Canon has posted a firmware update for its EOS-1D Mark IV and EOS-1Ds Mark III full-frame DSLRs to allow them to work correctly with the new EF 200-400mm F4 L IS 1.4x lens. Firmware versions 1.1.3 (1D Mark IV) and 1.2.2 (1Ds Mark III) allow the cameras' central AF points to achieve focus with the lens when it is used with an extender, where the combined aperture is F8. Both updates are available for immediate download. 

Firmware version 1.1.3 for Canon EOS-1D Mark IV

Firmware Version 1.1.3 for the Canon EOS-1D Mark IV camera incorporates the following functional improvements and fix:

  • Enables the center AF point to autofocus when the camera is used with the EF 200-400mm f/4L IS USM Extender 1.4x lens and an Extender, whose combined maximum aperture is f/8.
  • Fixes a phenomenon in which abnormal images may result when continuous shooting mode is enabled and the image size is set to "RAW" or "RAW+JPEG".

Firmware version 1.2.2 for Canon EOS-1Ds Mark III

Firmware Version 1.2.2 for the Canon EOS-1Ds Mark III camera incorporates the following functional improvement:

  • Enables the center AF point to autofocus when the camera is used with the EF 200-400mm f/4L IS USM Extender 1.4X lens and an Extender, whose combined maximum aperture is f/8.
  • Firmware Version 1.2.2 is for cameras with firmware version 1.2.0 or earlier. If your camera’s firmware is already Version 1.2.2, it is not necessary to update the firmware.