Sigma issued a warning for some recently released telephoto lenses that may have an autofocus problem.
- APO 50-500mm F4.5-6.3DG OS HSM
- Serial Numbers between 10633051 and 10972000
- APO 120-400mm F4.5-5.6 DG OS HSM
- Serial Numbers between 10574001 and 10972000
- APO 150-500mm F5-6.3 DG OS HSM
- Serial Numbers between 10674301 and 10972000
The serial numbers are listed on thier site and they are offering free repair if you are experiencing problems.