While we’re living through a flurry of activity around full-frame mirrorless cameras, there’s still a strong case to be made for APS-C format sensors. Sony’s latest addition to its a6000 series joins Sony’s APS-C mirrorless lineup just below the flagship a6500. While it lacks the a6500’s in-camera stabilization, it boasts a number of features that its premium-priced sibling lacks.

Features

The a6400’s primary advantage over its peers is autofocusing. According to Sony, it has the fastest autofocus acquisition in the world at .02 seconds. Additionally, it marks the introduction of a pair of new autofocusing features: Real-time Eye AF and Real-time Tracking (features which have subsequently been added to Sony’s a7R III, a9 and a7 III via firmware upgrades and to newer Sony bodies out of the box).

The new Real-time Eye AF employs artificial intelligence-based object recognition to detect and process eye data in real time, which Sony says improves accuracy, speed and tracking performance when shooting in Eye AF. In all autofocus modes, the camera automatically detects the eyes of the subject and activates Eye AF with a half press of the shutter button. When you’re shooting in AF-C or AF-A mode, you can choose which eye you would like to make your focus point.

Also debuting on the a6400 is “Real-time Tracking” which also employs AI-based object recognition and processes color, subject distance (depth), pattern (brightness) as spatial information to ensure that all subjects can be captured accurately.

As far as AF points go, the a6400 has plenty. There are 425 phase-detection AF points and 425 contrast-detection AF points covering approximately 84 percent of the sensor.

Beyond speedy AF, the a6400 sports a 24-megapixel image sensor with a top native ISO of 32,000 (expandable to 102,400). It’s capable of shooting at 11fps with AF/AE tracking using a mechanical shutter or up to 8fps with an electronic shutter. You can shoot up to 116 JPEGs or 46 compressed RAW files in continuous mode.

On the video front, the a6400 can record 4K/30p (3840 x 2160) with full pixel readout and no pixel binning. You can also record full HD at up to 120 fps. The camera supports Sony’s cine-friendly profiles, including S-Log2/3, HLG, Gamma (Cine1-4) and more. It also has a built-in intervalometer, a first for Sony’s a6000 series.

The a6400 retains the same utilitarian design as its predecessors. That’s a good thing.

Design

We’ve always been a fan of the a6000’s functional design. It lacks
the head-turning esthetics of rivals like Fujifilm or the nostalgia-infused approach taken by cameras like the Olympus Pen, but with ample options for customization, large buttons and a responsive touchscreen, it offers a very streamlined and intuitive shooting experience. The only thing it lacks is an AF-selecting joystick, which would have been super useful.

There’s a 3-inch, 180-degree tilting touchscreen display that supports touch focusing and shutter release, and a Touch Tracking mode which activates the camera’s Real-time Tracking function. Unfortunately, you can’t use touch to navigate the menu.

You can also frame your scene through an XGA OLED viewfinder. It’s somewhat small, but very crisp and responsive.

At 14.3 ounces it’s a tad heavier than rivals like Fujifilm’s X-T30. There’s a single, bottom-loading SD card slot for UHS-I cards.

Image Quality & Performance

The a6400 continues in the footsteps of its predecessors in offering first-rate still and video image quality. Noise is very well contained in JPEG images through ISO 6400 and fine details reproduced quite well. We didn’t really miss the lack of in-camera stabilization when shooting stills, but its absence will be more noticeable during video recording.

Subjectively, color reproduction looked excellent, though Image Engineering did catch the camera struggling the most with reds (of the camera’s six strong color deviations, five were red tones).

If you’ve seen videos of Sony’s AF wizardry in action, you’ll know that the company has indeed made great strides in tenacious tracking. The a6400 continues the tradition, delivering the best autofocusing we’ve seen for a camera in this class. That said, the Real-time Tracking system isn’t flawless. For one subject, Eye AF would frequently settle its floating green square on a forehead, an issue that seemed to pop up when shooting within three feet of a face, but not further back. On balance, though, the new autofocusing skills works as advertised. The AF tracking makes the a6400 an extremely attractive option for anyone who needs to lock in on rapidly moving subjects.

Earlier versions of the a6000 had set a benchmark for burst shooting. The a6400 doesn’t advance the ball on that front, delivering the same brisk 11 fps in continuous shooting with AF tracking engaged. Here too, the a6400’s system does an excellent job in keeping subjects in focus across dozens of rapid-fire frames. However, it’s not as fast as Fujifilm’s X-T30, which can clock in at 20 fps using an electronic shutter (you can go even faster if you switch to a crop mode).

