K-3 AF Testing

audiobomber · 11-14-2013, 11:20 AM

I believe there is a standard calibration that Pentax aspires to with all bodies. Cameras coming off the line are sometimes a bit off this standard. The same applies to lenses. There is a standard, but some deviation in individual units.

AF Adjust is a handy feature, but not a full solution for me because I had one body with calibration, one without. My solution was to make sure each camera and lens met the Pentax calibration standard with no deviation. The K20D was good from the start, matching most of my lenses with no AF Adjust needed. The first time I sent a lens in, the FA 35mm, I asked them to check calibration on the K20D and lens.

I used the global adjust firmware to calibrate the K-x myself. The K-5 I bought had a different problem. The calibration was right on in daylight, but the AF module was defective, it varied to a ridiculous amount in yellow light. Others with this problem were reporting no relief when they sent the body to Pentax, so I sent mine back for a refund.

When I get a new lens, I test it with this chart. http://www.dphotojournal.com/focus-test-chart.pdf. If it shows front or rear focus, I send it to Pentax with a body and instructions not to change calibration on the camera. The only cost is that I lose the use of the lens for a few weeks and I have to pay for shipping one way. The benefit is that I have about 14 AF lenses and no need for AF Adjust.

Some lens experiences:

- The FA 35mm I paid to have calibrated (just over $100)
- The DA 15mm I received was off (+5). I sent it back, requesting a new copy. The replacement was accurate.
- DA*300mm, same situation as the 15mm. In addition, I didn't trust the SDM on that one. A couple of times it didn't focus at all, so I requested a new lens. The replacement was good
- With the 18-135mm, my copy was off (+10 on the K20D), but clearly a good copy when adjusted. I sent that one to Pentax Canada, with instructions to repair, not replace.
- My D FA 100mm needs focus adjustment on my K20D. It didn't use to, so something has changed. I will only be using it with the K-3, so I will use AF Adjust and keep on eye on it. If calibration changes again, I'll send it back to Pentax with the K20D, at my cost.

PS All of my lenses are Pentax.

**unkipunki** · 11-14-2013, 11:43 AM

Originally posted by audiobomber

My solution was to make sure each camera and lens met the Pentax calibration standard with no deviation..... The benefit is that I have about 14 AF lenses and no need for AF Adjust.

Thanks for the feedback.

I see, they calibrate the lenses. I wish I had been less 'British' about some of my lenses when I initially got them, as +6 to +7 has been required in the past, but I just AFadjusted them. Now they would all be at some cost to get calibrated. I'm not at all sure if the Pentax Service Centres here would do this in even a vaguely affordable manner. I will look into it though.

I now also understand your statement of the "worst case scenario" being global AFadjust for a new body. That would be a good situation to be in, although it could be a while before any new body finds it's way near my pentax glass.

Poit · 11-14-2013, 12:58 PM

Originally posted by jatrax

The -1 results above are the adjustment I made, the lenses were actually front focusing.Conclusion:
I am delighted with the k-3's AF ability, I did make an adjustment to the two SDM lenses, but to be honest most people would not be bothered by the difference a -1 adjustment will make. All of the other lenses performed spot on with hardly any variability (except the DA 40mm) between tests. Conditions were of course controlled and only one type of lighting was tested. However, I think this shows the AF in the k-3 (at least my sample) is accurate, fast, and reliable.

Thank you very much for your efforts.

For someone who has never had the time or inclination to learn how to test and/or calibrate lenses, it's wonderful to have people here who can do it on my behalf, and assure me I won't have to worry about it

**jatrax** · 11-14-2013, 01:05 PM

Originally posted by Poit

For someone who has never had the time or inclination to learn how to test and/or calibrate lenses, it's wonderful to have people here who can do it on my behalf, and assure me I won't have to worry about it

You are most welcome!

I am still surprised at the results. My k-5 (with the same lenses) required some adjustment on almost all of them. For the k-3 to be just spot on is remarkable. I hope some others will test and report their findings as well. Maybe, I just got the k-3 that was hand tuned by the QC people

If they are all this way it really makes the AF fine tuning function redundant......

