Does anyone know if the sigma usb dock (soon to be released) will be compatible with older lenses? I have a 24-70 f2.8 that is front focusing. If I could use this dock to recalibrate it it would be great!
No, it won't be compatible with the previous generation of Sigma lenses.
All lenses Sigma designs going forward including the 3 new ones just released will be compatible with the USB dock.