Sony a6400 Autofocus Settings: A Beginner's Guide

For most subjects, set your Sony a6400 to continuous autofocus with the Wide focus area, then let Real-time Eye AF and Real-time Tracking take over when you half-press the shutter. Switch to Flexible Spot when you need to decide exactly what is sharp, and move that point with the touchscreen.

Below you'll find what each setting does, where to find it, and a simple starting setup you can change as you learn.

How the a6400 autofocus system works

The a6400 uses a hybrid AF system with 425 phase-detection points and 425 contrast-detection points. Sony says those points are spread densely over approximately 84% of the image area. The system inherits technology from Sony's full-frame a9, a7R III and a7 III models.

Sony claims the a6400 can acquire focus in 0.02 seconds. Fstoppers points out that Sony reached that figure with the 18-135mm kit lens mounted. Digital Camera World lists the system as sensitive down to -2EV, so it can still focus in fairly dim light.

Autofocus spec	Sony a6400
Phase-detection points	425
Contrast-detection points	425
Frame coverage	About 84%
Claimed focus acquisition	0.02 seconds
Low-light focus limit	-2EV
Burst with AF/AE tracking	11fps mechanical, 8fps silent

All of this is set through menus, buttons and the screen. Digital Camera World's review notes that the camera's features are accessed electronically via menus, screens, dials and function buttons rather than dedicated knobs. Spend ten minutes learning the two controls below and you'll reach most autofocus settings quickly.

Focus modes: when the camera focuses

A focus mode decides whether the camera locks focus once or keeps adjusting it. Sony's announcement names AF-C and AF-A among the a6400's autofocus modes. Neocamera's spec sheet notes that autofocus can continuously adjust according to subject distance, and that manual focus is also available.

The a6400 has a dedicated button for swapping AF modes. Use it whenever your subject changes from still to moving.

Which focus mode to start with

If you're new to the camera, start in AF-C. Continuous focus keeps following your subject while you hold the shutter halfway, which suits kids, pets, people walking and anything else that won't stay put. It also gives you the most Eye AF options, because choosing a preferred eye only works in AF-C or AF-A.

Eye AF itself works in both single-shot and continuous shooting. So if you prefer a mode that locks focus once for still subjects like landscapes or products, you won't lose eye detection for portraits.

When to use manual focus

Manual focus is a fallback for scenes autofocus can't read. In Fstoppers' first-impressions review, the writer tried to photograph a brown bird moving through equally tall brown foliage, and autofocus couldn't pick it out. That writer switched to manual focus and still missed, and felt the viewfinder pixels were too big and the focus assist zoom too low quality to judge focus accurately. The lesson for you: manual focus on this camera is workable, but magnify the view and take several frames when it matters.

Focus areas: where the camera focuses

A focus area tells the camera which part of the frame to look at. Imaging Resource lists these options for the a6400: Wide, Zone, Center, Flexible Spot (S/M/L), Expanded Flexible Spot, and Tracking versions of each of them. You change the focus area through the Fn button on the back.

Wide

Wide is usually the default, and it automatically selects the focus area based on the subject. It's the easiest place to start, especially with Eye AF doing the work on people. The trade-off is control: in a busy scene the camera may choose something other than what you wanted.

Flexible Spot

Flexible Spot lets you choose the focus point yourself. It comes in small, medium and large sizes. Use small for precise targets like a single flower in a group, and medium or large when your hand or the subject is moving a little.

Moving the point is where the touchscreen helps. Photography Blog notes that touch makes focus point selection much easier, especially given the lack of a rear AF joystick, and that it works while you're looking through the electronic viewfinder. The same review points out that you can't use the touchscreen to navigate the main menu or quick menu. Expect to use it for focus, not for settings.

Zone, Center and Expanded Flexible Spot

These three sit between Wide and Flexible Spot in the list. Once you're comfortable with Wide and Flexible Spot, try each one on a subject you photograph often and keep whichever gives you the fewest missed frames.

Real-time Eye AF

Eye AF finds a person's eye and focuses on it. Real-time Eye AF is the version Sony introduced on the a6400, using AI-based object recognition to detect and track eyes.

The big change for beginners is how you switch it on. Photography Blog explains that it's instigated by half-pressing the shutter button, rather than via a custom button as on previous models. Sony says that in all autofocus modes the camera automatically detects eyes and activates Eye AF with a half-press.

