Sigma Corporation is reporting autofocus defects with some of their recently produced lenses: the APO 50-500mm F4.5-6.3 DG OS HSM, APO 120-400mm F4.5-5.6 DG OS HSM and APO 150-500mm F5-6.3 DG OS HSM lenses.
The lens maker said the AF issue could possibly occur in some lenses within the following range of serial numbers:
SN 10633051 to 10972000 for APO 50-500mm F4.5-6.3 DG OS HSM
SN 10574001 to 10972000 for APO 120-400mm F4.5-5.6 DG OS HSM
SN 10674301 to 10972000 for APO 150-500mm F5-6.3 DG OS HSM
Sigma apologizes and offers their customers free inspection and modification free of charge through their service centers.
[Via: Sigma Japan]