The Sony a6400 allows for a microphone input and HDMI output. But there's no headphone port, and you cannot output 10-bit video over HDMI.

The Sony a6400 shoots nicely detailed 4K video, has a full suite of capture aids and a flip-up screen intended to make vlogging easier. Apart from the screen, it's largely the same feature set from Sony's previous a6300: but the market hasn't stood still, and though the a6400 is a capable video camera, it has some shortcomings that you may not need to deal with on contemporary competitors.

Key takeaways:

  • 4K video is highly detailed, being downsampled from higher-resolution capture
  • No crop in 4K/24 or 25p, 1.2x crop in 4K/30p
  • Pronounced rolling shutter artifacts, especially shooting 4K/24p/25p
  • No in-body image stabilization
  • Camera does not retain separate exposure settings for photo and video
  • Focus peaking, zebra warnings, flat Log profiles (though limited to 8-bit capture)
  • Tap-to-track autofocus works well, but you may want to disable it for shooting stills
  • Microphone socket allows for easy high-quality audio, but no headphone option

In depth

When Sony first introduced the a6300, we were pretty excited about the possibilities of its oversampled 4K video. It also offered an incredibly complete feature set to aid capture, including focus peaking, zebra warnings, a variety of Log profiles, solid phase-detect autofocus and a microphone input. We weren't all that sold on its middling 1080p video capture, but hey, you can always shoot 4K and downsample yourself.

Sony has removed the limit on record time
on the a6400

And now, three years later, the a6400 takes all that and adds a touchscreen that flips up 180 degrees for vlogging (and selfies), as well as 'tap-to-track' capability in video. Those are important usability changes, to be sure, but the a6400 isn't the only game in town any more. Plus, the utility of the upward-tilting screen is questionable if you were hoping to use a hotshoe-mounted microphone, which would block most if not all of the screen.

On the other hand, Sony has removed the limit on record time, which makes the a6400 a compelling option as a B-cam for long interviews and the like. The updated processor looks to have done some good for heat issues as well; we've recorded multiple 45+ minute clips indoors at standard room temperature 20°C (68°F) with no issues. Your mileage may vary, particularly if you're shooting in hot weather or in sunny conditions, but this is a nice change from previous Sony models that were especially prone to overheating.

Video options

The following are the options for the a6400 while the camera is in NTSC mode. Switching to PAL replaces 120/60/30 options with 100/50/25 respectively (24p is not available in PAL mode).

The camera also offers Proxy Recording, which records a second lower-quality movie in parallel with your main clip, if you're shooting at 30p or lower frame rates. These proxy movies can be used to lighten the editing load and can also be transferred over Wi-Fi much more quickly than the full-size files.

Format Resolution Frame Rate Bitrate (mbps)
  • 3840 x 2160
  • 30p*
  • 24p
  • 100/60
  • 100/60
  • 1920 x 1080
  • 60p
  • 30p
  • 24p
  • 120p*
  • 50
  • 50
  • 50
  • 100/60
  • 1920 x 1080
  • 60i
  • 24/17

* Taken from a cropped region of the sensor (4K/25p is not)

Here's a look at how the a6400's footage is cropped (it's identical to the a6300), depending on which mode you're shooting in:

• 4Kp/25/24
• 1080p/60/50/30/25/24
• 1080p/120/100 • 4Kp/30

Video tools and handling

As mentioned earlier, the a6400 has an impressively comprehensive suite of capture tools to aid you in shooting video. Focus peaking and focus punch-in both work well for manual focus shooters, and work while recording. For exposure, you get a a histogram and zebra stripes if you like, and you can also use the audio meters to monitor your audio and the on-screen level to keep your horizons straight.

This option lets you choose whether you want to use the touchscreen to move your AF area around by tapping or dragging on the screen, or have a tap on the screen initiate tracking on that chosen subject.

Sony has also now enabled an easy 'tap-to-track' implementation in video shooting that many competitors have had for some time. This is accomplished by changing 'Touch Focus' to 'Touch Tracking' in the menu shown above (it should really be in the AF menu pages). The downside to this tap-to-track implementation is that whether in video or stills, you cannot now use the touchscreen to move your AF point (touchpad AF when using the viewfinder is disabled as well).

We'd love to see Sony make this an option that 'remembers' which mode you're in; I found touch tracking really useful in video, and though some users may find they like it for stills shooting, I preferred being able to use the screen to move my AF area around independently of initiating tracking. This also carries over into exposure settings; switch the a6400 from stills to video, and it will retain those exposure settings, even though users will very rarely want them to actually be the same between those two mediums (you'll often want much slower shutter speeds for shooting video than for stills).

I found touch tracking really useful in video, less so for stills shooting

For vlogging, you can pretty much leave the a6400 in the 'Wide' AF area (non-tracking) with face detection enabled, and it should follow and focus on your face quite well. When paired with a wide-angle lens like the 10-18mm F4 OSS, the camera is light enough to comfortably hold out in front of you, and the wide-angle lens means you don't need to extend your arm all the way to get some decent framing. You'll probably want to use a lav microphone, since a hotshoe-mounted mic would block the screen (or get yourself one of these).

‘Demonstration of ‘Touch Tracking’ video autofocus. Tap on your subject and the camera will continue to track and focus on it. Tap another subject to switch to it. In this video, I switch repeatedly between the toddler, her mother, and the first lock of hair she had cut.

Sony 24/1.8 | 4K/30p (1.2x crop) | Effective focal length after crop & warp stabilize: 52mm

Lastly, for advanced shooters, the a6400 comes with Sony's Log profiles, which capture very 'flat' low contrast footage to allow for more flexibility in post-processing. Unfortunately, unlike many competitors that now have the same Log capability, the a6400 cannot capture or output 10-bit footage to an external recorder. This means that you risk posterization or 'banding' if you push the Log footage too far, whereas 10-bit footage captures much more information and therefore the files respond better to editing and grading with fewer artifacts.

For more information, we dive into the nitty-gritty of Log footage in our Panasonic GH5S review here.

Detail capture

Regarding video, the a6400's most natural competitor at the time of this writing is Fujifilm's X-T30. As you can see, they both offer very detailed 4K video capture across the scene. The a6400 also holds up well in comparison to Sony's much pricier full-frame a7 III.

It's worth noting that our scene here doesn't tell you much about rolling shutter, but for comparison's sake, the a6400 has a shutter scan rate of 40ms when shooting 4K/24p and 31ms when shooting 4K/30p. The X-T30 has a scan rate of 23ms, which is much better and really tamps down on the jello effect or slanted verticals that rolling shutter can result in.

For those that don't want, need, or have the ability to edit 4K footage, 1080p output from the a6400 is a bit disappointing. We've been seeing this from Sony for some time now, with less-than-stellar footage compared to many competitors, even those with 1080p footage what we weren't super impressed by.

Jordan's video review

Our Canadian compadres have taken a close look at the a6400 as well, with Jordan Drake breaking down his take on the camera's video capabilities.