A57 focus point size?

Started Nov 12, 2012 | Discussions thread
philbot Contributing Member • Posts: 846
Re: A57 focus point size?

wik2kassa wrote:

Since the a57 is capable of doing CDAF and PDAF simultaniously. is there an option to select CDAF only? Thus changing the size of the AF area.

The A57 only does PDAF (as all SLT models)..

And as with all PDAF systems, you can only select 'areas' which combine individual PDAF sensors ('Zone' or 'Wide' AF Modes)..

The problem with CDAF on DSLRs is more the lenses, the mechanics and design are suited to PDAF, when used with CDAF they are very slow (hence why other DSLR CDAF Liveview modes have such slow AF, SLT was different in allowing PDAF in liveview for super fast AF with normal lenses). Only canon have started doing some 'STM' lenses that work with their Hybrid PDAF/CDAF AF mode on the T4i/650D..

PDAF/CDAF have their own limitations, but at the end of the day, PDAF is seen as more suited to DSLRs at the moment, and you have the Spot/Zone/Wide AF modes to accomodate different AF area sizes, giving some flexibility.

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