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Sony A7 Phase Detection system


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Having owned my A7 for several months and having read numerous sources , is my understanding of this system correct ? .....

 

1. It only works at F9 or smaller apertures

 

2. It works with  continuous AF NOT single AF

 

3. It requires a compatible lens and even some compatible lenses require appropriate firmware updates

 

4. It only works AFTER contrast detection has established an approximate range.

 

 

So apart from tracking focus in bright light what good is it ?

 

FWIW I'm quite happy with the AF as it is but I suspect Sony oversold the Phase Detection bit.

 

 

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I think you have points 1 and 4 wrong. Point 2 is correct and probably also point 3.

 

Works great for me, no complaints other that the whole AF setup is rather confusing. I would welcome the option to *remove* the various modes that I never use simply to unclutter the menus.

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I've used it in Bright snow and a Dim sports arena. It worked fine. Like you I wondered why it was only available in some cases, C-AF and Tracking, but actually after using it I guess Sony only made it available where it makes sense - moving subjects, where it really helps. Fair enough.

 

F9 and smaller apertures ... should that be F9 (or whatever) and larger apertures

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I've used it in Bright snow and a Dim sports arena. It worked fine. Like you I wondered why it was only available in some cases, C-AF and Tracking, but actually after using it I guess Sony only made it available where it makes sense - moving subjects, where it really helps. Fair enough.

 

F9 and smaller apertures ... should that be F9 (or whatever) and larger apertures

 

I'm old school ( 1960s ) where a smaller hole meant smaller apertures ( not sure when that changed ..perhaps it was a US definition now used more widely ) ! 

I mean F9 towards F22

 

My Fuji X100S uses a similar Sony-made on-chip PDAF system but without published limitations.

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It works from Maximum Aperture (in my case F4) down to around F11 or so. Not sure if the Aperture limit is fixed in the camera or on a per lens basis. If its quite dark the camera switches to contrast detect. I got the impression for shooting in Sport Scene that Autofocus now depends on a number of techniques and strategies, selecting the right one for the task does help ... or using the Scene Modes, which feels wrong, but actually works quite well.

 

From the limited reading I have done, the Fuji cameras have the same limitations.

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