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12-07-2017, 08:42 PM   #1
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K3-II focus issues

I'm not sure how or when this issue popped up, but my Pentax K3-II can't focus correctly anymore. I tried on both my lenses and encountered the same issue:
DA* 16-50mm
DA* 50-135mm

Following advice elsewhere on Pentax Forums I adjusted the AF fine adjustment to +10, which almost has it right, however I've noticed that when shooting at f2.8 the picture seems hazy, especially towards the edges of the image. Even at f22 the image isn't completely clear. Here are a couple of sample shots:

DA* 16-50mm
f2.8 ISO100 - AF point at white dot with +10 AF fine adjustment
https://i.imgur.com/FFpvjsv.jpg

DA* 50-135mm
f2.8 ISO100
https://i.imgur.com/L130nNb.jpg

DA* 50-135mm
f22 ISO100
https://i.imgur.com/1rkD5oJ.jpg

Is this something I can fix myself or a service centre job?

12-07-2017, 09:34 PM   #2
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Hello enricoman,
You might have some dust or similar on the phase detect sensor.
You could try mirror-up cleaning with a rocket blower (Giotto or similar) whilst holding the camera mount facing down.
If there is any foreign matter there it will affect the focussing.
Let's know how you get on.

Cheers,
Terry
12-07-2017, 11:00 PM   #3
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To eliminate the sensor as the source of the problem, are you able to get acceptably sharp photos in live view and with manual focus?

Adam
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12-08-2017, 01:32 AM   #4
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Hello Enricoman,
I had thee same probleem wit My K3 ii and soms limieten lenses. After clearing thee contact of thee lenses and thee camera wit 90% alcohol thee probleem has disappeared and thee focussen is correct. Just try It.

12-08-2017, 01:52 AM   #5
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Have you tried different apertures? You appear to be using the extremes of the lenses- I would suggest you try f8-f11. If they're hazy then you have a problem.
12-08-2017, 07:05 AM   #6
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Others have suggested good ideas, but let me ask this. Do you have any other autofocus lenses? Are any of the other lenses able to focus correctly? When you use the lenses with problems do they hunt focus and eventually give up without achieving it? Or do they chirp and lock in immediately but inaccurately?
12-08-2017, 09:37 AM   #7
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Nascent SDM failure?
12-08-2017, 12:59 PM   #8
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I think it should be pointed out that the subjects of the example images #2 and #3 are flat art and not actual 3-D objects. I believe the same is true of #1, based on the rendering of the white circle. I also noted that the white circle in the first example has only limited detail for the camera to focus on.

Adam is correct in suggesting that the lenses be tested in live view to rule out issues on the sensor side of things (e.g. botched wet cleaning) and/or poorly-performed PDAF fine adjustment.


Steve

12-10-2017, 06:59 PM   #9
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Hey, thanks for the detailed replies everyone and sorry for the late follow-up. I'm running through the suggestions now beginning with cleaning the contacts on the camera & lenses with isopropyl alcohol. I'll report back in with results.
01-20-2018, 04:43 PM   #10
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Hello,

I join on this, because I too have AF issues, two different problems actually ..

It is on a used K3 that I just bought.

First, I have trouble finding the af focus point, whatever the lens.
Settings : AF.S, spot or SEL1 (dot). It's not FF or BF because I know my lenses.
I think instead of a AF Phase detect sensor problem ; I do not see anything on the second mirror?
It's not catastrophic, but the point of focus is never accurate. It's not the sensor, it's perfect in liveview.
What do you think?

Then there is the problem of the memory of af with the shutter button half-pressed or the button af to a lesser extent: when I focus on a subject and I want to change the frame while holding the shutter button, when I push hard, it sneaks the focus partially again, and I can see for a moment the red dot in the viewfinder. Seldom, I can even ear the 'bip'..
A bit like he would do in AF.C ..

Could both problems be linked? Not sure..

If you need more info, ask! Thank you for your opinions!
Sorry for my bad English..

Thanks!
01-20-2018, 07:35 PM   #11
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What do you mean by the "second mirror"?

My feel is that you bought a bad camera; return it if it was not as advertised.

The buttons make intermittent contact and hence it sometimes refocuses; this can probably be solved with contact cleaner although I have no idea how to do it on a WR camera body (you might have to strip it).

PS
I do not have a K3/II (nor K3).
01-21-2018, 06:41 AM   #12
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Thanks for your reply!

By the "second mirror", I mean the one at the bottom of the inner space of the K3, used by the AF sensor to focus..

Indeed, if someone had an idea on how to put contact cleaner "inside" the shutter button, "from outside"...?
I bought it from the web, and it could be difficult to send it back...unfortunatly.

Is there anything else I could try?
Thanks!
01-21-2018, 09:32 AM   #13
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Front and back focus have to do with the COMBINATION of lens and body. If your lenses work on another body in pdaf, and on the current body in CDAF, then I'd suspect front or back focusing. The high resolution of the 24mp sensor makes mount distances critical
01-21-2018, 02:29 PM   #14
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I'm not really sure about FF and BF, but on a tripod, the focus point is often not accurate, sometimes before, sometimes behind what's in focus.

But the biggest issue is the AF memory when shutter button is half-pressed : in 50 % of the time, when I hold the half-pressed shutter button, and I then change the frame, the K3 re-focuses !
A shutter button (contact ?) issue ? Any other idea ?

Thanks a lot !
01-21-2018, 03:47 PM   #15
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QuoteOriginally posted by néonaloj Quote
I'm not really sure about FF and BF, but on a tripod, the focus point is often not accurate, sometimes before, sometimes behind what's in focus.

But the biggest issue is the AF memory when shutter button is half-pressed : in 50 % of the time, when I hold the half-pressed shutter button, and I then change the frame, the K3 re-focuses !
A shutter button (contact ?) issue ? Any other idea ?

Thanks a lot !
1 I, too, am a newbie and trying to learn

2 I am also easily confused

3 are you just depressing the shutter half way to gain focus

4 if you should consider using the back button focus method

https://www.pentaxforums.com/forums/172-pentax-k-3/347010-back-button-focus-3.html#post4013107

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