We would like to ask you that, when using a Tamron lens with Canon EOS-1D X Mark II camera and Canon EOS 5D Mark IV, that has been released in April 2016, you turn OFF the “Lens aberration correction” function included in the camera’s menu prior to use. However, you can turn off the function only in Program modes (Creative Zone), i.e. Program AE, Shutter priority, Aperture priority, Manual exposure mode.