D800 AF "issue": some details...

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D800 AF "issue": some details...

Postby AA2 » Sat 28 Jul 2012 20:22

The so called "D800 AF issue", -if real- and after lots of internal communication is mainly the result of a faulty alignment between the AF sensor and the secondary mirror. Technically the repair of the faulty alignment is called a yaw and pitch alignment.
This faulty alignment between AF sensor and secondary mirror can be perfectly recalibrated though.

This problem, -which exists on several D800 bodies-, is very probably the result of a rush to send out D800 bodies and kits.
Unfortunately for Nikon the whole issue is blown out of proportion by several websites sometimes just because it is a hot topic and it generates clicks. :cry:
Because of the hysteria about this on a number of websites, some people who have a perfect camera start to think they might have a defective one. This is a drama for some Nikon repair centers and Nikon dealers because of the extremely time consuming discussions.
Further more, expectations of some users, -also professionals- are sometimes not realistic. Real professionals are using whether live view or manual focus to achieve critical sharpness, and not only with outer AF points. Up to that the outer D800 AF sensors only react on horizontal contrast, not on vertical, which might result in user errors and false conclusions.
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Re: D800 AF "issue": some details...

Postby pam.meier » Sun 5 Aug 2012 07:32

Nikon deserves to have this issue blown out of proportion. It is their own fault as they weren´t trying to prevent the chaos.
At first they should have issued a statement what exactly happened and reassure buyers that their AF alignment problem will be fixed - even out of warranty and without any cost (I´ll have to send in and insure my camera myself - not good!).
Then they should have issued a statement when the production problem was fixed and what serial numbers will not be affected.

Sorry, folks, but to me this is a very serious case and Nikon did not act as professionally as I expected them. Note: this is my personal opinion, very emotional, as I am mad with them, I supposedly have the best camera sitting at home and cannot use my main zoom lens since 3 months. I cannot use Live View at event photography! The reports I´m getting for Düsseldorf not being able to calibrate and repair the AF misalignment even till mid of July are plain disappointing.
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AA2, please...

Postby Stany Buyle » Tue 7 Aug 2012 09:50

...advice about how to test correctly the D800 AF accuracy.

And -if possible-, tell us more on what's real about the "D800 AF issue".

Thanks in advance.
Stany

PS: Apparently and after all I read on different websites I was very lucky to get 3 perfect D800's. Both my first and second D800(E) were perfect out of the box and after serious testing, the third one I purchased needed correction for what looked like back focus.

D800 related topics:
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Re: D800 AF "issue": some details...

Postby AA2 » Wed 8 Aug 2012 14:20

StanyB wrote:AA2, please advice about how to test correctly the D800 AF accuracy. And -if possible-, tell us more on what's real about the "D800 AF issue".
Thanks in advance. Stany


Dear Stany,

An excellent guide to test a D800’s autofocus, and a general explanation of the problem, is already available on the website of Thom Hogan:http://bythom.com/D800autofocus.htm
I agree with just about everything he writes on this subject. In general he follows the hypothesis that in some cameras yaw & pitch calibration is not done perfect, possibly in combination with wrong values programmed in the AF sensors.

Correct yaw & pitch calibration maintains the base of a good working Ph AF system.

1. About the AF testing method:
  • Thom Hogan’ test method is simple and good: set the camera parallel to a flat wall and place 3 test cards on 1 horizontal line: 1 for the left sensor, 1 for the central, and 1 for the right. The camera remains in the same position relative to the wall during the entire test. This is the same method we use as the last control step. But in general I’d say: follow the guidelines of the article by Thom Hogan. He has written a good explanation, I would say "no need to reinvent the wheel";-)”
Further… :
  • Re focus for every test shot.
  • Make every test shot 3 times with phase AF and once with LV-AF(to compare). “3 times with phase AF” because phase detection might give some variables within the Nikon AF tolerances. Ph AF was initially made for speed, although accuracy became excellent during years of evolution.
  • AF testing should be done on tripod, remote, with mirror up or exposure delay.

2. Wrong AF testing methods:
  • Handheld AF testing has no value at all.
  • Rotate the camera on its vertical axis during the test to aim at the same target with left, center and right AF point is a wrong AF test method, since the test card and the AF sensor are not parallel to each other.
Hope this helps,
Regards.
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Re: D800 AF "issue": some details...

Postby Stany Buyle » Thu 9 Aug 2012 21:37

Interesting video demonstrating a correct test for D800 AF issues.
(I found the link on Dpreview posted by Raul.)
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My D800 came back after AF calibration …

Postby pam.meier » Sun 16 Sep 2012 21:02

Details :D :D in this topic.
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Photokina 2012: Nikon talks about the D800's outer AF issue

Postby Stany Buyle » Sat 22 Sep 2012 00:33

Found underneath link on Dpreview.
http://falklumo.blogspot.de/2012/09/photokina-2012-nikon-talks-about-d800s.html
The technical details and "cause" are very similar to what AA2 explained here two months ago.
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D800 AF issue situation as seen by Thom Hogan

Postby DiederikVP » Fri 28 Sep 2012 14:10

From: http://www.bythom.com/
Thom Hogan wrote:D800: Where Do We Stand?
Sept 25, 2012--Some of you have noted I've been quiet about the D800 as of late. That's not because I haven't been...
moderator action: Quote waiting autorisation by Thom Hogan.
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The impact damage explanation by Nikon

Postby DiederikVP » Sun 17 Feb 2013 11:06

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Interesting test about D800 AF issue

Postby Stany Buyle » Mon 18 Feb 2013 08:51

http://hifivoice.wordpress.com/2012/09/02/d800-autofocus-the-grand-finale/
Marc Heijligers was one of the first D800 users who wrote interesting reports about the D800 AF issue and the related repair procedures in the Netherlands Nikon repair center.
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Re: D800 AF "issue": some details...

Postby Steve Bingham » Thu 21 Feb 2013 07:01

I have recently left dpreview.com because of the non-stop exaggeration of Nikon’s problems with the D600 and D800 (and because of the anonomity of the responders). Basically, Nikon has fixed the problems (although fairly recently). My D600 has NO dust, oil, or whatever on the sensor. It arrived clean as a whistle and still is. Will it get dusty in time? You bet – as will all DSLR camera sensors. This was a great post and I thank Stany for getting it going – and the others for adding to it. Shame on Nikon for not owning up to the problem – but congratulations on fixing both.
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Another AF fine tuning program for Nikon

Postby Stany Buyle » Wed 1 May 2013 21:45

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Dot-Tune autofocus tuning (link to youtube instruction movie

Postby DiederikVP » Fri 3 May 2013 09:09

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Ken Rockwell about AF fine tuning

Postby Stany Buyle » Sun 19 May 2013 18:27

Ken Rockwell wrote:15 May 2013, Wednesday
AF Fine Tune?
You don't need it; don't buy a new camera because you think it will get you sharper pictures.
I never use the AF Fine... read more


After long research on this problem I agree with KR' opnion on this matter. TMHO, if your camera back or front-focuses, send it in for repair to a Nikon service center. That's what I did a couple of times(D70, D200, D800) and related to two Nikon D800 bodies they came back with AF fine tune settings deleted and my cameras were autofocusing simply perfect.
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Link to AF test charts

Postby Stany Buyle » Mon 17 Jun 2013 22:31

kindest regards,

Stany
I like better one good shot in a day than 10 bad ones in a second...
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