Sony A6400 Review

Sony Alpha 6400 presented as successor to Alpha 6300: Mirrorless mid-range system camera

In this comprehensive review, we’ll get to the bottom of what the Alpha 6400 has to offer the photo community. We also follow Sony’s statement that the camera is the fastest APS-C camera in the world. A statement that has already been made about the Alpha 6300. Our own test laboratory was used to determine the image quality and provides information about what the photographer can expect from the image quality of the camera and the Sony E 18-135 mm 3.5-5.6 OSS and what not.

Sony Alpha 6400 with E 18-135 mm OSS. [Photo: Sony]

Short evaluation

Pros

• Fast tracking autofocus
• Extensive video functions
• Good detail reproduction up to ISO 6,400
• Fast high resolution electronic viewfinder

Cons

• Slow memory speed
• Touchscreen not fully implemented
• Spartan flash functions
• Low control options with the mobile app

With the Alpha 6400, Sony wants – once again – to have developed the fastest APS-C camera in the world. This title was already claimed by the predecessor model Alpha 6300 when it was unveiled almost three years ago. Although the APS-C sensor continues to resolve 24 megapixels and offers 425 phase and contrast AF sensors directly on the image sensor, covering a large part of the image field with 84 percent, focusing now takes only 0.02 (instead of 0.05) seconds, not least thanks to the new AI support. The continuous-advance function again achieves eleven frames per second including AF/AE tracking, but now for an exuberant 116 JPEG or 46 raw images in a row.

 

Although the Sony Alpha 6400 looks like its predecessor, the Alpha 6300, a lot has happened inside. Especially the autofocus is much faster again. [Photo: Sony]

Both photographers and videographers benefit from the new Bionz-X image processor, which is supposed to work 1.8 times faster than its predecessor, the Alpha 6300. A new feature is the front-end LSI, which not only provides a large serial image buffer, but also actively supports autofocus. He is particularly responsible for the AI functions. AI stands for Artifical Intelligence. A buzzword that has been circulating increasingly in the smartphone sector since last year and is intended to provide better pictures there. Thanks to this, the Alpha 6400 should in any case have a real-time autofocus with real-time tracking including a prediction of where the subject is heading. Not only eyes but also other motive details can be tracked, as long as they are selected, for example via the new touch screen. In the summer of 2019, Sony even plans to retrofit an animal eye recognition system with a firmware update, which should work just as well for house tigers as for animals in the wild.

Thanks to a special mechanism, the touch screen can now be raised by 180 degrees, which, according to Sony, is particularly helpful for so-called vloggers (video bloggers), who are better able to judge themselves or the image section when they are standing in front of the camera themselves and are at the same time the cameraman (or camerawoman) in the one-person team. The intelligent autofocus including intelligent tracking is also available for video recordings with 4K resolution and is intended to provide even better focusing for moving image recordings. The 6K oversampling of the 4K30p video recordings, which are stored in XAVC-S format at a high quality of 100 Mbps, ensures high image quality. The Alpha 6400 can handle HDR videos with HLG standard as well as S-Log2 and S-Log-3 gamma for video post-processing. Full HD videos are even possible with up to 120 frames per second for slow motion effects. An external microphone connection is just as important as the possibility to connect an XLR adapter.

A new feature is the touch screen that can be folded upwards by 180 degrees, so that Vlogger or Selfie photographers can keep an eye on the picture detail with the Sony Alpha 6400. [Photo: Sony]

Thanks to the multifunction flash shoe, not only system flashes can be attached to the Sony Alpha 6400, but also video lights or microphones. In addition, the Sony has a micro-USB socket with power supply and battery charging function. In addition, the housing is made of a magnesium alloy and should be sealed against the ingress of dust and splash water.

