Anyone here with a D700 + SB-700 experiencing Back-focus when using AF assist?

[MomentCapture]

Hi Folks

I'm having an issue with back-focus when AF assist is enabled on my flash.
Covering the AF beam with my hand still produces back-focus, but when the AF assist beam is disabled on the flash I get perfect focus pretty much every time.
So as the beam itself doesn't appear to be the issue, it seems to me that the likely culprit maybe a firmware bug.

This wouldn't be an issue normally as I can focus fine in dim light, but if a room is too dim then I would need AF assist.

This issue seems to be mainly affecting fast primes due to the shallow DOF, for instance this back focus is more visible on my Nikon 85mm wide open.

Nikon are telling me this is not a recognised issue but it seems other people are experiencing this issue, with the D700, D3, D3s, SB-700 & SB-900 being affected.

http://forums.dpreview.com/forums/read.asp?forum=1021&message=35695457

http://nikonrumors.com/forum/topic.php?id=3942

http://www.ephoto.sk/forum/9/7979/nikon-af-assist-sb-900-700-sposobuje-backfocus-na-d700/

http://forums.dpreview.com/forums/readflat.asp?forum=1021&message=30389585&changemode=1

 

[jpw]

No issues here, I rarely use the AF assist but just checked with both my SB700 and SB900 on my D700 with the 24-120 F4 @ 120mm (similar DOF to your 85 wide open) - makes no difference whether it's on or off.

 

[MomentCapture]

Can anyone test this with a fast prime like an 85, as apparently the problem seems allot more pronounced in primes, especially with the outer focus points.