The Canon EOS 1DX mark III features a newly designed 20.1MP full-frame CMOS sensor and updated DIGIC X image processor. The EOS 1DX mark III is capable of continuous shooting rates up to 16 fps with the optical viewfinder or 20 fps in live view, with an 1000-shot buffer when shooting raw+JPEG. Complementing this speed is an impressive native sensitivity range from ISO 100-102400, that can be expanded to ISO 50-819200, to suit working in a variety of lighting conditions. Also benefitting the speed is the EOS iTR AF X autofocus system, which uses 191 points for quickly and accurately acquiring focus. It also enables Face Tracking and Head Detection AF functions, which use Deep Learning Technology, to maintain critical focus on moving subjects. Additionally, when working in live view, Dual Pixel CMOS AF uses 3869 manually selectable points and provides a smooth, natural focusing quality akin to the way a camcorder acquires focus.

In addition to high performance stills shooting, the 1D X Mark III is also highly competent for video, with the ability to record DCI 4K content internally at up to 60 fps with 10-bit, 4:2:2 color, as well as Full HD at 120 fps and raw 5.5K (5472 x 2886) at 60 fps. Complementing recording is Movie Digital IS, manual focus peaking, and Focus Guide, and, also, Canon Log Gamma can be used for greater colour grading control in post.

Complementing the imaging capabilities is one of the key features of 1D-series cameras: a durable and robust body design. This camera uses a magnesium alloy construction that is weather-sealed to guard against dust and moisture for working in especially trying environments. The body also incorporates dual CFexpress memory card slots to support the fast-continuous shooting rates and high-resolution video capabilities. The optical pentaprism viewfinder is benefitted by an updated mirror drive mechanism for reduced blackout and the 3.2" 2.1m-dot touchscreen LCD is available for intuitive playback and menu navigation. Additionally, built-in Wi-Fi, Bluetooth, and GPS permit seamless wireless connectivity and a built-in Ethernet port allows for faster wired LAN file transferring.