With its pure design and dimensions, the Alpha 6400 resembles its predecessor, the Alpha 6300, like an egg to an egg, so why change the tried and tested? On the other hand, there are new functions for operation, such as the graphical interface for assigning the eight function keys, each of which can be assigned one of 89 functions, or the My Menu. Also new is the touch functionality of the 16:9 screen, which measures 7.5 centimetres in the diagonal and has a resolution of 921,000 pixels. With a resolution of 2.36 million pixels and 0.7x magnification in 35mm equivalent, the OLED viewfinder also offers decent, albeit not groundbreaking, technical benchmarks. After all, the Alpha 6400 is a mid-range model despite its high performance.

The touchscreen of the Sony Alpha 6400 can still be folded down for shots across crowds. An XGA OLED viewfinder is also built in. [Photo: Sony]

The Alpha 6400 inherits its image processing algorithms from the top model Alpha 9, from which portrait shots in particular should benefit. Sony also wants to have improved the ISO performance. Not only the image quality at the same sensitivity is said to have improved compared to the predecessor model, but the standard sensitivity now reaches up to ISO 32,000 and the extended sensitivity even up to ISO 102,400.

In addition to eleven frames per second with the robust mechanical shutter designed for 200,000 releases, the Alpha 6400 can also photograph silently with an electronic shutter at up to eight frames per second, although the rolling shutter effect can distort fast-moving subjects. A new feature is the implemented interval recording function, which was only available as an option on earlier cameras for an extra charge via a camera app, but whose support Sony has not implemented in the latest camera models for a while now. However, the Alpha 6400 cannot compose a video from the interval recordings; the PC software supplied must be used for this purpose. The necessary wireless connectivity is provided by NFC, Bluetooth and WLAN, whereby Sony plans to release a new, improved app called “Imaging Edge Mobile” in March 2020.

The interface interface of the Sony Alpha 6400 offers a micro HDMI connection, a micro USB socket with USB charging function and an external microphone connection. [Photo: Sony]

Ergonomics and workmanship

For this review we had the Sony Alpha 6400 with the E 18-135 mm 3.5-5.6 OSS at our disposal. The first thing that catches the eye about the camera-lens combination is its small size. This is of course due to the camera measuring only 120 x 67 x 60 millimetres (width x height x depth), but the lens is also surprisingly small and handy despite its focal length. It measures just under 90 millimeters in length with a maximum diameter of about 70 millimeters. Thanks to the small lens diameter, the combination lies straight on the table, at least when the sun visor is not mounted. Whether the performance of the lens can also be convincing, we clarify in the section “image quality” a little further down in the text.

The case of the Sony Alpha 6400 is made of magnesium alloy. These types of alloys are low-vibration, stable and, above all, lightweight. Of course, the housing is not “naked”, but has been finished with a matt lacquer or veneered with various plastic parts, such as the grained rubber coating on the handle or the plastic veneer on the back of the camera.

Sony’s slogan for the Alpha 6400 is “durable construction even for demanding operating conditions”. For example, the housing should have a “moisture-repellent double structure”. In addition, “important” buttons and wheels are sealed. Unfortunately, there is no mention of which keys are important enough to have such a seal. The battery/memory card compartment and the connection terminal require no seals at all. So it’s better to treat the camera as if it wasn’t sealed at all.

The ergonomics of the handle is somewhat limited by the small housing size. Nevertheless, the camera is relatively easy to grip, even if the little finger of a medium-sized hand reaches into the yawning void on the underside. Sony has succeeded in arranging the control elements. The camera’s on/off switch is located directly on the shutter release button, and a function button can be assigned in the menu next to the shutter release button. The camera has a total of three rotating wheels. The corresponding and fully packed mode dial is located on the top of the camera and the second dial is right next to it. Depending on the selected operating mode, this has different tasks. Both wheels are shifted towards the back of the camera so that the photographer can easily make adjustments with his thumb. While the mode dial is very tight, the second upper dial is intentionally smooth.

The third and last rotary wheel encloses the control pad on the back. This turning wheel is also positioned in the immediate vicinity of the thumb. This all sounds great and will be ideal for many photographers. But if you want to take pictures with the manual mode, you have to do all the exposure settings with your thumb. Unfortunately, the thumb, like all other fingers, cannot be divided in two. So the photographer always has to reposition his thumb. The second rotary wheel would have been much better located at the front within reach of the index finger. But if you mainly use the semi-automatic machines or the program mode, then the whole thing won’t be very dramatic.