I want to do further testing on the 60-250 and on my Sigma 50-500 but setting up a test with more distance will have to wait for better weather. I also want to see what the k-3 does with the Pentax A 400mm f/5.6 as far as focus indication.

**unkipunki** · 11-14-2013, 01:54 PM

Originally posted by jatrax

If they are all this way it really makes the AF fine tuning function redundant.......

Another thanks for your efforts

However I can assure you they are not all that way

. I am hoping that FocusTune (FT) will come to grips with the K-3 jpegs at some point soon (or I learn how to edit the EXIF such that FT can use them). When I can I will test all my lenses and post to the forum. However I have used the LensAlign ruler for calibration by eye and many of my lenses are not correctly focusing at the default AF setting. My DA*300 looks to need +4, my DA 35mm macro +3, DA 15mm ltd -3, DA 70mm ltd +1, DA*16-50 +6.

The DA*60-250 seems to be needing -5 at the wide end and -2 and the long end, and the 18-55 WR +5 and +3 respectively. This is where the FocusTune analysis is especially useful as it will help me make the best overall setting for the zooms. Maybe sacrificing the sharpest but going for the best average, or choosing which end of the range to optimise along with the mid ranges.

The AFA values above are not definitive, just my best estimate at present. These values are broadly linear with those AFA values required on my K5iis so the K-3 doesn't seem to be putting a whole new slant on my lenses. Of course it may be that I have poorly calibrated lenses in the first place (except DA 70mm ltd), but that would be a bit unlucky.

Anyhow I will post the results from FT analysis IF and when I can run the K-3 jpegs through it. I'm sure there are other great methods out there, but I'm invested in (and trust) FocusTune.

devorama · 11-15-2013, 08:39 AM

Originally posted by devorama

I'm curious if the focus is still stop on in different light. The OP calibrated in daylight corrected fluorescent bulbs. I had AF fine adjusted my DA70 on my K-3 to about a +2 to correct for a slight back focus. I did this in tungsten light at close to minimum focusing distance. But later I took some photos in daylight at about 20 feet, and they pictures looks slightly front focused. I'm not sure if it's due to the different light, or the focus distance, or both. Anyone check focus accuracy with different light sources and/or different distances?

Okay, so upon further testing in tungsten light, I've found my DA70 needs about a +2 correction at close distance of about 5 feet and about a -2 correction at larger distances like 12 feet. I guess I can split the difference and set it to 0 correction. Or adjust on the fly based on distance... Hmm... Too bad we can't tweak the AF fine adjust for lens AND distance.

JinDesu · 11-15-2013, 08:45 AM

Originally posted by devorama

Okay, so upon further testing in tungsten light, I've found my DA70 needs about a +2 correction at close distance of about 5 feet and about a -2 correction at larger distances like 12 feet. I guess I can split the difference and set it to 0 correction. Or adjust on the fly based on distance... Hmm... Too bad we can't tweak the AF fine adjust for lens AND distance.

Hello, Sigma dock! If only every manufacturer was nice like Sigma.

devorama · 11-15-2013, 08:51 AM

Originally posted by JinDesu

Hello, Sigma dock! If only every manufacturer was nice like Sigma.

Except there is no Pentax version of the sigma dock! :-(

JinDesu · 11-15-2013, 08:52 AM

Originally posted by devorama

Except there is no Pentax version of the sigma dock! :-(

Well yes they can be nicer

bxf · 11-15-2013, 12:54 PM

Originally posted by devorama

Okay, so upon further testing in tungsten light, I've found my DA70 needs about a +2 correction at close distance of about 5 feet and about a -2 correction at larger distances like 12 feet. I guess I can split the difference and set it to 0 correction. Or adjust on the fly based on distance... Hmm... Too bad we can't tweak the AF fine adjust for lens AND distance.

You forgot to include different settings for the various focal lengths of a zoom. Wayyy too many permutations/combinations, though ideally, that's exactly what is required.

devorama · 11-15-2013, 02:48 PM

Originally posted by bxf

You forgot to include different settings for the various focal lengths of a zoom. Wayyy too many permutations/combinations, though ideally, that's exactly what is required.

