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04-15-2021, 11:32 AM   #1
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K-1 Focusing Issues

All,

I had the shutter replaced in my K-1, and sent it back for re-work, to Precision. The reason I sent it back for re-work is that it seemed to have focusing issues with my Tamron A001 70-200mm.

I have received it back and have been taking some pictures with it. In bright light, all seems fine. However, in indoor light (with window lighting) at 10 feet from a still subject, zoomed in, I will try to AF and the camera will simply do nothing except maybe blink the numbers in the viewfinder. If I switch to manual, then I can focus fine and actuate the shutter. If I zoom out, the AF then begins to work fine. This is all in "Auto" mode.

Any ideas as to what might be going on?

04-15-2021, 11:37 AM   #2
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Do you think this might be related to the previous problem?

Post-Repair AF Weirdness in K-1 - PentaxForums.com


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04-15-2021, 12:12 PM   #3
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Are you focusing using the viewfinder (phase focusing) or Liveview (contrast focus)? If your lens doesn't have a suitable lowest f-stop, the latter may not have enough light to get a good focus, hence when you zoom out, the f-stop decreases slightly which might be the reason it can then focus. Try a lens with a bit more light gathering power (lower maximum f-stop) and see if it improves focusing performance. You didn't mention the f-stop rating of your lens and if it's the f2.8 Tamron, this probably doesn't apply)

I know my zoom which is an f3.8-f5.6 lens, won't work well at all with my K-1 in Liveview mode in dim conditions. As in your case, if it has outdoor light, no problems exist. Using the viewfinder AF, it works in even dim conditions pretty well. If I put an f2.8 lens on the K-1, it works well in most any light and with either phase focus or the Liveview mode.

Just a possibility - it could still be an issue related to the repair (maybe something occluding the AF sensor or an electronic issue).

Last edited by Bob 256; 04-15-2021 at 12:21 PM.
04-15-2021, 01:05 PM   #4
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Does it happen with any other lens?

04-16-2021, 05:01 AM - 1 Like   #5
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QuoteOriginally posted by stevebrot Quote
Do you think this might be related to the previous problem?

Post-Repair AF Weirdness in K-1 - PentaxForums.com


Steve
Steve,

That's what I'm trying to figure out. I'm trying to determine if I'm the crazy one here, and just being over sensitive.

---------- Post added 04-16-21 at 05:06 AM ----------

QuoteOriginally posted by Bob 256 Quote
Are you focusing using the viewfinder (phase focusing) or Liveview (contrast focus)? If your lens doesn't have a suitable lowest f-stop, the latter may not have enough light to get a good focus, hence when you zoom out, the f-stop decreases slightly which might be the reason it can then focus. Try a lens with a bit more light gathering power (lower maximum f-stop) and see if it improves focusing performance. You didn't mention the f-stop rating of your lens and if it's the f2.8 Tamron, this probably doesn't apply)

I know my zoom which is an f3.8-f5.6 lens, won't work well at all with my K-1 in Liveview mode in dim conditions. As in your case, if it has outdoor light, no problems exist. Using the viewfinder AF, it works in even dim conditions pretty well. If I put an f2.8 lens on the K-1, it works well in most any light and with either phase focus or the Liveview mode.

Just a possibility - it could still be an issue related to the repair (maybe something occluding the AF sensor or an electronic issue).
Bob,

Thank you!

I am using the f/2.8 Tamron lens.

I was focusing TTV.

I should say that, even in outdoor light, if the lens is out of focus enough, it won't activate well, and I have to manually bring it closer.

---------- Post added 04-16-21 at 05:10 AM ----------

QuoteOriginally posted by UncleVanya Quote
Does it happen with any other lens?
UncleVanya,

It was happening badly enough with the Pentax-D FA 28-105 which I acquired in the last couple months that I thought it was the lens and sent it back for warranty repair recently.


I also have an old Promaster 70-300 lens which I got from an auction, which won't move with the AF on the K-1.