The other control elements on the back, on the other hand, are placed in a sensible position and provided with clear labels. The video trigger is somewhat hidden on the upper right corner of the camera. There is also a special feature in the form of a small toggle switch that encloses a button. Depending on the position of the toggle, the task of the enclosed key also changes. In addition to a large number of pre-assigned keys, the C1 and C2 keys can be assigned individually.

Fortunately, the Alpha 6400 has both a viewfinder and a touch screen. The viewfinder uses energy-saving OLED technology. The resolution is 2.36 million pixels. With the 0.7-fold magnification of the viewfinder, which is equivalent to a small picture, the view for spectacle wearers is unfortunately limited. Fortunately, the viewfinder has a diopter compensation (-4 to +3 diopters), but the mechanical adjustment is so unfortunate that the adjustment is quite fiddly. Here only longer fingernails help. The viewfinder image is clear and, thanks to a maximum of 120 frames per second, quite fast.

The monitor on the back of the Sony Alpha 6400 has a precise touch function, which unfortunately cannot be used for menu navigation. [Photo: Sony]

The 7.5 centimeter display can be folded 180 degrees upwards or 90 degrees downwards via a hinge. If you fold it all the way to the top, it becomes a self-adhesive display. Then one touch of the photographer is enough to count down a peppy countdown to the release. The monitor has a maximum luminance of 442 candelas per square meter in manual mode and 774 candelas per square meter in sunlight mode. So the display can still be used with this value even in really bright ambient light. For a camera with a 3:2 aspect ratio image sensor, the 16:9 aspect ratio of the screen is somewhat unfavorable, as this results in black edges that can be used for status displays but not for the live image, which is thus only displayed on a diagonal of about 6.6 centimeters.

The touch function of the display allows precise positioning of the AF measuring point. For much more, the touch screen is not usable, because unfortunately Sony has failed to integrate this extremely useful function into the menu navigation and recording control of the camera. Menus are thus navigated with the control pad or the setting wheels.

In any case, the menu is not very comprehensible in some areas. For example, if you want to move the autofocus from the shutter release button to another button, you must first remove the AF function from the shutter release button. The corresponding menu entry can be found in the fifth menu on the first tab. The assignment of the new key is then searched in vain in the settings menu, i.e. where one actually suspects the camera configuration. Instead, you can find the assignment of the keys on the eighth menu page in the second menu tab. This may also be confusing because the first three menu pages in the second tab are exclusively filled with video functions. Thus, one does not necessarily expect that configuration options for the photo mode can be found here as well. After all, in the Alpha 6400 the photographer can put together his own menu to his heart’s content, so that he can find the settings and functions he needs in one place and the annoying search in the menus is over.

In terms of power supply, the Sony Alpha 6400 is satisfied with a NP-FW50 lithium-ion battery. This should provide enough energy to take about 410 pictures when the display is used. This range was made by the manufacturer under conditions specified in the CIPA test procedure. During our test it was found that the battery is indeed very persistent. It is charged in the camera via the micro-USB interface. The camera is not choosy and also accepts universal USB power supplies and Powerbanks. The camera can also be used while attached to the AC adapter. Without a battery, however, it refuses to work, even if it is connected to a USB power supply.

The top of the Sony Alpha 6400 presents itself tidy and elegant. [Photo: Sony]

A micro HDMI interface is provided for connection to a television or external recorder. There is also a 3.5 mm jack socket for connecting an external stereo microphone, which even provides the necessary phantom power for active microphones. The interfaces are protected by a fixed sliding flap.