It is possible though. The Olympus OM-D E-M1 has not only the focus adjustment per lens, but also individually for each of its 37 phase detect sensors. And for zoom lenses, you can calibrate it at the both ends of the zoom range. This is the kind of thing that should be absolutely possible with modern hardware. Wouldn't it be awesome if Pentax would allow such things in a firmware update? In my case, it's not even a matter of focal length, since it's a prime lens. I'd just like it to be adjustable for focus distance.

ALiEN|PoV · 03-19-2014, 06:12 AM

Originally posted by devorama

It is possible though. The Olympus OM-D E-M1 has not only the focus adjustment per lens, but also individually for each of its 37 phase detect sensors. And for zoom lenses, you can calibrate it at the both ends of the zoom range. This is the kind of thing that should be absolutely possible with modern hardware. Wouldn't it be awesome if Pentax would allow such things in a firmware update? In my case, it's not even a matter of focal length, since it's a prime lens. I'd just like it to be adjustable for focus distance.

Slightly old thread, but still relevant.

IF I recall correctly you can store 20? individual lens adjustments.
I guess space is the problem, as the adjustments are maintained even without
a battery connected.

However, with 2 SD cards and the the overall speed; I'd say you could store
adjustments on a SD card. This would allow for way more complex AF
adjustments, like focal + Aperture + Tungsten, or focal + Aperture + Daylight. (theoretically).
And so on etc.

I'd link it with global adjustments, so the lens connected would be controlled by this preset.
Obviously, the access speed of the SD might be a factor. Adjustment linked Aperture might induce
AF lag, but you could always have the option to unlink it.

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11-14-2013, 11:20 AM	#16
audiobomber Veteran Member Join Date: May 2008 Location: Sudbury, Ontario Photos: Albums Posts: 6,806	I believe there is a standard calibration that Pentax aspires to with all bodies. Cameras coming off the line are sometimes a bit off this standard. The same applies to lenses. There is a standard, but some deviation in individual units. AF Adjust is a handy feature, but not a full solution for me because I had one body with calibration, one without. My solution was to make sure each camera and lens met the Pentax calibration standard with no deviation. The K20D was good from the start, matching most of my lenses with no AF Adjust needed. The first time I sent a lens in, the FA 35mm, I asked them to check calibration on the K20D and lens. I used the global adjust firmware to calibrate the K-x myself. The K-5 I bought had a different problem. The calibration was right on in daylight, but the AF module was defective, it varied to a ridiculous amount in yellow light. Others with this problem were reporting no relief when they sent the body to Pentax, so I sent mine back for a refund. When I get a new lens, I test it with this chart. http://www.dphotojournal.com/focus-test-chart.pdf. If it shows front or rear focus, I send it to Pentax with a body and instructions not to change calibration on the camera. The only cost is that I lose the use of the lens for a few weeks and I have to pay for shipping one way. The benefit is that I have about 14 AF lenses and no need for AF Adjust. Some lens experiences: - The FA 35mm I paid to have calibrated (just over $100) - The DA 15mm I received was off (+5). I sent it back, requesting a new copy. The replacement was accurate. - DA*300mm, same situation as the 15mm. In addition, I didn't trust the SDM on that one. A couple of times it didn't focus at all, so I requested a new lens. The replacement was good - With the 18-135mm, my copy was off (+10 on the K20D), but clearly a good copy when adjusted. I sent that one to Pentax Canada, with instructions to repair, not replace. - My D FA 100mm needs focus adjustment on my K20D. It didn't use to, so something has changed. I will only be using it with the K-3, so I will use AF Adjust and keep on eye on it. If calibration changes again, I'll send it back to Pentax with the K20D, at my cost. PS All of my lenses are Pentax.

11-14-2013, 11:43 AM	#17
unkipunki Site Supporter Join Date: Dec 2012 Location: South Lochaweside, Argyll Photos: Gallery Posts: 615	Originally posted by audiobomber My solution was to make sure each camera and lens met the Pentax calibration standard with no deviation..... The benefit is that I have about 14 AF lenses and no need for AF Adjust. Thanks for the feedback. I see, they calibrate the lenses. I wish I had been less 'British' about some of my lenses when I initially got them, as +6 to +7 has been required in the past, but I just AFadjusted them. Now they would all be at some cost to get calibrated. I'm not at all sure if the Pentax Service Centres here would do this in even a vaguely affordable manner. I will look into it though. I now also understand your statement of the "worst case scenario" being global AFadjust for a new body. That would be a good situation to be in, although it could be a while before any new body finds it's way near my pentax glass.

