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.