01-21-2012, 02:37 PM
[quote name='Klaus' timestamp='1327151644' post='15091']
You can, of course, detect the direction of focus with C-AF. Just take two AF readings and you got both direction as well as object speed. Accuracy is just a matter of frequency with is no magic either these days. Additionally C-AF can do real shape detection whereas P-AF remains comparatively stupid.
[/quote]
That means you can't. You have to do a lens movement inbetween. The speed and predictable qualities for phase detect is that you can see it right away.
On the two readings with just contrast detect AF: you can not determine speed. Neither can you with PD-AF. (And the speed has nothing to do with determining the direction of focus anyway, only with tracking focus). Only on paper you can. But in real, you need to know too much, too accurate about the lens in use. So in real, it always is a process of more steps.
You can, of course, detect the direction of focus with C-AF. Just take two AF readings and you got both direction as well as object speed. Accuracy is just a matter of frequency with is no magic either these days. Additionally C-AF can do real shape detection whereas P-AF remains comparatively stupid.
[/quote]
That means you can't. You have to do a lens movement inbetween. The speed and predictable qualities for phase detect is that you can see it right away.
On the two readings with just contrast detect AF: you can not determine speed. Neither can you with PD-AF. (And the speed has nothing to do with determining the direction of focus anyway, only with tracking focus). Only on paper you can. But in real, you need to know too much, too accurate about the lens in use. So in real, it always is a process of more steps.