the lens regardless.

Adam
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05-08-2018, 04:40 AM   #4
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QuoteOriginally posted by Heebie Quote
Is your Tamron 70-300 set in Macro mode? If so, it might not be able to focus on anything that's too far away.
(You'd have to be zoomed in quite a bit and flip the switch, so probably not.)
Heebie it does not work both in normal and in macro mode

05-08-2018, 04:42 AM   #5
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QuoteOriginally posted by Adam Quote
Is the AF lever properly engaged? Does your K-1 work fine with other screwdrive lenses?

Can the tamron manually be focused correctly? If not then there's an issue with the lens regardless.
Adam it work perfectly with my Pentax 28-105, and the tamron work perfectly in manual focus
05-08-2018, 09:50 AM   #6
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QuoteOriginally posted by fabiosposato Quote
Adam it work perfectly with my Pentax 28-105, and the tamron work perfectly in manual focus
The 28-105mm (assuming we're talking about the D FA lens) is not screwdrive. My suspicion is that there's an issue with the screwdrive mechanism on your camera.

Does the drive shaft look OK on both the camera and the lens?

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05-08-2018, 10:38 AM   #7
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QuoteOriginally posted by Adam Quote
The 28-105mm (assuming we're talking about the D FA lens) is not screwdrive. My suspicion is that there's an issue with the screwdrive mechanism on your camera.

Does the drive shaft look OK on both the camera and the lens?
Yes Adam, my 28-105 is the d fa. But how can I see if there are problems with my drive shaft? What is the drive shaft. Sorry but i’m Italian and for me is difficult to understand the part of the camera and translate it
05-08-2018, 04:20 PM   #8
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It's labeled vi in this image:



It should be perfectly flush with the lens mount.

There's a corresponding driveshaft on the camera mount, which should protrude slightly.

When you mount the lens on the camera (and maybe wiggle a bit if needed), the camera shaft should engage with the one in the lens, and turn the focusing mechanism when needed.


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05-09-2018, 05:20 AM   #9
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Now I link the photos of the drive shaft of the camera and lens. For me all is ok,but i’m A beginner.
Thanks
Link:Update your browser to use Google Drive - Google Drive Help
05-13-2018, 01:49 AM   #10
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QuoteOriginally posted by fabiosposato Quote
Hello everyone and sorry for the trouble. I open this forum because you can not find answers to my problems.
I am in possession of a Pentax K1
The problem is that my 28-105 works perfectly, even the AF.
Instead the tamron 70-300 that I have when I try to focus automatically, the ring always scrolls to the end (beyond infinity) and never puts anything into focus. I thought the lens was broken, so I decided to change it from Amazon. Result: nothing has changed. I do not understand if the problem is my k-1 that with 28-105 works perfectly, or the goal. Thanks in advance for the answers.
Perplexing.

When you try to use autofocus with the Tamron 70-300, does the focus ring move? (Looks like it does from the original question, just want to be sure).

If the focus ring does turn during autofocus, it would seem to me that the screw-drive in the body is working fine.

If you switch to manual focus (MF/AF switch on the K-1 body) and turn the focus ring on the Tamron by hand, does that bring the subject into focus?
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