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05-20-2021, 08:13 AM   #1
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KP focus problems

On my KP none of my lenses focus "right" without adjustment, and *all* of my zooms FF at the long end and BF at the short end. Even my DA 20-40 Ltd. bought new from B&H.

My K-3 seems to have the same problem.

My old battered and tattered K-5 that once fell 7 feet onto solid concrete? No issues at all. I never even realized there was a fine tuning adjustment with that camera... because I never needed it.

Are my KP and K-3 both off by sheer luck? I ask because I know they've been tweaking AF algorithms via firmware a LOT in recent years. I know that all the AF advantage of the K-3 II over the K-3 (the II was said to be slightly better upon release) came to the K-3 via a firmware update. I'm worried that this algorithm-tweaking may have messed stuff up, since the K-3 and KP have been updated several times, but the K-5 hasn't had a firmware update in quite a long time now.

So I just want to make sure before I send the KP off to Precision for warranty service on the phase detect system. (They seem to charge a minimum of $344 for out-of-warranty service, so sending the K-3 in is a no-go, I can just get another one for $350-400 all day long.)

Edit:// I should note that I'm not just going by the image. The lenses are physically focusing to a different point in the distance scale when on the K-5 relative to the other two.


Last edited by Volvo244T; 05-20-2021 at 09:32 AM.
05-20-2021, 08:27 AM   #2
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The higher the resolution, the more you can notice slight focus errors, blur from camera shake, etc. In addition, for zooms you have to strike a balance that works well enough, but yes it's possible to have both bf and ff. That can happen at different focusing distances too.. How much is it back focusing or front focusing, do you notice it in normal use or when looking for it to test? I did a lot of careful af fine tuning when I had my k3ii. Then the camera firmware was reset from service (unrelated issue), then forgot to fine tune and realized a few months later that I wasn't missing anything. Haven't done it since, never touched that menu on the k1ii
05-20-2021, 08:32 AM   #3
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If it was just a minor difference that would go away upon scaling down the image for normal viewing I wouldn't be the least bit worried but it's bad enough to be pretty obvious. That is to say, it's not slight, it's significant.
05-20-2021, 08:42 AM   #4
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QuoteOriginally posted by Volvo244T Quote
On my KP none of my lenses focus "right" without adjustment, and *all* of my zooms FF at the long end and BF at the short end. Even my DA 20-40 Ltd. bought new from B&H.

My K-3 seems to have the same problem.

My old battered and tattered K-5 that once fell 7 feet onto solid concrete? No issues at all. I never even realized there was a fine tuning adjustment with that camera... because I never needed it.

Are my KP and K-3 both off by sheer luck? I ask because I know they've been tweaking AF algorithms via firmware a LOT in recent years. I know that all the AF advantage of the K-3 II over the K-3 (the II was said to be slightly better upon release) came to the K-3 via a firmware update. I'm worried that this algorithm-tweaking may have messed stuff up, since the K-3 and KP have been updated several times, but the K-5 hasn't had a firmware update in quite a long time now.

So I just want to make sure before I send the KP off to Precision for warranty service on the phase detect system. (They seem to charge a minimum of $344 for out-of-warranty service, so sending the K-3 in is a no-go, I can just get another one for $350-400 all day long.)
Read ur entry - I just got my K 30 back from Precision - I guess do charge about that amount except for cleaning - my cleaning charge was under a hundred and that included shipping if that any help

05-20-2021, 08:59 AM   #5
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This is pretty normal for zooms. It seems like a property of the lens rather than the camera.

I had 60-250 that had substantial FF/BF issues at different ends of the zoom range.

I returned it and got another one some time afterwards. The new one was much better. This was on the same camera.

It would be nice if Pentax offered some kind of multi-point calibration throughout the zoom range rather than one calibration for the whole lens.
05-20-2021, 09:19 AM   #6
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As noted above, with higher resolution come the price of knowing flaws in technique or gear. In the case of front or back focus with PDAF (viewfinder) autofocus, the fault is usually with the lens. If won't hurt to send the KP in for service and they might be able to do an adjustment that will help, if that you want to go that route.


