From Sigma:
Thank you for your patronage to SIGMA products.
We would like to announce that we are planning to release a firmware update for the SIGMA 150-600mm F5-6.3 DG OS HSM | Sports in Canon and Nikon mount, as well as the SIGMA 150-600mm F5-6.3 DG OS HSM | Contemporary in Canon and Nikon mount on Friday, March 11th, 2016.
The latest firmware update improves the AF algorithm of 150-600mm F5-6.3 DG OS HSM lenses and further enhances AF speed by optimizing HSM (Hyper Sonic Motor) drive control.
It is expected to increase autofocus speed by approximately 20%, to a maximum of 50%, during normal shooting as well as when using “Speed Priority” set through SIGMA Optimization Pro.
The firmware update requires the installation of the latest version of SIGMA Optimization Pro on your personal computer and the SIGMA USB DOCK accessory (sold separately).
Further details on this firmware update will be announced at a later date.
We appreciate your continued support for our company and products.
B&H carries the Sigma 150-600mm lenses and the USB Dock.