Sony has made huge strides in improving the battery life of its a7 series models, but sadly the a6400 isn’t the beneficiary of that progress. Battery life clocks in at a respectable 370 shots, per CIPA standards, which is on par with the X-T30.

Bottom Line

If you’re in the market for a highly capable APS-C, the a6400 should be at the top of your list. While we missed in-body stabilization, its class-leading autofocusing, utilitarian design and excellent image quality are a compelling combination.

Sony a6400

Pros: Class-leading autofocusing; excellent image quality; solid
color reproduction.
Cons: Flip-up display interferes with hot-shoe accessories; no in-body stabilization.
Price: $900
Info: sony.com

PDN is a member of the Technical Image Press Association which has contracted with Image Engineering to perform detailed lab tests of digital cameras. See here for a full methodological rundown of how Image Engineering puts cameras through their paces. Full res files of every visual in this review are available to download for your pixel-peeping pleasure here. 

INTRODUCTION

Based on the numbering and the $900 price point, the a6400 comes in a bit below the a6500–it lacks the in-body image stabilization of its higher-priced peer, but also packs a host of new features not found on the a6500.

According to Sony, the a6400 will offer the world’s fastest autofocus acquisition at .02 seconds. Additionally it marks the introduction of a pair of new autofocusing features: Real-time Eye AF and Real-time Tracking. More on that below.

The a6400 sports a 24-megapixel image sensor with a top native ISO of 32,000 (expandable to 102,400). It’s capable of shooting at 11fps with AF/AE tracking using a mechanical shutter or up to 8fps with an electronic shutter. You can shoot up to 116 JPEGs or 46 compressed RAW files in continuous mode.

There’s a 3-inch, 180-degree tilting touch screen display that supports touch focusing and shutter release and a Touch Tracking mode which activates the camera’s “Real-time Tracking” mode. You can also frame your scene through an XGA OLED viewfinder.

AUTOFOCUSING

The a6400 features 425 phase-detection AF points and 425 contrast-detection AF points covering approximately 84 percent of the sensor.

The new Real-time Eye AF employs artificial intelligence-based object recognition to detect and process eye data in real time, which Sony says improves accuracy, speed and tracking performance when shooting in Eye AF. In all autofocus modes, the camera  automatically detects the eyes of the subject and activates Eye AF with a half press of the shutter button. When you’re shooting in AF-C or AF-A mode, you can choose which eye you’d like to make your focus point.

For now, the a6400 can only track human eyes but Sony says a coming firmware update will enable Eye AF for animals, too.

Also debuting on the a6400 is “Real-time Tracking” which also employes AI-based object recognition and processes color, subject distance (depth), pattern (brightness) as spatial information to ensure that all subjects can be captured accurately.

VIDEO

On the video front, the a6400 can record 4K (3840 x 2160)  with full pixel readout and no pixel binning. You can also record full HD at up to 120 fps.

Sony says they’ve updated the Fast Hybrid AF system used during video recording to improve AF accuracy. This will be Sony’s first camera to support a Hybrid Log Gamma picture profile for HDR filmmaking. S-Log2/3 profiles, Zebra stripes and a Gamma Display assist feature are also available.

There’s also a built-in intervalometer for time-lapse shooting that’s capable of recording up to 9,999 images at intervals between 1 and 60 seconds.

Additional features include:

• 8 custom keys
• new help screen
• the ability to add star ratings to images
• a shutter rated for 200,000 cycles
• 360 shot battery life

The a6400 is available now for $900.

Resolution   

• At ISO 100, captures 1929 line pairs per picture height (LP/PH), reaching 96% of the theoretical maximum.
• In comparison, the predecessor Sony Alpha 6300 captured 1892 LP/PH (95%), at ISO 100, and the Alpha 6500 1885 LP/PH, 94% of the theoretical maximum.
• Another recent Sony, the Alpha 7 Mark III, reached 98% of the theoretical maximum of its 24-megapixel sensor at ISO 100 (1964 LP/PH).
• Resolution in the Alpha 6400 is very consistent: 94% of the theoretical maximum at ISO 800 (1882 LP/PH) and 95% at ISO 1600 (1891 LP/PH); at ISO6400, 91% of the theoretical maximum (1812 LP/PH).
• Sony Alpha 6300 recorded 1738 LP/PH (87%) at ISO 1600.
• The higher ISOs of the Alpha 6400 show less good resolution but cannot be described as poor: e.g. at ISO 12800, it captures 85% of the theoretical maximum with 1699 LP/PH.

