G3 heralds the end of APS-C DSLRs

Started May 13, 2011 | Discussions thread
Anders W Forum Pro • Posts: 21,468
Re: and that's before we talk AF micro-adjust! ;-)

ljfinger wrote:

Anders W wrote:

ljfinger wrote:

Evidence abounds. Plenty even in these forums from experts.

I still don't see any evidence. Just a claim that it exists.

CDAF works by guessing, moving, stopping and then determining whether or not the guess was right, and then either moving some more in the same direction if the guess was right or in the reverse direction if the guess was wrong.

No, it doesn't work like that. The motor runs continuously.

Single-area AF-S:
G2: 0.423 second
GH2 (2010): 0.273 second.

These numbers are meaningless. First of all they are largely dependent on the distance they had to go and the speed of the focusing motor.

Same distance, same lens.

Second, they are for static subjects for which focusing speed is irrelevant.

Of course, it's not irrelevant because "static subjects" are often less than perfectly static.

Third, most compacts can achieve similar numbers. They're all dirt-slow.

What compacts go equal with the GH2. And which DSLRs are faster?

Focusing speed is important for tracking moving subjects, not for achieving initial focus.

See above.

Reports on the forums are not a good overall cross section.

Why not?

The fact that these cameras have sold in the tens of millions over the years indicates that they are staying sold, which they wouldn't if they didn't work. So they do work.

It just indicates that until now there has been nothing better.

Fortunately, it's not a big issue, and they miss far less frequently than CDAF cameras do when faced with challenging conditions.

Depends on which CDAF system you compare with which PDAF system. Which comparison do you have in mind and what publicly available evidence do you have to back it up (and don't show me any more sample images of yours; that's illustrations, not evidence).

Yes, CDAF is more accurate theoretically in simple static conditions.

And in practice too.

For those that shoot in those conditions a lot, it should be satisfactory.

My PDAF system is not satisfactory to me for the conditions we are talking about.

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