I love my sigma lenses.  They are fast and sharp, but every now and then they have to be calibrated. When you start to notice it missing focus then you need to either send it off to be calibrated or you can do it yourself!

These are the items you will need to do it yourself:

Camera with the sigma lens

The Sigma USB Dock found here. (about $60)

A Lens Focus Calibration Tool Card is helpful but not necessary. They are inexpensive and, in my opinion, worth it. If you don’t use one you will need an object that is high contrast you can focus on that will help you see where your focus is falling. 

A Tape Measure (optional if you have a lens focus card).

Patience!

Steps:

1.)    Now you are ready to set up your test scene.  Place the lens focusing card or object on a flat and level surface.  This can be the ground or a desk.  Then stretch out the tape measure. Make sure it is stretched out behind and in front of your focusing object.

2.)    Now you are ready to take your test photos. Set your camera to the widest aperture. This will help you determine where the focus is falling. Now take your test photos!  You will take one at 1 ft away, the next one at 2 ft, then around 6 ft and then beyond 6 ft.

3.)    Load your photos into light room or view them straight from your SD card. Zoom in to see where your focus is falling. 

4.)    Take your lens off the camera and attach it to the Sigma dock. It will check for the latest version of firmware.  If you need to update it now would be the time.  Then select the customization button.  Then you can click on focus setting button. And it will take you to a screen that looks like this:

Now you can adjust the focus forwards or backwards according to your needs. As you can see mine was tending to front focus, so I had to push the settings in the positive direction. Make your adjustments slowly and incrementally.  Then select the rewriting button. It will update the focus and now it is time to take your 4 test shots again.  The process starts over from here!

This can be tedious, but it is worth the effort to ensure your focus lands exactly where you want it to!  Check it on occasion to ensure that your lens is focusing correctly! Calibrating a zoom lens is a little different.  You can go to the video tutorial here by Sigma.

 Hope this is helpful! Thanks for reading!