Buzz
Sensor
The first notable difference lies in the sensor format. A7 III utilizes a full-frame 35mm BSI sensor whereas a6400 features a smaller APS-C chip.
These two Sony cameras share a common ground in providing 24.2MP resolution, capable of recording in 14-bit RAW compression, and both are equipped with the latest Bionz X image processor. However, there's a difference in ISO. While A6400 has a basic ISO range of 100-32000, extendable up to 102400, A7 III boasts a basic ISO range of 100 – 51200, extendable up to a whopping 204800.
Image Stabilization
Sony Alpha A7 III boasts image stabilization rated at 5Ev according to CIPA standards for both stills and video. Meanwhile, A6400 lacks built-in stabilization, so the only option for stabilizing images is to use optically stabilized lenses or third-party support like traditional camera tripods or gimbals for video.
Design
In terms of design, A6400 is noticeably more compact compared to A7 III. This is because Sony A6400 integrates fewer physical control buttons; the camera has only one custom button on top, no exposure compensation button, and no AF control button. Another important point is that A7 III has two memory card slots, whereas a6400 has only one and supports only UHS-I standard (UHS-II available on slot 1 of the full-frame camera). However, a6400 is the only one with integrated flash.
+ A6400: 120.0mm x 66.9mm x 49.9mm; 403g with battery and memory card
+ A7 III: 126.9 x 95.6 x 62.7mm; 650g with battery and memory card
Viewfinder
The viewfinder of the smaller APS-C camera is 0.39 inches and has a smaller magnification of 0.7x. However, it has the advantage of a higher frame rate (up to 120 frames per second).
A7 III features a larger 0.5-inch OLED viewfinder with a magnification of 0.78x. The refresh rate is about 60 frames per second, and the resolution is the same for both (2.359k dots).
Screen
Both cameras have a 3-inch LCD screen with a resolution of 922k dots and touch sensitivity. The main difference is that the A6400 screen can tilt down 74° and up 180°, while the A7 III LCD screen tilts down 41° and up 107°.
Autofocus
A6400 has 425 phase-detection and contrast-detection autofocus points, covering 84% of the frame. Meanwhile, A7 III boasts a whopping 693 phase-detection points covering the entire frame, with 425 contrast-detection points alongside 4D Focus mode, making it easy to track fast-moving subjects.
Additionally, Sony has favored A6400 with two new features: “Real-time Eye AF” and “Real-time Tracking”. Real-time Eye AF is the latest upgrade of Sony's Eye AF technology, utilizing AI-based subject recognition to detect and track eyes, enhancing speed, accuracy, and performance. Real-time Tracking is a new object tracking feature, ensuring even the most unpredictable moving subjects stay in focus. These features will also be available on A7 III through a firmware update in April 2019.
Speed and Buffer
A6400 can shoot continuously at a maximum speed of 11 frames per second with AF and AE tracking.
A7 III is slightly slower, providing a maximum of 10 frames per second with continuous autofocus and auto exposure. If you switch to electronic shutter, the maximum speed remains the same.
For buffer memory, the official specifications suggest 99 JPG files or 46 RAW files. A7 III performs better with 163 JPG and 89 RAW files.
Video
Both cameras can shoot 4K video up to 30 frames per second using the full width of the sensor and performing full pixel readout (6K information is utilized and downsampled to 4K for increased sharpness).
At 1080p, both cameras can record up to 120 frames per second and you can choose to record at that speed in normal mode (with sound) or create slow-motion footage in-camera.
Both cameras have a 3.5mm microphone input, but only A7 III has a headphone output.
Battery Life
6400 uses NP-FW50 battery capable of shooting approximately 360 shots (viewfinder) or 410 shots (screen). Whereas A7 III uses the much larger NP-FZ1000 battery with a ratio of 610/710 shots.
Both cameras can be charged via USB, but only A7 III has an official battery grip.
Pricing
The price of the camera is clearly a crucial determining factor. A6400 starts at a retail price of 20 million VND for the body while A7 III is twice as expensive, around 46 million VND.
Conclusion
From the ability to shoot 4K video to improvements in autofocus and continuous shooting speed, a6400 stands tall against its larger sibling. It also has the advantage of being lighter and smaller for those seeking mobility. However, depending on finances, needs, and personal preferences, you can choose the camera that suits you best.
