Having just bought a Nikon D800, i decided to have a play with the 50mm 1.4G on it.

I noteced it was back-focusing by about 2cm so tweeked the AF fine-tune. however thats now maxed out at -20 and its not brough the focus close enough still.

Is there any way to manually adjust / calibrate either the lens and/or camera body without having to resort to sending them away?

  • \$\begingroup\$ Not much to add here except that my 50mm 1.4D autofocuses properly on the D800. Not sure what's up. \$\endgroup\$ Jul 15, 2012 at 2:07
  • \$\begingroup\$ 2 cm is a bit too much off to be still called "fine" tuning... \$\endgroup\$
    – Francesco
    Jul 15, 2012 at 10:12
  • \$\begingroup\$ at what focus distance was the lens backfocussing by 2cm? \$\endgroup\$
    – Matt Grum
    Jul 16, 2012 at 9:55
  • \$\begingroup\$ thats on a target at about 1m \$\endgroup\$ Jul 16, 2012 at 12:44

3 Answers 3


It turns out that the lens was actually at fault (i sent it back to Nikon)

I still cant understand quite how the lens can be wrong, surely when its in focus, its in focus?!

But thanks for your responses guys :-)


20mm out is a massive amount and not explicable by any normal calibration errors. If it is really back-focusing by 20mm (2cm) then something is faulty.
If the D800 is OK with other lenses it's liable to be the lens that is faulty.
BUT If the lens is OK with other cameras it's liable to be the camera.
BUT if both the above apply, which is how Murphy loves to work, then it does not make immediate sense.

Whatever the cause, it will very likely be worthwhile finding out what is causing it.


If your lens works fine with other cameras, this may be the notorious D800 autofocusing issue, which on some units affects autofocus sensors on one or both sides but not in the center. See the HIFIVOICE post for a detailed description of the issue and how to test for it - they also observed backfocusing by 2cm or more.


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