To Users of the EF 200-400mm f/4L IS USM Extender 1.4x Interchangeable Lens for Digital SLR and Mirrorless Cameras
Thank you for using Canon products.
We have determined that some units of the EF 200-400mm f/4L IS USM Ext. 1.4x interchangeable lens for digital SLR and mirrorless cameras exhibit a phenomenon in which the focus may not be achieved during AF shooting. Firmware which addresses this phenomenon is available for download below.
We would like to offer our sincere apologies to users who have been inconvenienced by this issue. Going forward, we will spare no effort in our quality management to make sure our customers can use our products with confidence.
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.
EF 200-400mm f/4L IS USM Extender 1.4x lenses with Firmware Version 1.0.0 are affected.
(The firmware version of the lens can be checked from the camera’s menu.)
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 and perform the lens' firmware update using the camera.
*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
*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