Recordings are stored on SDHC or SDXC memory cards. UHS-1 technology is also supported. The Alpha 6400 would not be a Sony camera without the MemoryStick and so the proprietary MemorySticks (Pro-HG Duo and Pro Duo) can also be used. How fast the memory cards should be, we clarify more exactly in the section equipment. As in the previous model, the battery and memory card share a cover on the underside of the camera. The distance between this flap and the tripod thread in the optical axis is large. This allows the battery or memory card to be changed easily, even when a quick release plate is attached to the camera.

Equipment

The Sony Alpha 6400 with the E 18-135 mm lens costs about 1,500 Euro (UVP) as a set and is aimed at the ambitious amateur photographer. Nevertheless, the camera has several automatic modes, which allow a fast and uncomplicated shooting. The camera can even analyze the subject before shooting and make the appropriate settings for shooting and image processing. If this is too much of a “black box” for you, you can fall back on the traditional scene mode functionalities, which the photographer must set to match the situation or “motive”. The camera has a total of nine scene modes for the most common scene situations.

The tripod thread of the Sony Alpha is located in the optical axis and is far enough away from the battery compartment. So the memory card can be changed easily on a tripod. [Photo: Sony]

However, the photographer does not have to fear a complete loss of control, as he can, among other things, perform the focusing himself. The focus loupe and focus peaking function, which highlights the contrasting edges of the image in colour, provide active support. The autofocus function works with 425 measuring points distributed over (almost) the entire image field. Only a small area at the left and right edge of the image is not covered. Autofocus is a hybrid AF system that incorporates fast phase comparison sensors and image contrast to determine the correct focus distance. Although the Alpha 6400 does not reach the focus speeds specified by Sony, the camera is still very fast, at least when the factory setting is used. Here, settings such as pre-autofocus and a function that creates a mixture of focus and shutter priority are active.

In the lab, the camera was able to safely adjust the focus in about 0.25 seconds at wide-angle. In the tele range it took a little longer with 0.46 seconds. If, however, the focus priority is activated, the wide-angle result changes significantly to 0.46 seconds and is thus on a par with the telephoto result. The pure release delay in both focal lengths was a rapid 0.03 seconds.

The strength of the autofocus system is demonstrated by the continuous autofocus, as with the predecessor model Alpha 6300. This enables the camera to maintain subject tracking at the highest frame rate of eleven frames per second. In the continuous-advance mode, the camera takes a maximum of 102 consecutive shots; in the raw data mode, instead of JPEG, the number of shots is reduced to 47 before the buffer is full. The recording frequency then drops to about 1.7 frames per second. To clear the buffer, the camera then writes data to the memory card at about 41 megabytes per second and takes about 25 seconds to clear the entire buffer. During this time, however, the camera remains ready for use. Thus, the Alpha 6400 remains true to the Sony tradition of being equipped with a large buffer memory, but shovelling the data onto the SD card at a rather slow storage speed.

In addition to the automatic functions, the photographer can also choose to use the Alpha 6400 manually or semi-automatically. It also offers bracketing functions for white balance and automatic contrast enhancement (DRO). In addition, there are exposure bracketing functions for single and continuous shots. The maximum spread for both is three EV with five shots. Also an extensively equipped interval function is part of the game. This allows a start delay of up to about 100 minutes, interval lengths of up to 60 seconds, autofocus sensitivities and much more to be programmed.

Although the E 18-135 mm OSS on the compact Sony Alpha 6400 looks a bit massive, the combination is pleasant to use. [Photo: Sony]

The Alpha 6400 uses a traditional mechanical focal-plane shutter with a minimum exposure time of 1/4,000 seconds. Although the camera is able to simulate the first shutter curtain electronically and to take a “silent” picture only with an electronic shutter, this does not change the shortest possible shutter speed. There is no electronic shutter with 1/16,000 or 1/32,000 second shutter speed as with other manufacturers.

Also the flash sync time is not very fast with 1/160 second. The integrated pop-up flash has a measured guide number of 7.6 and is thus slightly above the figure Sony states in the data sheet. The integrated flash can unfortunately not be used to control external system flashes. Fortunately, the camera has a Sony multi-interface connector to which compatible system flash units can be attached. The mechanical switch for unfolding the flash unit is positioned somewhat unfavourably. The switch is covered by the monitor when it is folded upwards by more than 90 degrees.

