CD 'optimized' lenses
I read a lot about 'contrast detect AF optimized lenses'. What does it mean for lens? Camera tells the lens where to focus, so its important for camera if it is CD or PD, and lens does only what camera tells the lens to do. What am i missing?
CDAF has to estimate where the best focus is by taking several measurements around that point, whereas PDAF, once it is close enough, can locate the best focus from a single measurement. Hence the dynamics of the lens' focusing mechanism for optimum performance are slightly different between the two systems.