The other major improvement for the EOS-1D Mk IV is the new 45-point autofocus system, which features 39 of the more sensitive and accurate cross-type sensors, which unusually are positioned around the outside of the focus area, with the six conventional strip-type sensors in a line across the middle of the frame. I was able to try the AF system briefly with a couple of different lenses, and I can confirm that it is extremely fast, the tracking function works superbly and it appears to have no problem even when focusing on dark low contrast subjects through a 400mm telephoto lens. It would probably take fairly specialised equipment to determine if it's faster than Nikon's much-praised 51-point Multicam AF system, but suffice it to say that it is certainly fast enough for even the most demanding professional.
The EOS-1D Mk IV is the latest digital SLR to feature HD video recording. It uses the same system as the popular EOS 5D Mk II, with full 1080p video at a range of different frame rates. It can record stereo audio via an optional external microphone, and can play back on a HDTV via its HDMI output jack. It can also shoot at 720p or VGA resolutions at higher frame rates for slow motion effects. Like the 5D Mk II it also allows full manual exposure control while filming, providing creative options such as control over depth of field.
Until I can get a production EOS-1D Mk IV in for a full review in a couple of months (and how I'm looking forward to that!) I can't say anything about the image quality, or indeed anything more about performance, so I hope this preview will be enough to whet your appetite. Between this camera, the EOS 5D Mk II and the EOS 7D that I'll be reviewing next week, the second half of 2009 is looking pretty good for Canon digital cameras.