Sigma/Nikon AF outer focus points problem?

Joined
Feb 22, 2011
Messages
143
Location
California
Has anyone noticed a tendency for Sigma lenses older than those made in 2012 having an issue with back-focusing on Nikon's 39-point and 51-point DX sensor AF systems? I have two very nice, very sharp Sigma lenses, the 70-200mm f2.8 OS HSM and the 30mm f1.4 HSM, and both of these back-focus on any AF point EXCEPT the center one, on my D7100 AND my D300 bodies. I do have a new Sigma 17-50mm f2.8 OS HSM which nails the focus with ANY AF point on either of my two camera bodies however, and two Nikon lenses (35mm f1.8G and 50mm f1.8D) which also perform well.

I've been working around this by shooting with only the center point, but that means I cannot use the multi-point or automatic AF modes at all, which is a little frustrating. Has anyone else seen results like this shooting wider aperture lenses on outer AF points?
 
Joined
Jan 2, 2012
Messages
6,531
Location
British Columbia
I'm fond of my 2010 Sigma 18-250 and it's not displaying any focal oddities.
Sometimes resetting your cam back to default and re-doing minor adjustments may solve lots of problems.
Here's a shot at 18mm.

Subscribe to see EXIF info for this image (if available)
 
Joined
May 16, 2006
Messages
9,081
Location
Oregon
I have the Sigma 18-250 OS Macro (2012 version) and all of the focus points including live view work fine on my D7K.
 
Joined
Feb 22, 2011
Messages
143
Location
California
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I think this is only a problem on f2.8 and wider lenses with the CAM3500 51-point AF system. I have CRIS Camera checking on this for me.

Check today reveals that the 17-50mm f2.8 OS HSM also does this, but to a lesser degree which can be correctly mostly with AF Fine Tune. Very strange that I get the same results on two different Nikons made more than 5 years apart though.
 
Joined
Feb 22, 2011
Messages
143
Location
California
  • Thread Starter Thread Starter
  • #5
I checked in with CRIS Camera in Chandler, AZ on Thursday. They're a Nikon Service Center and a Sigma warranty center. They checked the serial number on the 30mm f1.4 lens and confirmed that it has the latest software in it. We also checked with their test chart and that Dirty Thirty works just fine on my D300, exhibiting a small amount of field curvature but still essentially focusing on the outer points when the center focus point is pulled forward to -6 with AF Fine Tune. The 30mm will not focus correctly at all on the D7100 even with the AFT pulled to -18. It still back focuses or misfocuses. Steve the lead technician there said it is likely a lens-body miscommunication error between the two and that Sigma doesn't have an update for the lens software yet. He also said that Nikon won't allow him to work on a D7100, D600, or D800 under warranty yet.

Does anyone want a good deal on a Sigma 30mm f1.4 lens that I can't use? If I can't shoot it on my bestest, newest body, I'm not keeping it around. I can shoot my Nikon 35mm f1.5G and get nearly the same result with no outer AF point issues.
 

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