Can someone check the accuracy/difference of all AF points in AF-S Select

**StigVidar** · 06-25-2022, 01:04 PM - **1 Like**

Originally posted by UncleVanya

Did the 11-18 work will with previous bodies for you on off axis focus points?

I checked my K-3 and it has the same problem with outer af points as my K-3 III. I am also mostly using the center points so no big deal for me. It seems to me that this issue is only with wide angle lenses.

**BigMackCam** · 06-25-2022, 01:14 PM

Originally posted by StigVidar

I checked my K-3 and it has the same problem with outer af points as my K-3 III. I am also mostly using the center points so no big deal for me. It seems to me that this issue is only with wide angle lenses.

Just a thought...

I recently noticed that I was getting inaccurate focus with my DA20-40 when using outer AF points, despite the focus being accurate with the centre AF point (I most-often use centre AF and re-compose, hence why I hadn't noticed this before). I re-performed AF fine tuning, but did so using the left-most AF point. When I'd finished, both centre and off-centre AF points provided good results. It has actually made a BIG difference to my use of the lens. I wonder if the same would work with the 11-18 and 16-50 lenses on the K-3 and K-3III? Might be worth trying...

Settesz · 06-25-2022, 02:54 PM

Originally posted by BigMackCam

Just a thought...

I recently noticed that I was getting inaccurate focus with my DA20-40 when using outer AF points, despite the focus being accurate with the centre AF point (I most-often use centre AF and re-compose, hence why I hadn't noticed this before). I re-performed AF fine tuning, but did so using the left-most AF point. When I'd finished, both centre and off-centre AF points provided good results. It has actually made a BIG difference to my use of the lens. I wonder if the same would work with the 11-18 and 16-50 lenses on the K-3 and K-3III? Might be worth trying...

I've done the same with my K3iii and 16-50 PLM but it turned out that setting correction for outer points messed with the central ones.
None of my other lenses exhibited this behavior.
Since it happens with other camera models it makes me wonder if it's a lens problem after all.

**BigMackCam** · 06-25-2022, 02:59 PM

Originally posted by Settesz

I've done the same with my K3iii and 16-50 PLM but it turned out that setting correction for outer points messed with the central ones.
None of my other lenses exhibited this behavior.
Since it happens with other camera models it makes me wonder if it's a lens problem after all.

Gotcha. Well, worth a try

Does the K-3III focus correctly with central and outer AF points and other lenses? Sorry, I'm sure this must have been discussed earlier or before, but I can't recall...

Settesz · 06-25-2022, 09:24 PM

Originally posted by BigMackCam

Gotcha. Well, worth a try

Does the K-3III focus correctly with central and outer AF points and other lenses? Sorry, I'm sure this must have been discussed earlier or before, but I can't recall...

In my case 16-50 PLM focused correctly with 3 central f2.8 points, other needed -7 correction but as central points were good with 0 correction it messed them up.
Other lenses work fine with all af points, 16-50 SDM among them so I dont think it's about bright and wide lens.

**StigVidar** · 06-26-2022, 01:35 AM

Marianne Oelund at the dpreview forum (Nikon section) has written a lot about how af works. Interesting, but quite technical.

https://photonstophotos.net/MarianneOelund/AutoFocus_System_Design/AutoFocus_System_Design.htm

Quote:

As the projected image in this example is only around 4mm wide, we see that the image shift is even less than 1mm - not much for a 105mm lens changing from infinity to 1m focus. One can imagine how small the shifts are for f/5.6 AF sensors when wide-angle lenses are used.

ShawnH · 07-07-2022, 12:03 AM

You could have lens elements that are misaligned and project a skew plane of focus. I have observed the same issues with K70 & KS2. You can split the difference in adjustment between the center point and side points if the difference is consistent. Also I have noticed (not 100% sure) that FS & FA setting produce different adjustment values using the Dot-tune method. Note: A curved plane of focus inherent in the lens design may cause this issue.

Last edited by ShawnH; 07-07-2022 at 12:09 AM.

**StigVidar** · 07-07-2022, 01:31 AM - **1 Like**

Originally posted by ShawnH

FS & FA setting

What is the FS & FA setting?

ShawnH · 07-07-2022, 07:57 AM

Sorry late night typing. AFA & AFS.

---------- Post added 07-07-22 at 08:47 AM ----------

Sorry late night typing. AFA & AFS

licht96 · 07-07-2022, 10:43 AM

Still night? ;-)

What is AFA and AFS?

Do you mean AF S and AF C?

**UncleVanya** · 07-07-2022, 12:17 PM

Originally posted by licht96

Still night? ;-)

What is AFA and AFS?

Do you mean AF S and AF C?

