sure the lens is connected to the camera and turn it on-Set the aperture to f1.4-Press the menu button-Go to Setup Menu > AF-Fine Tune-Turn on AF fine-tune (on/off)-Experiment with the "Saved value"

I spent almost 4 hours fine-tuning, testing, and re-testing the lens today and I believe I can finally say I am keeping a Sigma lens.

Sigma sells a USB dock (about $59), but I usually used the on-camera auto-focus fine tuning settings to fix issues

I had to return the first lens that I got because changing the AF fine tuning value fixed the issue for f1.4, but made it worse for f2.8 and above

This focusing aid (the SypderLensCal) was and is good for LONG- DISTANCE auto-focus fine tuning.

not ALL the writings I found about this lens required AF fine-tuning.

After spending many hours re-doing and re-re-doing the settings on the lens with WILDLY varying settings according to each fine-tuning session, I finally called Sigma and asked them what (if anything) I was doing wrong

(All of which this lens handles wonderfully well!)Summing it up... once you fine-tune this lens, it lives up to it's hype 100%

(All with a zero auto-focus fine-tuning on my camera

better.==============Final Update 9/5/2015==============A word about the auto-focus fine-tuning on this lens.

Having said that... if you're not up for doing AF fine-tuning yourself, you can buy one and have Sigma do it for you.

Having said that... if you haven't learned to use your camera's AF fine-tuning (pretty much all DSLR makers have this in their cameras), then you really, really, REALLY should learn how.

At the time, I figured I was facing an auto-focus fine tuning issue

The (free) software that uses the dock allows you to make auto-focus fine-tuning changes at - on a prime lens - four different distances