Sigma 18-35mm F1.8 DC HSM "Art"
Sigma USB Dock
As mentioned before, the lens is compatible with Sigma's USB dock ($59.00 in the US), which allows you to connect the lens to the dock and fine tune specific settings on your computer, and by focal length or other parameter (such as focus limiting if that option is applicable to the lens). Additionally, you can check/update the firmware of the lens to make sure it is compliant with Sigma's latest improvements.
The control screen for the Sigma 18-35's focus setting looks like this:
As you can see, it offers you a significantly finer ability to adjust the AF setting than just the blanket adjustment that is applied to all focal lengths when you do so using Pentax's in-camera AF fine tuning. Because the Sigma 18-35 does not offer a focus limiter or custom function setting (like on Sigma's "Sport" lenses), this is the only adjustment you can make on this specific lens.
We'll be making a detailed post on how Sigma's dock works in the near future, so stay tuned for that!
