juckerz wrote in post #16147167
That's the dumbest thing I've read all day, and I was just on a NASCAR forum. These two cameras most certainly do not use the same implementation of 'AI Servo II AF'. Tracking algorithms are created for specific bodies based on the number and sensitivity of the focus points. So an algorithm for a 45 focus point 1D body isn't going to be the same as one created for the 7D's 19 points (or any subset of those points),,, now is it? Duh.
1D II, III, & IV bodies all murder the 7D in tracking accuracy and focus speed.
You are obviously entitled to your opinion, but you are also obviously ignorant on how software works. 5 point AF, 20 point AF or 100 point AF, the same software can work, just with a larger array of data to pass focus to. I also have used multiple 1D3s, 1D4, and multiple 7Ds, and I know very, very well how they all compare.
Bottom line, the 7D and 1D4 both use dual digic iv processors with a separate dedicated AF processor, and both employ AI Servo II algorithms. Sure, there might be some tweaks and setting adjustments to the 1D4, but basically, the same platform. # of AF points and their types are nothing more than configuration data in the firmware. So perhaps my post wasn't the dumbest one out there, and you can go back to the Nascar forums.
More learning grasshopper, less attacking...
From Canon wrote:
Like all EOS-1 series models, and the EOS 7D, the EOS-1D Mark IV features a dedicated autofocus microprocessor for handling AF calculations. To cope with AI Servo running at 10fps, the autofocus processor shares this processing with the camera processor, thereby improving the speed of AF calculations.
The autofocus algorithm has also been adjusted based on user feedback. The EOS-1D Mark IV has a more balanced response that has been tuned to offer a more stable autofocus operation.
AI Servo II autofocus functions in a similar way to the system found in the EOS 7D – when tracking a moving subject it will predict where the subject should be based on current trajectory and speed. If the camera obtains an autofocus reading that is substantially different to what is expected, it will ignore that reading and continue to the next predicted position. This also works effectively when an obstacle passes in front of the main subject. In this instance, the camera will continue to track the main subject basing the focus on the results calculated immediately before the obstacle passed between the camera and the subject. The changes in the autofocus system and algorithm mean that AI Servo II AF can now be used accurately with close-up subjects as well.