With a maximum resolution of 3,840 x 2,160 pixels and a frame rate of 30 frames per second, the Alpha 6400 4K records video at a bit rate of up to 100 Mbps. This is quite respectable and above all not the end of the video function flagpole. As with the photos, so-called “Picture Profiles” can also be used for video recordings. Picture Profiles are presets of color and gradation settings. Among the Picture Styles for video recordings there are three HLG profiles. HLG stands for “Hybrid Log Gamma”, which enables the recording of a higher brightness range. However, these HDR videos can only reach their full potential on HLG-compatible televisions. The advantage of the HLG profiles is that the videos are backward compatible with non-HDR-compatible TV sets, in contrast to videos recorded with HDR10, for example. However, the brightness range that an HDR10 signal can provide is greater.

Like the Alpha 6300, the Alpha 6400 also reads the complete sensor for video recording, which corresponds to a 6K signal source with a 2.4-fold overscan – at least if the frame rate is 24 fps. At 30 fps “only” a 1.6-fold overscan of the sensor takes place. The built-in stereo microphone can be controlled automatically or manually. Those who prefer to connect an external microphone can do so via a 3.5 mm stereo jack plug. As in the Alpha 6300, the HDMI connection can be used to transfer the sensor data to an external recorder and have it record.

On the right side of the Sony Alpha 6400 you can see the logo referring to the NFC antenna. [Photo: Clara Andersson]

The left side of the Sony Alpha 6400 shows the unsealed flap covering the connection terminal (for Micro-USB, Micro-HDMI and 3.5 mm stereo jack microphone). [Photo: Clara Andersson]

In our test of the Alpha 6300, we criticized the autofocus, which at times did not work in video mode. The Sony Alpha 6400 no longer has this problem. Thanks to various adjustment options, the videographer can adjust the sensitivity and responsiveness of the autofocus system. Thus, the behavior of the autofocus can always be precisely adapted to the existing subject situation. In the various shooting situations, the autofocus has proven to be very precise and fast.

Since the Alpha 6400 has no stabilizer in the housing, it has to rely on stabilization systems housed in the lens. Since we tested the camera with the Sony E 18-135 mm 3.5-5.6 OSS, we were able to judge the stabilizer in the lens. This has shown that it can easily compensate for almost three f-stops. Exposure times at 135 mm focal length are easily possible up to 1/60 second.

The connectivity of the camera is extensive. For example, an energy-saving Bluetooth function and the less economical but more powerful WLAN function are available. To use these, a free app must be installed on the smart device to be connected. The “Imaging Edge Mobile” app for iOS and Android is available for free download in the respective shops (itunes and PlayStore). The app is the direct successor of the PlayMemories app.

The bayonet of the Sony Alpha 6400 is made of metal, as are parts of the case. [Photo: Sony]

Pairing device and app is quite simple and the camera guides the photographer through this process if desired. In addition to a simple remote trigger, an extensive remote control with Live View can also be activated. Of course, image data can also be transferred from the camera to the app. The permanent connection with the smart device for the transmission of position data is also possible without any problems via Bluetooth. In addition, the camera can be integrated into a wireless network, whereupon it can be controlled with the “Image Edge” Desktop App, transferring images and converting raw data. The remote control function of the app is fine, but could be more extensive in the settings options. The camera itself is rather sparsely equipped with image processing functions. Not even raw images can be converted to JPEG in playback mode.

Picture quality

The Sony Alpha 6400 succeeds in teasing more usable resolution out of the nominally 24 megapixel APS-C sensor than its predecessor, at least in the middle of the picture. At 50 percent contrast, the camera achieves almost 67 line pairs per millimeter (lp/mm) in 35mm equivalent. Towards the edge of the picture, however, the resolution of the 18-135mm lens used drops by more than 50 percent. Only by closing the aperture can the difference between the center and the edge of the image be reduced, but this also reduces the maximum resolution. The lens thus shows similar performance as a lens of a bridge camera. When focusing, the camera holds itself back, so that only minor sharpening artifacts appear in the image.

