a6000 Prime Lenses

Started Aug 16, 2014 | Discussions thread
audiobomber Veteran Member • Posts: 5,764
Re: Yes, the Sigma Lenses have PDAF in the center

tomtom50 wrote:

audiobomber wrote:

Pepe-Lepue wrote:

audiobomber wrote:

Pepe-Lepue wrote:

tomtom50 wrote:

PDAF does work with the Sigmas, but only in the center.

I don't believe it does. My 30mm Touit does not support PDAF, yet in AF-C mode with Wide focus area, I get flashing green squares in the Center AF area. Clearly this does not show that PDAF is available, because everyone agrees the Touit does not use PDAF. From your description, the Sigma acts the same way.

My Touits work with PDAF in center. In AFC wide I get the tiny squares in the center indicating PDAF.

You should tell Zeiss about this, because they say that PDAF will only be available after a FW update. Seriously though, what makes you think that the green points lighting up in AF-C mode are PDAF points, and not CDAF points? Common sense says they are CDAF points, like you would see on a camera without PDAF.

Here's a page from the A6000 documentation explaining PDAF.

Interesting. This proves that the Sigmas and Touits do not have PDAF, because they cannot access the Wide or Zone focal points in AF-C.

I don't know about the Touit. I don't have one.

PDAF is more than flashing little squares (which the Sigma has in the center)

It is how the camera behaves. CDAF shows itself by "shimmering" as the camera passes back and forth over best focus. It shows itself by shimmering every time you acquire focus.

PDAF doesn't jiggle focus the same way. PDAF, if you are in focus, instantly turns green again if you acquire focus without any shimmering.

CDAF, if you are in AF-C, pumps focus like a maniac and cannot track focus well. PDAF does not pump focus and track focus nicely.

So the little green squares are an obvious thing to note, but the camera simply behaves differently in PDAF vs. CDAF. And the Sigma has PDAF behavior in the center and CDAF elsewhere.

You reached a conclusion about what Sigma does or doesn't do based on press releases from another brand. Not so dispositive.

BTW, the Sony 16mm truly cannot do PDAF at all, even in the center.

OK Tom, you have convinced me. The a6000 manual says PDAF is not available at f13 and smaller. I tested with the Touit and 16-50 and they behaved similarly, no green squares after f13.

I will never again say that the Sigma DN lenses do not allow PDAF. They do, in the center only, as do the Touits. From now on when trying to distinguish features between these lenses and lenses with full PDAF capability, I will say that they allow PDAF but only in the center, thus do not allow subject tracking.

-- hide signature --


 audiobomber's gear list:audiobomber's gear list
Pentax K-3 Sony a6000 Pentax K20D Pentax smc DA 15mm F4 ED AL Limited Pentax smc FA 50mm F1.4 +19 more
Post (hide subjects) Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow