Performance of a9 focusing stopped down in AF-C in low light?

Started 3 months ago | Discussions thread
vett93 Veteran Member • Posts: 4,867
Re: Performance of a9 focusing stopped down in AF-C in low light?

lattesweden wrote:

Sony AF is great in all regards but this.

Stopped down focus in low light is simply not Sonys strength.

And the various ways of trying to fix this have still not produced a proper solution. The A7RIV is the closest so far, but seems still to be lens dependent. My last check was at the end of the summer, so any changes from that I might have missed. With many lenses the situation then was that it didn't work with forcing wide open focus with stopped down working aperture.

On the A9 it is only a few lenses that works with Aperture Drive in AF and Focus Priority and only with e-shutter as you pointed out so no use for us low light club event shooters that want to use flash.

So apart from doing what most articles and videos suggest: turn off the live view effects etc, I have found that AF-S works best (same also goes for A7RII and A7III and probably other bodys). AF-S is slower but nails the focus in low light with stopped down working apertures. And the DOF at f5.6 or 8 is enough for some movement of yourself or the subjects between AF-acquisition and image capture.


In these conditions, AF-S would AF at the wider aperture, not the working aperture. Jim K. did the test and reported it some time ago.

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