Choosing which eye

In AF-C or AF-A, you can choose the preferred eye: Auto, Right Eye or Left Eye. Sony also lets you assign a Switch Right/Left Eye function to a custom button. Leave it on Auto at first. If you shoot a lot of three-quarter portraits, assign the switch to a button so you can flip to the nearer eye without opening a menu.

How well it works

In Digital Camera World's review, the face and eye detection followed faces around the frame with no lag at all. In continuous AF and continuous shooting, the reviewer found that the autofocus responded to changes in subject distance practically instantly.

Animals

Sony announced that eye tracking for animals would be added in a camera update in summer 2019. Results are more limited than with people. A Digital Camera World writer found the subject detection works on animals but had to zoom in pretty close for it to kick in, and often had to supplement it by moving the focus point manually. For pets and wildlife, fill more of the frame with the animal and keep Flexible Spot ready as a backup.

Real-time Tracking

Real-time Tracking follows a subject you pick as it moves around the frame. Sony describes it as an object tracking function that "keeps the most challenging moving subject in focus".

Where to find it

Fstoppers explains that Real-time Tracking replaces what was previously labeled Lock-on AF in the focus area menu. It isn't a focus area by itself: inside the Tracking setting, you tap left or right to choose which area it starts from, such as Zone, Wide or Flexible Spot. You can also start it by tapping your subject on the screen.

A practical choice is Tracking with Flexible Spot. You place the small box on your subject, half-press, and the camera follows it from there.

What the camera is looking at

Digital Camera World describes the system as AI-based object recognition that processes colour, subject distance and patterns as spatial information. Fstoppers breaks it into three layers: colour, pattern and distance on the outside, then a face if it finds one, then the eye on that face. If something passes in front of the eye, the camera holds the face, and if the face turns away, it falls back on the colour, pattern and distance it learned.

That explains a common beginner surprise. If your subject turns their back, the box doesn't vanish; the camera keeps following the shape and colour it remembers.

Limits to know

Digital Camera World found Real-time Tracking a bit more sluggish than face detection: it lost fast-moving subjects and needed a couple of frames to find them again, but only when deliberately provoked. The same review says it handled relatively slow-moving subjects fine. Sony also told Fstoppers that tracking performance depends on the camera and lens combination. For fast action, shoot short bursts rather than single frames so a lost frame or two doesn't cost you the moment.

Autofocus for video

The same tools carry over to video. Fstoppers notes touch to focus in video mode, and Real-time Tracking started by tapping the subject. For its sample footage, Fstoppers generally used Wide AF or Tracking AF. The camera can also record Full HD at 120fps with AF tracking for slow motion.

For talking-head clips, Wide with Eye AF is a simple setup. For a subject walking through a scene, tap it on the screen to start tracking. Digital Camera World points to the 180-degree screen and eye-detect AF as handy for single-handed video capture.

Starting settings to try

These are starting points, not rules. Change one setting at a time and look at your results.

What you're shooting	Focus mode	Focus area	Extra
Portraits, family, friends	AF-C	Wide	Eye AF on Auto
Kids, pets, people moving	AF-C	Tracking with Flexible Spot	Short bursts
Landscapes, still objects	Single-shot focus	Flexible Spot (small or medium)	Move the point by touch
Vlogging, talking to camera	Continuous	Wide	Eye AF, screen flipped up
Busy scenes where AF picks the wrong thing	AF-C	Flexible Spot	Manual focus as a last resort

If you're also setting up exposure and buttons, the Sony Camera Menu Setup Guide walks through the menu layout, and Camera Specs Explained covers what autofocus numbers mean.

Where the a6400 autofocus falls short

The a6400 was introduced in 2019, and the newer a6700 adds an AI chip for smarter, faster autofocus. Digital Camera World reports that the A6700 locked focus and followed a fox in near darkness in its tests, and credits the AI chip working alongside the Bionz XR processor. The same writer said that for wildlife they wouldn't hesitate to pay more for the A6700 over the A6400.

For people, everyday moving subjects and video, the a6400's autofocus still earns praise. Photography Blog called its real-time tracking something of a game-changer for portrait and action photography. If you're weighing an upgrade, the Sony A6700 Autofocus Guide explains that camera's system, and Sony A6400: Still the Best APS-C Camera for Learning Photography? covers the wider comparison.

Body only or kit

You can buy the a6400 body only or with the compact 16-50mm power zoom. The kit is the simpler way to start if you don't own E-mount lenses yet. The body alone makes sense if you already have lenses or want to choose your own.