Sigma has warned that the use of its Mount Converter MC-11 and certain Sigma zoom lenses with the Sony a9 may result in missed focus. According to a notice recently published by Sigma, the issue may arise 'occasionally' when using AF-S mode and while shooting 'in the telephoto range.'

The phenomenon, according to Sigma, affects both the EF-E and SA-E versions of the MC-11. The company says it is investigating the issue and that it will publish an update 'shortly,' presumably with a software fix in the pipeline.

Via: Sigma Photo