I think the problem with your suggested AF sensor layout is for any kind of tracking shooting, the points would be way too spread out to keep anything close to consistent focus on the same object.

I don't think so. I don't know of a single person that uses every AF point for tracking. You select one point, stick it on your object, and keep it on your object. One point is one point - it doesn't matter where it is in the frame.

ecarr said on September 29, 2008:

Think folks that are aware of the rules of 3 will figure it out, regardless of what AF system is in play. Some cameras are obviously easier for this purpose than others.

But that's the thing: the AF points are the same as they are on the 5D, and they're pretty useless. Only the far left and right one come close to "rule of thirds" use, and they pretty much stink in low light situations. So if they've had three years to figure it out already and haven't been able to make it work, I doubt three more will do much good.

ecarr said on September 29, 2008:

But I also don't understand the complexities in extending an existing AF system with cross-point. Guessing 3 years is enough time.

Especially given the 9 cross-type AF points on the cheaper 50D… which uses basically the same AF point layout.

If all you shoot is the center point, the 5d Mk II should be pretty strong with the hidden AF points especially. But if you are going for rule of 3 shots, I agree, it will be a lot more challenging.

Think folks that are aware of the rules of 3 will figure it out, regardless of what AF system is in play. Some cameras are obviously easier for this purpose than others.

I don't get the lack of cross-point sensors more than the sensor layout. But I also don't understand the complexities in extending an existing AF system with cross-point. Guessing 3 years is enough time ... Wondering what the end Canon engineering tradeoff decisions were for what features were in / out ...