[Guest]

Are the sensors used for PDAF less noisy than the ones used to capture the image? Larger pixels in the former? Or what is the problem?


Noticed that before - many PD mirror less switch to contrast AF in low light :o

 

Interesting point. Would make sense that there is a sensitivity issue. All the PDAF-on-sensors I have seen are single pixels. If the signal to noise ration becomes too low, it won't work reliably anymore. In contrast detect, the camera can analyse a bigger area, and thereby also some of the noise can be averaged out. On the other hand, it should be possible to sample the single PD pixels multiple times and average out the noise as well. I don't know if there is a technical obstacle to the latter concept.

 

How big are the regular PD sensors? They are linear sensors, and look fairly big in these images (compared to the wires that lead the signal off the chip).

 

http://www.the-digital-picture.com/photo...ained.aspx

http://www.imaging-resource.com/PRODS/E7...NSOR-L.JPG