AFA is auto mode - the camera decides if continuous or single focus is needed.

**Larrymc** · 07-07-2022, 02:15 PM

Originally posted by UncleVanya

AFA is auto mode - the camera decides if continuous or single focus is needed.

AF.A is a K-3 Mk I feature and possibly the Mk II, the Mk III doesn't have an AF.A feature that is listed in the manual. I've never used nor seen it used on the Mk I.

Euan · 10-25-2022, 01:27 PM - **1 Like**

I don't suppose there's been any change with respect to this issue with the new firmware that just came out? Has anybody been able to test it?

Levus · 10-26-2022, 12:10 AM

I had a topic before on the name K3 III AF Adjustment anomalies and i think that the cause of all of this are the different AF Adjustment calibration needed for the outer AF Points and additionally the different calibration needed for the different zoom ranges of the zoom lenses.

So at the end i decided to give up calibrating for the center point. Yes i do the AF calibration for the center point but after that i take quite a few shots with different focus points and in different focus modes and take the one AF Adjustment setting which seems to be the best all rounder.
For example my 16-50 is sharpest on the long end with AF Adjustment value +5, but using overally in all range and especially with the AF auto area mode, it's giving the most satisfactory result with AF Adjustment +4 for most of the pictures.

To be honest with the old K3 i was never using the AF auto area modes while with the K3 III i tend to use it mostly. So calibrating only for the center point is quite useless. Maybe if Pentax could implement AF Adjustment for several AF points individually then we would have a perfect calibration.

And to be honest again, it's only pixel peeping as the machine is taking exceptionally good pictures and the focus is generally fast, good and accurate. Only if some are doing AF Adjustment then it's easy to fall in the trap of pixel peeping.

sebberry · 10-26-2022, 08:39 AM

These are the issues that have me so on-the-fence about new lens purchases. If a zoom lens needs different AF adjustments at different focal lengths, and if the AF adjustments aren't consistent across the frame, how is anyone supposed to get a sharp photo?

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06-25-2022, 01:04 PM - 1 Like	#136
StigVidar Site Supporter Join Date: Nov 2006 Location: Norway Photos: Gallery \| Albums Posts: 705	Originally posted by UncleVanya Did the 11-18 work will with previous bodies for you on off axis focus points? I checked my K-3 and it has the same problem with outer af points as my K-3 III. I am also mostly using the center points so no big deal for me. It seems to me that this issue is only with wide angle lenses.

06-25-2022, 01:14 PM	#137
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,670	Originally posted by StigVidar I checked my K-3 and it has the same problem with outer af points as my K-3 III. I am also mostly using the center points so no big deal for me. It seems to me that this issue is only with wide angle lenses. Just a thought... I recently noticed that I was getting inaccurate focus with my DA20-40 when using outer AF points, despite the focus being accurate with the centre AF point (I most-often use centre AF and re-compose, hence why I hadn't noticed this before). I re-performed AF fine tuning, but did so using the left-most AF point. When I'd finished, both centre and off-centre AF points provided good results. It has actually made a BIG difference to my use of the lens. I wonder if the same would work with the 11-18 and 16-50 lenses on the K-3 and K-3III? Might be worth trying...

06-25-2022, 02:54 PM	#138
Settesz Forum Member Join Date: Apr 2021 Posts: 65	Originally posted by BigMackCam Just a thought... I recently noticed that I was getting inaccurate focus with my DA20-40 when using outer AF points, despite the focus being accurate with the centre AF point (I most-often use centre AF and re-compose, hence why I hadn't noticed this before). I re-performed AF fine tuning, but did so using the left-most AF point. When I'd finished, both centre and off-centre AF points provided good results. It has actually made a BIG difference to my use of the lens. I wonder if the same would work with the 11-18 and 16-50 lenses on the K-3 and K-3III? Might be worth trying... I've done the same with my K3iii and 16-50 PLM but it turned out that setting correction for outer points messed with the central ones. None of my other lenses exhibited this behavior. Since it happens with other camera models it makes me wonder if it's a lens problem after all.

06-25-2022, 02:59 PM	#139
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,670	Originally posted by Settesz I've done the same with my K3iii and 16-50 PLM but it turned out that setting correction for outer points messed with the central ones. None of my other lenses exhibited this behavior. Since it happens with other camera models it makes me wonder if it's a lens problem after all. Gotcha. Well, worth a try Does the K-3III focus correctly with central and outer AF points and other lenses? Sorry, I'm sure this must have been discussed earlier or before, but I can't recall...