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05-20-2021, 09:29 AM   #7
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I should note that I'm not just going by the image. The lenses are physically focusing to a different point in the distance scale when on the K-5 relative to the other two.

05-20-2021, 09:59 AM   #8
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QuoteOriginally posted by Volvo244T Quote
I should note that I'm not just going by the image. The lenses are physically focusing to a different point in the distance scale when on the K-5 relative to the other two.
That would make sense.


Steve
05-20-2021, 10:12 AM   #9
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QuoteOriginally posted by Volvo244T Quote
On my KP none of my lenses focus "right" without adjustment, and *all* of my zooms FF at the long end and BF at the short end. Even my DA 20-40 Ltd. bought new from B&H.

My K-3 seems to have the same problem.

My old battered and tattered K-5 that once fell 7 feet onto solid concrete? No issues at all. I never even realized there was a fine tuning adjustment with that camera... because I never needed it.

Are my KP and K-3 both off by sheer luck? I ask because I know they've been tweaking AF algorithms via firmware a LOT in recent years. I know that all the AF advantage of the K-3 II over the K-3 (the II was said to be slightly better upon release) came to the K-3 via a firmware update. I'm worried that this algorithm-tweaking may have messed stuff up, since the K-3 and KP have been updated several times, but the K-5 hasn't had a firmware update in quite a long time now.

So I just want to make sure before I send the KP off to Precision for warranty service on the phase detect system. (They seem to charge a minimum of $344 for out-of-warranty service, so sending the K-3 in is a no-go, I can just get another one for $350-400 all day long.)
Neither my DA 55-300mm PLM nor my DA 20-40mm Ltd shows any problem with focusing.
I do tend to use the 20-40mm at apertures {such as f/5.6} that might hide some problems, but I generally tend to use the 55-300mm close to the largest {size of opening} aperture available.

added: Last December, one of our cats jumped onto my lap, and the KP fell several feet to a carpeted floor - suddenly it could not focus at all.
After several hours of pondering my options, I did a 'cold reboot' by removing the battery for a few minutes - and then it worked fine again.

Last edited by reh321; 05-20-2021 at 10:18 AM.
05-20-2021, 01:40 PM   #10
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Do these lenses focus correctly in Live-view on the K-3 and KP?
05-20-2021, 01:48 PM   #11
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Hadn't tested with LV, but just tested one, dead on every time.
05-20-2021, 03:06 PM   #12
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I have had a KP for nearly three years and the focus has always been good. I bought a second one early this year and it had a focus problem, so far off that I could not even adjust the lenses. I sent that back to Adorama and they sent a new one that was perfect. I'm sure the one went back to Precision, was fixed and on to Ricoh's website to sell as refurbished. Yours is obviously not right and if it is under warranty send it in right away. Now if the caliber of my skills were up to the caliber of the tools...
05-20-2021, 08:44 PM   #13
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QuoteOriginally posted by Volvo244T Quote
On my KP none of my lenses focus "right" without adjustment
As long as everything works within -10 to +10, that's fine, it's what the adjustment process is for, Cullen. Nobody's measurements of their own systems have any relevance to you

It's when they're outside that range that something's wrong that you as the end user can't do anything about.
05-21-2021, 06:51 AM   #14
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QuoteOriginally posted by clackers Quote
As long as everything works within -10 to +10, that's fine, it's what the adjustment process is for, Cullen. Nobody's measurements of their own systems have any relevance to you

It's when they're outside that range that something's wrong that you as the end user can't do anything about.
Surely one shouldn’t expect every zoom to front focus on the long end and back focus on the short end? There’s no way to fix that with a static focus adjustment.
05-21-2021, 08:16 AM   #15
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QuoteOriginally posted by UncleVanya Quote
Surely one shouldn’t expect every zoom to front focus on the long end and back focus on the short end? There’s no way to fix that with a static focus adjustment.
C'est la vie...


Steve

(...has found that people often what they want to find when doing AF fine adjust...mine need little adjustment...)
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