Sony cameras have had fantastic video autofocus for years, but here’s the part that surprises a lot of people: out of the box, your FX3 or A7S III is not using the best autofocus settings for video.
The good news is that there are only two major issues holding Sony’s video autofocus back, and both of them are easy to fix once you know where to look. After making these changes, your autofocus will be more accurate, less jumpy, and most importantly, feel far more natural and cinematic.
If you want to save time, I’ve also created a free autofocus cheat sheet for Sony cameras that shows all of my recommended settings at a glance.
And if you really want to unlock everything these cameras are capable of, I also offer full FX3 and A7S III Pro Video Guides that walk through every menu item, include downloadable camera presets, and even color presets that work in any editing software.
Now let’s talk autofocus!
Why Sony Video Autofocus Isn’t Perfect Out of the Box
Straight out of the box, autofocus on the FX3 and A7S III is fast and accurate. Face and eye detection works well, and tracking is impressive.
But there are two big problems once you actually start filming real-world scenarios.
First, autofocus is not sticky enough.
Second, autofocus transitions are too fast and feel very digital.
Let’s fix both.
Problem #1: Autofocus Isn’t Sticky Enough
Have you ever been filming someone, everything looks great, and then another person walks into frame and suddenly the camera jumps focus? Or maybe your subject turns their head slightly and the focus shifts to something else in the background.
That happens because, by default, Sony wants the autofocus to be extremely responsive. The camera is constantly scanning the frame, asking itself if it should focus on something new.
That can make autofocus feel impressive at first, but in practice, it makes it unreliable.
The Setting That Fixes It: Subject Shift Sensitivity
Grab your FX3 or A7S III and make sure you’re in video mode.
Press the menu button and go to the purple AF/MF menu.
Set your focus mode to Continuous AF.
Then scroll down to AF Subject Shift Sensitivity.
This setting controls how easily the camera will abandon your current subject and jump to something else.
At level 5, which is the default, the camera is very responsive. It will happily jump between people and objects as they enter the frame.
At level 1, the camera is extremely locked on and will resist changing focus almost entirely.
After a lot of testing, I’ve found that level 3 is the sweet spot.
At level 3, autofocus stays locked on your subject far more reliably than the default setting, but it still has enough flexibility to shift focus when you actually want it to. If your subject exits the frame, the camera won’t fight you forever.
This single change dramatically improves autofocus reliability.
Problem #2: Autofocus Feels Too Fast and Robotic
The second issue is more subtle, but just as important.
Out of the box, autofocus transitions on these cameras are extremely fast. When your subject moves forward or backward, the camera snaps into focus almost instantly.
Technically, that sounds like a good thing. Visually, it often isn’t.
Fast autofocus transitions can feel jarring because they don’t look human. Background blur shifts instantly, and it can pull viewers out of the moment without them even realizing why.
There’s a reason most high-end cinema productions still use manual focus with a dedicated focus puller. Human focus changes take a moment, and that delay feels natural to us.
Your eyes work the same way. Focus on something close to you, then look at something far away. There’s a brief transition. That’s what feels normal.
Sony’s default autofocus speed skips that entirely.
The Setting That Fixes It: AF Transition Speed
Go back into the autofocus menu and select AF Transition Speed.
This setting controls how quickly autofocus moves from one focus distance to another.
A value of 1 is very slow.
A value of 7 is extremely fast.
The default is 5.
For video, 5 is too fast.
I recommend setting this to 4. It still feels quick and responsive, but the transitions are smoother and more natural. If you want an even more cinematic feel, you can experiment with 3, but for me, 4 is the perfect balance.
All of my Sony cameras are set this way.
What These Settings Do for Your Footage
Once you adjust subject shift sensitivity and autofocus transition speed, you’ve fixed the two biggest autofocus issues on the FX3 and A7S III.
Autofocus becomes more reliable.
It stays locked on your subject.
Transitions feel smoother and more human.
Instead of feeling like a robot snapping focus in milliseconds, it feels like a skilled focus puller gently guiding your viewer’s eye.
A Note on Presets and Advanced Autofocus Control
If you don’t want to dial these settings in manually, my FX3 and A7S III Pro Video Guides include camera preset files that install directly onto your camera with all of this already configured.
The guides also go deeper into things like touch tracking, custom buttons for toggling autofocus, and how to adapt autofocus behavior for different shooting scenarios.
They’re designed to save you time and help you get the absolute best results from your camera.
Final Thoughts
Sony’s video autofocus is already excellent, but with a couple of simple setting changes, it becomes dramatically better!
If you want to go even further, be sure to download the free autofocus cheat sheet for all Sony Cameras, and check out the full Pro Video Guides when you’re ready to master every setting.
Thanks so much for reading, and have a great day.