Help me understand if pdaf works or not

Started Jan 30, 2013 | Discussions thread
blue_skies
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Re: Help me understand if pdaf works or not
In reply to Adi Wibowo, Jan 30, 2013

Adi Wibowo wrote:

Photozopia wrote:

We know all this ... in theory anyway ... so why does PDAF display remain over f6.3 if inoperative?

I try again by setting the lens (55-210) to f22 and then look into the lens from the front. The aperture was fully opened (I set Live View Display as Setting Effect OFF so changes at aperture only happen when shutter button pressed). When I half pressed shutter button, there was delay about half a second before the aperture closed to f22. When I looked back to lcd and try again, yes there was similar process, the camera try to achieve focus while the lcd is still bright, and then gone dark when the aperture set to f22.

So I know that the focusing process happened while the aperture was fully opened. The aperture then closed down to desired number after focus achieved. The only thing I don't know is whether it is CDAF or PDAF because pdaf display is there all the time.

It is confusing. Or may be we just thinking too much and don't have to worry whether it is pdaf or cdaf that is being used by the camera? That's why sony still display pdaf grid whether it is working or not.

Maybe not confusing, but interesting - if live view is OFF, the camera then uses the full aperture of the lens, so it is essentially PDAF focusing wide open. If live view is ON, the camera uses the actual selected aperture, as the lens is already stopped down, and then it falls in the PDAF/CDAF division at around f/6.3. Given the large DOF at small apertures, this may just be fine.

You can turn of the PDAF grid, but it doesn't turn of the PDAF focusing method, to my understanding.

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Cheers,
Henry

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