This graph shows the loss of contrast (y-axis) as a function of the spatial frequency in line pairs per picture height (x-axis) for different ISO-sensitivities (colored lines). The further to the right a curve stretches before descending, the better the resolution at that ISO.
The limiting resolution for each ISO can be found by identifying to the highest spatial frequency which results in a contrast of 0.1, or where the ISO curve crosses the thicker horizontal thicker black line marking 0.1. The vertical pink line is a reference representing half the number of pixels in the sensor height (the Nyquist frequency).

Texture loss

• MTF50 is generally better (except at ISO 100 in high-contrast areas) than the older Alpha 6300, but the proportion of artifacts is higher.
• Texture loss results for the Alpha 6400 show an MTF50 of 1282 LP/PH at ISO 100 with 22.3% artifacts in areas of high contrast, and a slightly higher MTF50 (1339 LP/PH) with more artifacts (29.2%) in areas of low contrast.
• At the same ISO of 100, the Alpha 6300 showed an MTF50 of 1334 LP/PH with only 16.0% artifacts in high-contrast areas, and 1271 LP/PH with a low 5.1% artifacts in low-contrast areas.
• Texture reproduction in high-contrast areas is better both at ISO 400 and at ISO 800 (MTF50 1356 and 1307 LP/PH, respectively, with 22.9% and 26.0% artifacts) than at ISO 100.
• At ISO 400 in low contrast: 1339 LP/PH and 28.2% artifacts at ISO 400, and 1195 LP/PH with 36.4% artifacts at ISO 800.
• The Alpha 6300 recorded 1223 LP/PH and 1113 LP/PH in high contrast at the same ISOs, with 19.7% and 20.5% artifacts, respectively. In low-contrast areas, the 6300 did not perform well: 1182 LP/PH with 11.6% artifacts at ISO 400, and a rather poor 866 LP/PH with 11.4% artifacts at ISO 800.
• At ISO 3200, texture is not very well reproduced by the Alpha 6400: MTF50 is 927 LP/PH with 38.9% artifacts (high-contrast parts of the scene). In low-contrast areas, MTF50 at ISO 3200 is 728 LP/PH with many artifacts (52.3%).
• The Alpha 6500, in comparison, at ISO 3200 showed a similar MTF50 of 928 LP/PH combined with fewer artifacts (18.7%) in high-contrast scenes, and 635 LP/PH, with 17.0% artifacts in areas of low contrast.
• At ISO 6400, MTF50 in high-contrast areas is 932 LP/PH with 44.1% artifacts, combined with an MTF50 of 529 LP/PH with 60.6% artifacts in low-contrast parts of the scene.

An artifact is an alteration in a digital image due to technology or technique of processing. Artifacts stem from noise, compression, and sharpening. This graph plots the calculated difference in digital signal between two methods (DeadLeavesCross & DeadLeavesDirect). The colored lines represent response at different ISOs and in reference to a high-contrast target and a low-contrast target. Values plotted are the Dead Leaves SFR difference against the spatial frequency. The larger the area under the curve, the more artifacts are present.

 Edge contrast / sharpening   

• Small amount of overshoot and a slightly larger proportion of undershoot to high-contrast edges: at ISO100, 2.0% overshoot and 5.1% undershoot.
• Sharpening is greater albeit still moderate along low-contrast edges: e.g. at ISO 100, 4.7% overshoot and 9.0% undershoot.
• The degree of sharpening remains consistent as ISO increases: for example, at ISO 800, overshoot is 1.8% and undershoot 5.6% (high contrast), and 4.9% overshoot and 7.5% undershoot along low-contrast edges.
• At ISO 3200, sharpening is stronger (3.7% overshoot and 8.0% undershoot along high-contrast edges; 7.5% overshoot and 9.9% undershoot along low-contrast edges).

This graph shows the degree of sharpening in the image by representing an over- and undershoot along contrasted edges. The colored lines represent measurements at different ISOs and in high- and low-contrast situations. The size of the dip before the edge (in both depth and breadth) indicates the degree of undershoot; similarly, the amount overshoot is indicated by the height and breadth of the peak. Thus, larger dips and/or peaks indicate that a sharpening effect is visible.

