Even though we ARE Nikon lovers,we are NOT affiliated with Nikon Corp. in any way.

English German French

Sign up Login
Home Forums Articles Galleries Recent Photos Contest Help Search News Workshops Shop Upgrade Membership Recommended
members
All members Wiki Contests Vouchers Apps Newsletter THE NIKONIAN™ Magazines Podcasts Fundraising

Early report of D800 user AF issue

volvoswede

boise, US
54 posts

Click to send email to this author Click to send private message to this author
volvoswede Silver Member Nikonian since 04th Oct 2009
Fri 30-Mar-12 12:27 PM

Here's the first report I've seen of a D800 AF issue, it bears watching for me in the pre-order stage.

http://blog.mingthein.com/2012/03/30/update-on-nikon-d800-focusing-issues/

Visit my Nikonians gallery.

mdonovan

Mahwah, US
321 posts

Click to send email to this author Click to send private message to this author

#1. "RE: Early report of D800 user AF issue" | In response to Reply # 0

mdonovan Gold Member Charter Member
Fri 30-Mar-12 10:45 AM

Very interesting ... And somewhat concerning read. I would love for someone to make a post on how to test for this!! We amateurs rarely get as technical as adjusting focus per lens!
___________________________________________________________

Reality is merely an illusion, albeit a very persistent one. - A. Einstein

Visit my Nikonians gallery.

MotoMannequin

Livermore, CA, US
8582 posts

Click to send email to this author Click to send private message to this authorClick to send message via AOL IM

#2. "RE: Early report of D800 user AF issue" | In response to Reply # 0

MotoMannequin Awarded for his extraordinary skills in landscape and wildlife photography Registered since 11th Jan 2006
Fri 30-Mar-12 02:18 PM | edited Fri 30-Mar-12 02:20 PM by MotoMannequin

One great thing about Live View cameras is that you have 2 completely independent autofocus systems. This offers the possibility to use one as a diagnostic tool for the other.

The conventional (phase detect) AF sits in the top of the prism and focuses from the image reflected off the mirror. It's critical that the light path from the mount, off the mirror, and up into the phase detect sensor is exactly the same distance as the mount to the sensor, otherwise this AF will not operate properly. Most cameras have an offset screw to fine-tune the position of the mirror at rest, and misalignment of this screw, skewing the distance light travels to the AF sensor, is the typical cause of AF problems.

With Live View the camera now offers a contrast detect AF that uses data directly off the sensor. Because this is exactly the same image recorded during exposure, there is a lot less that can go wrong.

Bear in mind that contrast detect AF (LiveView) is optimized for accuracy, while phase detect AF (traditional) is optimized for speed. Contrast detect AF will therefore give more consistent results, and by its nature phase detect, even when working properly, will always be a little bit hit-or-miss. But, if phase detect AF is consistently off and contrast detect AF is always on, that's a good indicator there's no problem with the lens, mount, or sensor. Comparing the two is how you can isolate a problem to exist (or not) in the phase detect AF system.

Larry - a Bay Area Nikonian
My Nikonians gallery

www.tempered-light.com

rplst8

Johnstown, US
150 posts

Click to send email to this author Click to send private message to this author

#3. "RE: Early report of D800 user AF issue" | In response to Reply # 0

rplst8 Silver Member Nikonian since 18th Dec 2008
Fri 30-Mar-12 02:21 PM

How is it possible that the AF sensor is causing "a soft left side".

That sounds like a mount yaw alignment problem to me.

--
RL

Visit my Nikonians gallery and my Flickr page.

JosephK

Seattle, WA, US
7064 posts

Click to send email to this author Click to send private message to this author

#4. "RE: Early report of D800 user AF issue" | In response to Reply # 3

JosephK Silver Member Fellow Ribbon awarded for his excellent and frequent contributions and sharing his in-depth knowledge and experience with the community in the Nikonians spirit. Nikonian since 17th Apr 2006
Sat 31-Mar-12 03:11 AM

I, too, was wondering that.

---------+---------+---------+---------+
Joseph K
Seattle, WA, USA

D700, D200, D70S, 24-70mm f/2.8, VR 70-200mm f/2.8 II, 50mm f/1.4 D,
17-55mm f/2.8 DX, 70-300mm f/4.5-5.6 VR, 18-70mm f/3.5-4.5 DX

Ferguson

Cape Coral, US
5696 posts

Click to send email to this author Click to send private message to this author

#5. "RE: Early report of D800 user AF issue" | In response to Reply # 3

Ferguson Silver Member Fellow Ribbon awarded for the generous sharing of his high level expertise in the spirit of Nikonians Nikonian since 19th Aug 2004
Sat 31-Mar-12 10:10 AM

>How is it possible that the AF sensor is causing "a soft
>left side".

I don't have the problem but I read that as saying "if the AF point is on the left side the focus is soft, if the AF point is not the focus is sharp" meaning that the AF sensor was not in some fashion parallel to the primary sensor plane.

Comments welcomed on pictures: Http://captivephotons.com

mwhals

Winfield, US
1664 posts

Click to send email to this author Click to send private message to this author

#6. "RE: Early report of D800 user AF issue" | In response to Reply # 0

mwhals Silver Member Nikonian since 18th Apr 2004
Fri 30-Mar-12 02:49 PM

Reading down the comments, Nikon found a problem with the AF sensor in the camera and are sending him a new camera.

I am not concerned. It is one problem (that was not a design issue) out of how many cameras? I am sure it was lots of cameras.

Shoot nature with respect and don't trample it or startle its inhabitants. :)

Robman3

West of Santa Monica, US
1842 posts

Click to send email to this author Click to send private message to this author

#7. "RE: Early report of D800 user AF issue" | In response to Reply # 0

Robman3 Registered since 12th Apr 2010
Sat 31-Mar-12 05:23 AM

Haven't read that thread but the answer above about misaligned prism and sensor read, makes the trip to Nikon a 30 minute drive if this happens to the D800 once I pick it up.

Also, the Camera shop is a 15 minute ride.

Thanks for the heads up!

Rob

Visit my Nikonians gallery.

Visit my Nikonians gallery.

Visit my Nikonians gallery.

G