Sony A6400 Performance

Improved AF speeds and buffer depths compared to the A6300, though buffer clearing is still slow.

The Sony A6400's startup time (power on to first shot) of 1.8 seconds was a bit slower than average for a mirrorless, and oddly tested slower than the A6300's 1.4 seconds in our tests. Switching from Play to Record mode and taking a shot was also slightly slower at 1.0 versus 0.7 second.

The Sony A6400's full-autofocus shutter lag (with the subject at a fixed distance) was very fast, measuring only 0.115 second in Single-area (Center) AF mode with the FE 35mm f/2.8 lens. That's a significant improvement over the A6300's already fast 0.160 second.

Enabling the flash added a slight delay for preflash metering, increasing lag to about 0.171 second, but that's much improved over the 0.437 second we measured for the A6300.

When manually focused, the Sony A6400's shutter lag was 0.111 second, just slightly slower than the A6300's 0.107 second. The A6400's prefocused shutter lag was incredibly fast at only 0.021 second, very similar to the A6300's 0.020 second result.

Note that our tests were performned using the default Electronic First Curtain Shutter (EFCS) mode. Mechanical and electronic shutter modes were slower but still pretty fast.

To minimize the effect of different lens' focusing speed, we test AF-active shutter lag with the lens already set to the correct focal distance.

Single-shot cycle times were very good, at about 0.4 second for Large/Extra Fine JPEGs and RAW + Large/Extra Fine JPEG frames, a little faster than the A6300. (Note that we no longer test single-shot mode with just RAW files, as the results are usually somewhere in between JPEG and RAW+JPEG modes.)

The Sony A6400's fastest Continuous Hi+ mode was very fast at about 11 frames per second no matter the file type, and very closely matching the A6300's top speed. Note that continuous AF is supported in this mode, but unlike the A6400's other continuous modes, Hi+ mode displays the previously captured image which can make tracking a moving object difficult during a burst.

Continuous Hi burst mode performance also closely mirrored the A6300 at just over 8 frames per second There are also Continuous Mid (6 fps) and Continuous Lo (3 fps) settings, however we did not test those options in the lab. With these modes, tracking a moving subject is easier than Hi+ mode since the real-time preview is updated between captured frames.

Buffer depths were almost double what the A6300 managed. When shooting best quality JPEGs, buffer depth ranged from 87 frames in Hi+ mode to 98 frames in Hi mode, compared to 44 and 46 for the A6300. Of course, when shooting RAW or RAW+JPEG files, buffer depths are lower at 42 frames for RAW or RAW+LEF JPEGs, compared to between 21 and 24 frames for the A6300 depending on the file type. Also be aware that the A6400 can shoot Extra Fine JPEGs along with RAW files, while the A6300 dropped JPEG quality down to Fine when shooting RAW+JPEG pairs.

Buffer clearing after max-length bursts was quite slow with a fast card (the A6400 is UHS-I compliant, but our Lexar Pro UHS-II SDXC card's UHS-I mode is fast), ranging between 26 seconds after a max-length burst of RAW files, to 56 seconds after a max-length burst of Large / Extra Fine JPEGs. This is even slower than the A6300, but that's because the buffer is much deeper. Unlike the A6300, though, the A6400 lets you adjust settings or view just-shot photos while the buffer is clearing, however it's still a shame Sony didn't add faster UHS-II support.

The built-in flash was able to recycle from a full discharge in 2.3 seconds, which is good.

Bottom line, the Sony A6400's performance is generally excellent for its class, with improved autofocus speed and almost double the buffer depth compared to the A6300, but buffer clearing is still very slow after long bursts. At least the A6400's UI doesn't freeze up while the buffer is clearing, though.

Battery Life
Good battery life for a mirrorless camera.

The Sony A6400 uses a custom NP-FW50 rechargeable lithium-ion battery pack for power and ships with a single battery, AC/USB adapter, and a Micro USB cable for in-camera charging. A dedicated battery charger is optional. While CIPA-rated battery life is good for a mirrorless camera, it's well below most DSLRs, especially when using the electronic viewfinder. We strongly recommend purchasing an additional battery or two for extended outings.

The table above shows the number of shots the camera is capable of (on a fully-charged rechargeable battery), based on CIPA battery-life and/or manufacturer standard test conditions.

(Interested readers can find an English translation of the CIPA DC-002 standards document here. (180K PDF document))