Started Aug 21, 2012 | Discussions thread
random78 Regular Member • Posts: 284
Re: PDAF vs CDAF on NEX?

Let me first address your comment about out of focus shots with NEX, and the camera focusing on background instead of the subject. That can happen with any AF technology and its not a question of CDAF vs PDAF. The cameras really have no idea of what part of the scene is your intended subject. Each cameras uses its own algorithm to try to determine which part of the scene it should focus on but there is no way for it to get it right every time. That's why cameras allow you to manually choose focus point as well and that's what you need to do when the camera is focusing somewhere other than what you want.

PDAF has traditionally been faster than CDAF. However the panasonic and olympus mirrorless cameras have very fast CDAF systems which are as fast as high-end PDAF based DSLRs for single-shot AF. Of course AF speed depends a lot on the lens as well for both CDAF and PDAF. CDAF is also generally more accurate and does not suffer from the front-focus or back-focus issues that can occur in PDAF based systems due to imprecise calibration.

The major advantage that PDAF still holds is in tracking and video AF. We don't know yet how these upcoming NEX cameras will use PDAF but it is not likely that PDAF will replace CDAF on NEX. It will most likely work in some hybrid fashion to aid the CDAF. Depending on how they use PDAF, it maybe that the primary advantage is only in video / tracking, though it can help improve single shot AF as well.

harry2007 wrote:

Hi all,

Sorry if this is quite a basic question.

I read all the rumors of the new PDAF (Phase Detection AF) on the upcoming new NEX-5R and NEX-6.

Is PDAF any better than CDAF?

I read that it is "faster", so the auto-focus will be much faster.

And I agree if this is one of the advantage, because my NEX-5 auto-focus is a bit slow.

But, will this help to improve out-of-focus (OOF) that users often get using NEX?

Because I also read quite a lot that issue and experienced myself.

The NEX will focus on the background, instead of the subject.


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