Canon's 2012 Cinema EOS DSLR — the world's first 4K DSLR, 18MP full-frame on the 1D X chassis.
The Canon EOS-1D C, announced in April 2012, was the world's first 4K-capable DSLR: an 18MP full-frame EF-mount body built on the EOS-1D X chassis but folded into the Cinema EOS family. It launched at a formidable £10,000-£12,000, roughly double the 1D X.
It records 4K (4096x2160) at 24/25p as 8-bit Motion JPEG to CF cards using an APS-H crop of the sensor, plus Full HD up to 60p from the full frame, with Canon Log gamma - the first EOS body to carry it. As a stills camera it is essentially a 1D X: 18MP, 61-point AF, 12fps, magnesium weather-sealed body. There is no built-in ND and contrast-detect live-view focus only, and enormous MJPEG file sizes.
Its significance is historical - it shot broadcast and feature work when 4K acquisition was rare, and it marks the origin point of Canon's hybrid stills/cinema line that leads to the R5 C.
On the used market, treat it first as a decade-old flagship DSLR: check the shutter count (rated 400,000; replacements are now a parts gamble), inspect the mirror box and focusing screen, and test both CF slots at 4K bitrates with fast UDMA-7 cards. Confirm Canon Log is present and the video modes record cleanly, since the 1D C's value over a plain 1D X rests entirely on that firmware - and beware 1D X bodies misdescribed as 1D Cs (the 1D C is marked on the body and reports its model in EXIF). Rubber grips and the port covers age badly, LP-E4N batteries need replacing, and any Err history on the top LCD warrants a walk-away.