I just received a battery for a couple old bodies with AF and I'm going to try to see if they will focus the 70-200 and the 70-300, as well as a couple older AF Pentax lenses, and see what happens in like-condition comparisons.
04-16-2021, 07:17 AM   #6
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It does sound like a focus motor issue at this point. On the 70-200, can you take it off the camera and focus it manually while watching the focus screw? Does the mechanism turn freely? A focus motor should be able to turn the focus screw if it's not binding and since you're seeing this with more than one lens, it could be something that happened with the motor or electronics that's affecting the camera's ability to focus. If it were I, I would try one more lens (perhaps you can borrow one or go to a camera store and ask to use a demo) and if has the same issue, back to Precision with the K-1.
04-16-2021, 07:46 AM   #7
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QuoteOriginally posted by Bob 256 Quote
It does sound like a focus motor issue at this point. On the 70-200, can you take it off the camera and focus it manually while watching the focus screw? Does the mechanism turn freely? A focus motor should be able to turn the focus screw if it's not binding and since you're seeing this with more than one lens, it could be something that happened with the motor or electronics that's affecting the camera's ability to focus. If it were I, I would try one more lens (perhaps you can borrow one or go to a camera store and ask to use a demo) and if has the same issue, back to Precision with the K-1.
Bob,

I will check it out. I know that, on the old 70-300, I tested the manual focus and can see the mechanism turning freely. I have 3 - 5 older Pentax lenses I can use.

I'm also planning to video the issues, so maybe that will help convince Precision there is something up. I'm somewhat irritated that this would be a third send to Precision. They didn't charge me the second time, so that's good. However, being without my only dSLR body is bothersome, especially during spring when it's so beautiful and flowering here.
04-16-2021, 11:13 AM   #8
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QuoteOriginally posted by jawats Quote
Bob,

I will check it out. I know that, on the old 70-300, I tested the manual focus and can see the mechanism turning freely. I have 3 - 5 older Pentax lenses I can use.

I'm also planning to video the issues, so maybe that will help convince Precision there is something up. I'm somewhat irritated that this would be a third send to Precision. They didn't charge me the second time, so that's good. However, being without my only dSLR body is bothersome, especially during spring when it's so beautiful and flowering here.

Fully understandable. Usually, a service center should fully check out features before returning a repair, but nowadays it seems everyone likes to take shortcuts that can lead to customer unhappiness and yet another return. Hope you get the issue quickly resolved this time (and again no charge).


Last edited by Bob 256; 04-16-2021 at 11:19 AM.
04-16-2021, 06:34 PM   #9
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QuoteOriginally posted by jawats Quote

I also have an old Promaster 70-300 lens which I got from an auction, which won't move with the AF on the K-1.

I just received a battery for a couple old bodies with AF and I'm going to try to see if they will focus the 70-200 and the 70-300, as well as a couple older AF Pentax lenses, and see what happens in like-condition comparisons.
That sounds like an excellent plan to figure more out about this issue.
04-18-2021, 10:42 PM   #10
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I'm wondering if taking it off Auto might help. Maybe try in AV mode where you have control over the aperture. Maybe testing at various apertures will yield different results?
04-19-2021, 07:45 AM   #11
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QuoteOriginally posted by UncleVanya Quote
That sounds like an excellent plan to figure more out about this issue.
So, I tried the 70-300 on the old SF body I have, and while noisy, it focused every time. After I put it on the K-1, it was fine at first, then suddenly stopped focusing (seemingly when I got into lower light).

It seems to be an issue with low-light. I've noticed that, when I had my SMC-A 50 1.7 on the K-1 yesterday, it was fine with giving me "in focus" beeps outdoors, and worked quite well. In indoor light - not dim, just indoor lighting, even at 1.7, it never gave me the "in focus beeps."

---------- Post added 04-19-21 at 07:46 AM ----------

QuoteOriginally posted by peggers Quote
I'm wondering if taking it off Auto might help. Maybe try in AV mode where you have control over the aperture. Maybe testing at various apertures will yield different results?
I put it in full manual and / or opened the aperture physically to the widest. It seems like I'm narrowing it down to issues in lower-light (not "dark" - just indoor) that produce focus issues.
04-19-2021, 09:19 PM   #12
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QuoteOriginally posted by jawats Quote
So, I tried the 70-300 on the old SF body I have, and while noisy, it focused every time. After I put it on the K-1, it was fine at first, then suddenly stopped focusing (seemingly when I got into lower light).

It seems to be an issue with low-light. I've noticed that, when I had my SMC-A 50 1.7 on the K-1 yesterday, it was fine with giving me "in focus" beeps outdoors, and worked quite well. In indoor light - not dim, just indoor lighting, even at 1.7, it never gave me the "in focus beeps."

---------- Post added 04-19-21 at 07:46 AM ----------



I put it in full manual and / or opened the aperture physically to the widest. It seems like I'm narrowing it down to issues in lower-light (not "dark" - just indoor) that produce focus issues.
Something like that happens with SDM lenses but the problem follows the lens not the camera body. Low light IS harder to focus in - so problems are expected to be worse in low light but I wouldn't ever expect the old SF body to focus better than the K-1 in low light.

I'm stumped.
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