11-14-2013, 12:58 PM	#18
Poit Banned Join Date: Feb 2013 Location: Canberra, Australia Posts: 423	Originally posted by jatrax The -1 results above are the adjustment I made, the lenses were actually front focusing.Conclusion: I am delighted with the k-3's AF ability, I did make an adjustment to the two SDM lenses, but to be honest most people would not be bothered by the difference a -1 adjustment will make. All of the other lenses performed spot on with hardly any variability (except the DA 40mm) between tests. Conditions were of course controlled and only one type of lighting was tested. However, I think this shows the AF in the k-3 (at least my sample) is accurate, fast, and reliable. Thank you very much for your efforts. For someone who has never had the time or inclination to learn how to test and/or calibrate lenses, it's wonderful to have people here who can do it on my behalf, and assure me I won't have to worry about it

11-14-2013, 01:05 PM	#19
jatrax Site Supporter Join Date: May 2010 Location: Washington Cascades Photos: Gallery \| Albums Posts: 12,991 Original Poster	Originally posted by Poit For someone who has never had the time or inclination to learn how to test and/or calibrate lenses, it's wonderful to have people here who can do it on my behalf, and assure me I won't have to worry about it You are most welcome! I am still surprised at the results. My k-5 (with the same lenses) required some adjustment on almost all of them. For the k-3 to be just spot on is remarkable. I hope some others will test and report their findings as well. Maybe, I just got the k-3 that was hand tuned by the QC people If they are all this way it really makes the AF fine tuning function redundant...... I want to do further testing on the 60-250 and on my Sigma 50-500 but setting up a test with more distance will have to wait for better weather. I also want to see what the k-3 does with the Pentax A 400mm f/5.6 as far as focus indication.

11-14-2013, 01:54 PM	#20
unkipunki Site Supporter Join Date: Dec 2012 Location: South Lochaweside, Argyll Photos: Gallery Posts: 615	Originally posted by jatrax If they are all this way it really makes the AF fine tuning function redundant....... Another thanks for your efforts However I can assure you they are not all that way . I am hoping that FocusTune (FT) will come to grips with the K-3 jpegs at some point soon (or I learn how to edit the EXIF such that FT can use them). When I can I will test all my lenses and post to the forum. However I have used the LensAlign ruler for calibration by eye and many of my lenses are not correctly focusing at the default AF setting. My DA300 looks to need +4, my DA 35mm macro +3, DA 15mm ltd -3, DA 70mm ltd +1, DA16-50 +6. The DA*60-250 seems to be needing -5 at the wide end and -2 and the long end, and the 18-55 WR +5 and +3 respectively. This is where the FocusTune analysis is especially useful as it will help me make the best overall setting for the zooms. Maybe sacrificing the sharpest but going for the best average, or choosing which end of the range to optimise along with the mid ranges. The AFA values above are not definitive, just my best estimate at present. These values are broadly linear with those AFA values required on my K5iis so the K-3 doesn't seem to be putting a whole new slant on my lenses. Of course it may be that I have poorly calibrated lenses in the first place (except DA 70mm ltd), but that would be a bit unlucky. Anyhow I will post the results from FT analysis IF and when I can run the K-3 jpegs through it. I'm sure there are other great methods out there, but I'm invested in (and trust) FocusTune.

11-15-2013, 08:39 AM	#21
devorama Veteran Member Join Date: Apr 2009 Location: Chicago, IL Photos: Gallery \| Albums Posts: 638	Originally posted by devorama I'm curious if the focus is still stop on in different light. The OP calibrated in daylight corrected fluorescent bulbs. I had AF fine adjusted my DA70 on my K-3 to about a +2 to correct for a slight back focus. I did this in tungsten light at close to minimum focusing distance. But later I took some photos in daylight at about 20 feet, and they pictures looks slightly front focused. I'm not sure if it's due to the different light, or the focus distance, or both. Anyone check focus accuracy with different light sources and/or different distances? Okay, so upon further testing in tungsten light, I've found my DA70 needs about a +2 correction at close distance of about 5 feet and about a -2 correction at larger distances like 12 feet. I guess I can split the difference and set it to 0 correction. Or adjust on the fly based on distance... Hmm... Too bad we can't tweak the AF fine adjust for lens AND distance.

