Canon EOS-1D X Mark III EOS-1DX Mark III Advanced User Guide - Page 895

The AF point is blinking or two AF points are displayed. See Selecting the AF Area and AF Point (Viewfinder Shooting) for details on AF point blinking or illumination when the < > button is pressed. AF points in registered positions are blinking ( , ). Manually selected AF points (or zones) and registered AF points are displayed ( , ). I cannot lock the focus and recompose the shot. Set the AF operation to One-Shot AF ( ). Shooting with the focus locked is not possible with AI Servo AF/Servo AF ( ). The continuous shooting speed is slow. High-speed continuous shooting may be slower depending on the type of power used, the battery level, ambient temperature, ISO speed, flicker reduction, shutter speed, aperture value, state of the aperture during continuous shooting, subject conditions, brightness, type of lens, use of flash, shooting function settings, and other conditions. For details, see Selecting the Drive Mode. The maximum burst during continuous shooting is lower. If you shoot a subject that has fine detail such as a field of grass, the file size will be larger, and the actual maximum burst may be lower than the number listed in Performance Data. Even after I change the card, the maximum burst displayed for continuous shooting does not change. Estimated maximum burst indicated in the viewfinder does not change when you switch cards, even if you switch to a high-speed card. The maximum burst shown in the table in Performance Data is based on the standard Canon test card, so the faster the card's writing speed, the higher the actual maximum burst will be. For this reason, estimated maximum burst as indicated in the viewfinder may differ from actual maximum burst. ISO speeds cannot be selected for still photo shooting. The minimum speed in the ISO speed range is ISO 200 when [ : Highlight tone priority] is set to [Enable] or [Enhanced]. 895