Upload & Sell: On
I guess I still need to be educated as I thought I already had this all figured out. ...
This picture tells me that you can only use center-point AF on the XTi (400D) and only a lower-precision one-dimensional AF sensor? Not all 9 points are active at f5.6? Or is this actually how AF works on the 400D? I'm also surprised that this picture says that at f5.6 the 1DIII does not have an active cross point sensor? Again, this goes against what my thoughts were. Can someone un-wind my confusion?
I should have paid closer attention to the diagrams when I found that link, I guess. I am pretty sure the "High End" diagrams are showing the AF setup for the 1D Mark II, not the Mark III. As for it showing the XTi as only being able to use the center point at f5.6 I am not sure. If nobody else responds before I get home, I can test that with my wife's XTi...
I sent that link for the concepts more than the pictures.
And while I'm at it, I thought that now there are actually THREE types of AF sensors. I have an XSi (450D) and my interpretation of the AF sensor is that it has:
- 8 one-dimension AF sensors, effective to f5.6
- 1 cross type AF sensor shaped like a '+' at the center, effective to f5.6.
- The center AF sensor is "additionally sensitive" with lenses f2.8 or faster (meaning it is a cross sensor shaped like a '+' in combination with a cross sensor placed like an 'x')
What did I mix up in my interpretation?
Yes, some newer cameras have AF points that have additional diagonal sensitivity with fast lenses.