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

Started 3 months ago | Discussions thread
lattesweden
lattesweden Veteran Member • Posts: 3,194
Re: Performance of a9 focusing stopped down in AF-C in low light?
2

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.

Use the Reg Cust Shoot Set function that actually can include change of AF-mode to AF-S even if the focus wheel stands in AF-C on the A9. As well as also include your aperture setting etc. Makes it quite easy to switch to group portrait settings with just a custom button press and hold:
https://helpguide.sony.net/ilc/1650/v1/en/contents/TP0001491336.html?search=custom%20hold

Now, if you for some reason really need AF-C in low light with stopped down apertures then the AF-S "trick" is obviously of no use.

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Best regards
/Anders
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