11-15-2013, 08:45 AM	#22
JinDesu Veteran Member Join Date: Jun 2011 Location: New York City Photos: Gallery Posts: 5,638	Originally posted by devorama Okay, so upon further testing in tungsten light, I've found my DA70 needs about a +2 correction at close distance of about 5 feet and about a -2 correction at larger distances like 12 feet. I guess I can split the difference and set it to 0 correction. Or adjust on the fly based on distance... Hmm... Too bad we can't tweak the AF fine adjust for lens AND distance. Hello, Sigma dock! If only every manufacturer was nice like Sigma.

11-15-2013, 08:51 AM	#23
devorama Veteran Member Join Date: Apr 2009 Location: Chicago, IL Photos: Gallery \| Albums Posts: 638	Originally posted by JinDesu Hello, Sigma dock! If only every manufacturer was nice like Sigma. Except there is no Pentax version of the sigma dock! :-(

11-15-2013, 08:52 AM	#24
JinDesu Veteran Member Join Date: Jun 2011 Location: New York City Photos: Gallery Posts: 5,638	Originally posted by devorama Except there is no Pentax version of the sigma dock! :-( Well yes they can be nicer

11-15-2013, 12:54 PM	#25
bxf Veteran Member Join Date: Jul 2010 Location: Lisbon area Posts: 1,660	Originally posted by devorama Okay, so upon further testing in tungsten light, I've found my DA70 needs about a +2 correction at close distance of about 5 feet and about a -2 correction at larger distances like 12 feet. I guess I can split the difference and set it to 0 correction. Or adjust on the fly based on distance... Hmm... Too bad we can't tweak the AF fine adjust for lens AND distance. You forgot to include different settings for the various focal lengths of a zoom. Wayyy too many permutations/combinations, though ideally, that's exactly what is required.

11-15-2013, 02:48 PM	#26
devorama Veteran Member Join Date: Apr 2009 Location: Chicago, IL Photos: Gallery \| Albums Posts: 638	Originally posted by bxf You forgot to include different settings for the various focal lengths of a zoom. Wayyy too many permutations/combinations, though ideally, that's exactly what is required. It is possible though. The Olympus OM-D E-M1 has not only the focus adjustment per lens, but also individually for each of its 37 phase detect sensors. And for zoom lenses, you can calibrate it at the both ends of the zoom range. This is the kind of thing that should be absolutely possible with modern hardware. Wouldn't it be awesome if Pentax would allow such things in a firmware update? In my case, it's not even a matter of focal length, since it's a prime lens. I'd just like it to be adjustable for focus distance.

03-19-2014, 06:12 AM	#27
ALiEN\|PoV Junior Member Join Date: Sep 2013 Location: Hey! Click. Photos: Albums Posts: 38	Originally posted by devorama It is possible though. The Olympus OM-D E-M1 has not only the focus adjustment per lens, but also individually for each of its 37 phase detect sensors. And for zoom lenses, you can calibrate it at the both ends of the zoom range. This is the kind of thing that should be absolutely possible with modern hardware. Wouldn't it be awesome if Pentax would allow such things in a firmware update? In my case, it's not even a matter of focal length, since it's a prime lens. I'd just like it to be adjustable for focus distance. Slightly old thread, but still relevant. IF I recall correctly you can store 20? individual lens adjustments. I guess space is the problem, as the adjustments are maintained even without a battery connected. However, with 2 SD cards and the the overall speed; I'd say you could store adjustments on a SD card. This would allow for way more complex AF adjustments, like focal + Aperture + Tungsten, or focal + Aperture + Daylight. (theoretically). And so on etc. I'd link it with global adjustments, so the lens connected would be controlled by this preset. Obviously, the access speed of the SD might be a factor. Adjustment linked Aperture might induce AF lag, but you could always have the option to unlink it.