The edge darkening (vignetting) is below one f-stop in all focal lengths with open aperture and is therefore low. The camera-lens combination also makes a good impression when it comes to distortion. The wide angle shows a small barrel-shaped distortion and the medium focal length a slightly cushion-shaped distortion. Even in the maximum tele we have detected an extremely low barrel distortion. The average transverse chromatic aberrations are also low. These errors are most visible in the telephoto range and the medium focal length.

With the Sony Alpha 6400, the memory card and battery share a compartment and a cover. [Photo: Sony]

The detail reproduction is good despite the mediocre signal-to-noise ratio. Fine details can be seen in the image up to ISO 6,400, although the luminance noise becomes visible from ISO 1,600. Disturbing color noise, on the other hand, is not a problem with any ISO sensitivity. The input dynamic is high up to ISO 12,800, but drops rapidly above that. The output tonal range is good up to ISO 400 and acceptable up to ISO 6,400.

The colour reproduction of the Alpha 6400 is good, even if especially bright green-yellow, orange and red-magenta are somewhat dampened. The color depth is good with slightly more than 22 bits at ISO 100. This corresponds to more than 4.2 million colors. Up to ISO 6.400, the color depth decreases, but remains within the good range. At higher ISO levels, the color depth is within an acceptable range.

Bottom line

With the Alpha 6400, Sony has brought a worthy successor to the Alpha 6300 onto the market and thereby eliminated many criticisms of the predecessor model. Autofocus is fast even when tracking in continuous advance mode. The camera fulfils everything that beginners and ambitious photographers expect. The Alpha 6400 also has to put up with the bottleneck of memory speed that is typical for Sony, even though the camera is not completely unusable during saving. However, the very good impression is clouded by the “Wischi-Waschi” dust and splash water protection, which is obviously nothing more than an advertising slogan.

Sony connoisseurs will quickly get to grips with the menu structure for camera configuration. It may take some time to learn the menu structure, which is often very individual. In terms of image quality, the Alpha 6400 delivers a good resolution as well as good color depth and the noise behavior is also fine. The Alpha 6400 is therefore a great camera for beginners and those who change their camera, who not only have fast, uncomplicated photography but also greater photographic and videographic ambitions.

Firmware update 2.00 for the Sony Alpha 6400: Focuses now also on animal eyes

Sony now offers since 2020 the firmware update with animal eye recognition for the Alpha 6400, which was promised at its launch in January 2019. In addition, the firmware update 2.00 ensures compatibility with the Bluetooth remote control RMT-P1BT announced at the end of February 2019 and fixes some minor software stability problems of the camera. The new camera operating software can be downloaded from the support area of the Sony website and installed on your own using the instructions provided there. If you don’t have the confidence to do it yourself, ask your dealer or Sony support for help.

The animal eye AF of the Sony Alpha 6400 focuses on the eyes of various animals, here a dog, ensuring perfect focus. [Photo: Sony]

The animal eye AF of the Sony Alpha 6400 can also focus on the eyes of a fox after the firmware update 2.00. [Photo: Sony]

Cats are not to be missed beside dogs and wild animals of course. The animal eye AF of the Sony Alpha 6400 also recognizes their eyes without any problems. [Photo: Sony]

In the meantime we have also received a press release from the local Sony representatives. In it Sony shows some example pictures, of which a few can now be seen here. The animal eye autofocus works like the human eye autofocus in real time, i.e. the camera can keep the eyes in focus in the AF-C or during subject tracking. A combination with the silent release is also possible. Previously, only the full-frame Sony Alpha 7 III and Alpha 7R III models had animal-eye autofocus, making the Alpha 6400 the first APS-C model to feature this advanced technology. A corresponding firmware update for the Alpha 9 will followed also middle of 2020.

Sony Alpha 6400 Datasheet