Why do reviews criticize the AF on the A7?

Started Dec 26, 2013 | Discussions thread
GXRuser Contributing Member • Posts: 656
Re: Why do reviews criticize the AF on the A7?

photo perzon wrote:

Will Sony fix it?

Which reviews?

AF criticism always come in context of.

The A7 has PDAF, but some reviewers were new to the camera and used it incorrectly at the time. They reported many OOF shots.

If you consider high end PDAF cameras (such as FF DLSR), focusing is blindingly fast and accurate. The A7 does not meet this level of performance, in fact, even the LA-EA2 does not meet this either.

If you consider fast CDAF cameras, e.g. the Nikon 1, focusing is helped a lot by the increased DOF of the smaller sensor, and Nikon implemented a clever algorithm. You get a lot of keepers with this system (but you are ISO limited due to the smaller sensor).

For large sensor (mirrorless) CDAF cameras, the A7 has a reasonably acceptable speed and accuracy. Sony already did a great job in improving it. Sure, we still want more, but not at the compromise of image IQ (e.g. all cells become PDAF cells).

And then, moving subjects, that approach you, like dogs and children, do not allow for a 'shutter-half-press, confirm-AF, reframe-and-shoot' method. You have to press the shutter all at once. Sony's PDAF mirrorless cameras do have a reasonable performance for such shots, but the CDAF cameras will miss these shots. Of course, the maximum approach speed depends on FL and aperture - there is a limit that is easily exceeded.

Rather than criticizing, the reviewers should explain when it works, and when it fails. DPreview did so in the Nex-6 review, and they commented positively in the A7 preview (addendum - they retracted their earlier finding).

I find the A7 to be a minor improvement on the Nex-6. It is a tad faster, and a tad more accurate. I am more comfortable to press the shutter all at once on the A7 than I was on any Nex camera. Yet, if the scene does not require it, I tend to avoid it - heck even use DMF, for it is so easy to confirm focus.

So back to you, Sony will fix what is broken. So what exactly is broken?

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one correction of a great post....

Nikon 1 cameras have on sensor PDAF.

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