Although almost identical externally, there are some key new features to convince you to buy/upgrade:
- Completely Redesigned 45-Point Autofocus System, with 39 high-precision cross-type focusing points
- Fast 10 fps Continuous Shooting
- 16-Megapixel Resolution
- Outstanding ISO Sensitivity (up to 102,400)
- Full HD Video Recording at Selectable Frame Rates
To accompany the new EOS-1D Mark IV Digital SLR camera, Canon is also announcing a new accessory, the WFT-E2 II A wireless file transmitter providing photographers with a wide range of professional digital connectivity options, details here.
Full press release here.
And Canon's micro-site here.
And their white-paper here.
As for me, I can't afford one, so I'll just upgrade my 'dream camera' from the Mk III to Mk IV version!!