Canon 5D Mark III update to unlock high-end HDMI video

Videographers will get better color from Canon's high-end SLR with an update coming in 2013. Also: an autofocus improvement for supertelephoto fans.

Canon's EOS 5D Mark III
Sarah Tew/CNET

Canon plans to release a notable firmware update to its high-end EOS 5D Mark III in April that will let videographers use the SLR to record uncompressed HDMI video.

As the successor to the 5D Mark II that jump-started the video SLR revolution four years ago, the 22-megapixel 5D3 has big shoes to fill. The new update surely will help professionals who need better quality, even if ordinary folks need not care much. Here's what Canon had to say about the news:

When shooting video, HDMI Output makes possible the recording of high-definition uncompressed video data (YCbCr 4:2:2, 8 bit) from the EOS 5D Mark III to an external recorder via the camera's HDMI terminal. This, in turn, facilitates the editing of video data with minimal image degradation for greater on-site workflow efficiency during motion picture and video productions. Additionally, video being captured can be displayed on an external monitor, enabling real-time, on-site monitoring of high-definition video during shooting.

If you're not familiar with the mumbo-jumbo, 4:2:2 refers to the camera's "chroma subsampling" behavior, and it's a significant step up from the 5D Mark III's current firmware, which compresses video down to 4:2:0 for HDMI output.

Videocameras capture both color and brightness information, but typically don't capture color information for every pixel. Moving from 4:2:0 to 4:2:2 means the camera records color information for twice as many pixels. (Adobe Systems has a good explanation of chroma subsampling if you're curious.)

The 4:2:2 rate means the 5D3 can be used to record higher-resolution color information with an external recording device. That's useful for situations such cinema usage where editors expect to adjust the colors through color grading.

It's also a competitive step up. Nikon's D4 and D800 SLRs can output uncompressed 4:2:2 video via HDMI.

Note that the announced improvement only is for those recording video via HDMI Output with an external recording device, meaning they're not available for people recording video on a flash card.

"We cannot discuss future plans, but the current codecs in use on the 5D Mark III do not support 4:2:2 color sampling," said spokesman Kevin McCarthy. Codecs are video and audio compression technologies, and the 5D Mark II and 5D Mark III use the H.264 codec.

Canon also said the firmware will improve the camera's autofocus.

Currently, the camera can autofocus with a lens with an aperture of f5.6 or wider. That means that Canon's 100-400mm zoom lens will autofocus at 400mm and its widest setting of f5.6, but if you mount it to a 1.4x teleconverter to extend to 560mm and f8, autofocus will stop working.

The new firmware will enable autofocus with this f8 minimum aperture, though. That's something that's been present only on Canon's higher-end EOS-1D SLRs.