When using this lens with some camera models*1 and performing AF shooting from approximately 3m, the subject may not be in focus in some occasions.
*1 Camera models:
EOS-1D X Mark II, EOS-1D X, EOS-1D C, EOS 5Ds, EOS 5Ds R, EOS 5D Mark IV, EOS 5D Mark III
Customers who own one of the affected camera models above, or one of the cameras*2 that can be used for the lens' firmware update can download the latest firmware version and then perform the lens' firmware update using the camera.
The Firmware file can be downloaded from the link below:
*2 As of May 2018, the firmware update can be used for the following camera models listed below. Please note that EOS M camera models require an adapter EF-EOS M to connect to the EF 200-400mm f/4L IS USM Extender 1.4x lens:
EOS-1D X Mark II, EOS-1D X, EOS-1D C, EOS 5Ds, EOS 5DsR, EOS 5D Mark IV, EOS 5D Mark III, EOS 6D Mark II, EOS 6D, EOS 7D Mark II, EOS 80D, EOS 70D, EOS 800D, EOS 200D, EOS 750D, EOS 100D, EOS 650D, EOS M6, EOS M5, EOS M3, EOS M2, EOS M, EOS M100, EOS M50, EOS M10