Speedlight AF-assist causing back focus. Has anyone ever heard of a case where this has been fixed?

Started Dec 1, 2013 | Discussions thread
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Trazan Regular Member • Posts: 127
Speedlight AF-assist causing back focus. Has anyone ever heard of a case where this has been fixed?

Just got myself a D800 and an SB-910. Wonderful camera btw....I came from a D100 so it was about time

I tried the camera with the SB-910 and noticed that some shots were consistently out of focus, especially with my 24/1.4 lens but also other fast lenses. Used the center focus point only, which makes it easy to quiclky magnify the point of interest on the D800.

After some problem seeking I found the reason for this malfocus to be the AF-assist on the SB-910. If I turned this off, the D800 would focus fine. Turn it on, and the camera would back focus. Every time. Cover up the AF-assist light...the camera would still malfocus.

So I searched and found others with the same issue:

http://www.dpreview.com/forums/post/35695457
http://www.dpreview.com/forums/thread/3043213#forum-post-39038948
http://nikonrumors.com/forum/topic.php?id=3942

Searching some more, it seems it's not necessarily a Nikon issue:

http://photography-on-the.net/forum/showthread.php?t=1153480
http://photography-on-the.net/forum/showthread.php?t=1030333

I contacted my dealer and was told to send in my camera and speedlight to be checked. However, I've not found one single post on this internet thingy that suggest it's an issue that can be fixed. IF it can be fixed I'll gladly send in my SB-910 (I'm convinced it's a speedlight thing, and not the D800), but until then I'll just disable the AF-assist.

Soooo....does anyone have a clue as to why speedlight AF-assist causes malfocus? And whether the SB-910 can be fixed or echanged for another unit without this issue?

 Trazan's gear list:Trazan's gear list
Nikon D800 Nikon AF-S Nikkor 70-200mm f/2.8G ED VR II Nikon AF Nikkor 50mm f/1.8D Nikon AF-S Nikkor 24mm f/1.4G ED Tamron SP 90mm F2.8 Di VC USD 1:1 Macro (F004)
Nikon D100 Nikon D800
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