06-25-2022, 09:24 PM	#140
Settesz Forum Member Join Date: Apr 2021 Posts: 65	Originally posted by BigMackCam Gotcha. Well, worth a try Does the K-3III focus correctly with central and outer AF points and other lenses? Sorry, I'm sure this must have been discussed earlier or before, but I can't recall... In my case 16-50 PLM focused correctly with 3 central f2.8 points, other needed -7 correction but as central points were good with 0 correction it messed them up. Other lenses work fine with all af points, 16-50 SDM among them so I dont think it's about bright and wide lens.

06-26-2022, 01:35 AM	#141
StigVidar Site Supporter Join Date: Nov 2006 Location: Norway Photos: Gallery \| Albums Posts: 705	Marianne Oelund at the dpreview forum (Nikon section) has written a lot about how af works. Interesting, but quite technical. https://photonstophotos.net/MarianneOelund/AutoFocus_System_Design/AutoFocus_System_Design.htm Quote: As the projected image in this example is only around 4mm wide, we see that the image shift is even less than 1mm - not much for a 105mm lens changing from infinity to 1m focus. One can imagine how small the shifts are for f/5.6 AF sensors when wide-angle lenses are used.

07-07-2022, 12:03 AM	#142
ShawnH Forum Member Join Date: May 2017 Posts: 65	You could have lens elements that are misaligned and project a skew plane of focus. I have observed the same issues with K70 & KS2. You can split the difference in adjustment between the center point and side points if the difference is consistent. Also I have noticed (not 100% sure) that FS & FA setting produce different adjustment values using the Dot-tune method. Note: A curved plane of focus inherent in the lens design may cause this issue. Last edited by ShawnH; 07-07-2022 at 12:09 AM.

07-07-2022, 01:31 AM - 1 Like	#143
StigVidar Site Supporter Join Date: Nov 2006 Location: Norway Photos: Gallery \| Albums Posts: 705	Originally posted by ShawnH FS & FA setting What is the FS & FA setting?

07-07-2022, 07:57 AM	#144
ShawnH Forum Member Join Date: May 2017 Posts: 65	Sorry late night typing. AFA & AFS. ---------- Post added 07-07-22 at 08:47 AM ---------- Sorry late night typing. AFA & AFS

07-07-2022, 10:43 AM	#145
licht96 Forum Member Join Date: Jan 2021 Location: Braunschweig Posts: 92 Original Poster	Still night? ;-) What is AFA and AFS? Do you mean AF S and AF C?

07-07-2022, 12:17 PM	#146
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,401	Originally posted by licht96 Still night? ;-) What is AFA and AFS? Do you mean AF S and AF C? AFA is auto mode - the camera decides if continuous or single focus is needed.

07-07-2022, 02:15 PM	#147
Larrymc Site Supporter Join Date: Jun 2014 Location: Mississippi, USA Posts: 5,251	Originally posted by UncleVanya AFA is auto mode - the camera decides if continuous or single focus is needed. AF.A is a K-3 Mk I feature and possibly the Mk II, the Mk III doesn't have an AF.A feature that is listed in the manual. I've never used nor seen it used on the Mk I.

10-25-2022, 01:27 PM - 1 Like	#148
Euan New Member Join Date: Apr 2009 Posts: 18	I don't suppose there's been any change with respect to this issue with the new firmware that just came out? Has anybody been able to test it?

10-26-2022, 12:10 AM	#149
Levus Junior Member Join Date: Apr 2020 Location: Hungary Posts: 31	I had a topic before on the name K3 III AF Adjustment anomalies and i think that the cause of all of this are the different AF Adjustment calibration needed for the outer AF Points and additionally the different calibration needed for the different zoom ranges of the zoom lenses. So at the end i decided to give up calibrating for the center point. Yes i do the AF calibration for the center point but after that i take quite a few shots with different focus points and in different focus modes and take the one AF Adjustment setting which seems to be the best all rounder. For example my 16-50 is sharpest on the long end with AF Adjustment value +5, but using overally in all range and especially with the AF auto area mode, it's giving the most satisfactory result with AF Adjustment +4 for most of the pictures. To be honest with the old K3 i was never using the AF auto area modes while with the K3 III i tend to use it mostly. So calibrating only for the center point is quite useless. Maybe if Pentax could implement AF Adjustment for several AF points individually then we would have a perfect calibration. And to be honest again, it's only pixel peeping as the machine is taking exceptionally good pictures and the focus is generally fast, good and accurate. Only if some are doing AF Adjustment then it's easy to fall in the trap of pixel peeping.

10-26-2022, 08:39 AM	#150
sebberry Pentaxian Join Date: Jan 2009 Location: Frozen white North Photos: Albums Posts: 1,135	These are the issues that have me so on-the-fence about new lens purchases. If a zoom lens needs different AF adjustments at different focal lengths, and if the AF adjustments aren't consistent across the frame, how is anyone supposed to get a sharp photo?