OECF VN / visual noise    

• Images made by the Sony Alpha 6400 at ISO 100 would not show visible noise even when viewed at 100% enlargement (VN1).
• At higher ISOs, however, visual noise would be start to be noticeable from ISO 400 in VN1 (score 1.2), become obvious at ISO 3200 (2.0), and disturbing by ISO 12800 (3.0).
• Extended ISOs would show a lot of noise: e.g. a score of 5.7 at ISO 51200.
• Visual noise would have been a little less obvious in VN1 at nearly all ISO speeds for the older Alpha 6300 (e.g. score 1.1 at ISO 400 and 1.9 at ISO 3200).
• In VN2 and VN3, the Sony 6400 performs slightly better than its predecessor at all ISO speeds tested up to and including ISO 25600.
• VN2: no noticeable noise at any of the native ISOs. Only at extended ISO 12800 would noise be observable (score 1.3, VN2).
• VN3: Sony Alpha 6400 produces images with visual noise scores below the threshold of being observable at all ISOs up to ISO 3200 (score 0.8). At ISO 6400, the noise would be noticeable but noise only becomes very obvious at ISO 25600 (score 2.3).
  

  This chart shows the noise behavior at various ISO-sensitivities (colored lines) as a function of the brightness of the target image, which is indicated by the relative darkness of the circle on the outer edge of the diagram (noise in shadowed areas are above, and in highlights below). The larger the area inside a curve, the stronger the noise.
  The degree to which noise disturbs the appreciation of an image, depends on the image size and the viewing condition. The right-hand side of the chart shows the visibility of the noise in an image that is displayed 100% on a monitor (VN1). The left-hand half shows the visibility of noise in a 40-cm tall print (VN3).

  

  This chart shows the noise behavior at various ISO-sensitivities (colored lines) as a function of the brightness of the target image. The perception of noise is represented by the area that is encircled by the curve. The larger the area, the stronger the noise. How much the noise disturbs the viewing of an image, depends on the image size and the viewing distance. This chart shows the noise visibility for an image that is displayed 100% on a monitor (VN1).

  

  This chart shows the noise behavior at various ISO-sensitivities (colored lines) as a function of the brightness of the target image. The perception of noise is represented by the area that is encircled by the curve. The larger the area, the stronger the noise. How much the noise disturbs the viewing of an image, depends on the image size and the viewing distance. The chart shows the noise visibility for an image that is about postcard size (scaled to a height of 10cm) viewed at a distance of 25cm.

Dynamic Range      

• Dynamic range is good in the Sony Alpha 6400: at ISO 100, 10.6 f-stops.
• At ISO 400, 9.8 f-stops, and at ISO 800, 9.1 f-stops.
• From ISO 1600, dynamic range is less good: 8.8 and 8.7 f-stops at ISO 1600 and 3200, respectively.
• At ISO 6400, dynamic range is 8.0 f-stops. At the top extended ISO (ISO 102400), it is 5.6 f-stops.
• Don’t Miss the Best Cameras for Dynamic Range

Color Reproduction

• Color reproduction is very good, with only 6 colors deviating strongly from the original.
• ∆E ranges around 9.0 or 9.1 at ISOs 100 to 1600, and also at ISO 6400.
• At the top native ISO, 3200, ∆E is slightly better at 8.8.
• This is better than the Alpha 6300, which showed a ∆E of 11.5 and above.
• Don’t Miss the Best Cameras for Color Reproduction

Color reproduction is shown here in two ways. The upper figure is a chart comparing a reference color (right-hand half of each color patch) directly with the color reproduced by the camera (left-hand half of the color patch)
Below is a table that lists the DeltaE of each color patch. Red cells indicated strong color deviations, light green cells represent colors with noticeable deviations, and a dark green field represents a moderate deviation.

 Automatic white balance

• The automatic white balance is excellent, with values at 0.0 or 0.1 at ISOs 400 to ISO3200.
• At ISOs 100 and 6400, automatic white balance is still excellent at 0.2.

Video                                                                

• Resolution in video shot at ISO 100 is 1209 LP/PH, 112 percent of the theoretical maximum, and at ISO 1600, 1158 LP/PH, 107% of the theoretical maximum.
• The Sony Alpha 6300 produced videos with very similar resolution results: 1225 LP/PH (113% of the theoretical maximum) at ISO 100, and 1183 LP/PH (110%) at ISO 1600.
• The Alpha 6400 produces an MTF50 of the Deadleaves pattern (high contrast) of 1080 LP/PH with 26.7% artifacts in frames grabbed from video shot at ISO 100, and 991 LP/PH with 21.2% artifacts in low contrast.
• Better than the Alpha 6300, which produced an MTF50 of 844 LP/PH with 28.4% artifacts in high contrast, and 850 LP/PH with 21.5% artifacts.
• In videos shot with the Alpha 6400 at ISO 1600, these values are 787 LP/H with 38.9% artifacts (high contrast), and 739 LP/PH with 38.7% artifacts (low contrast).
• Sharpening is stronger in video made by the Alpha 6400 than in still images.
• Visual noise would be noticeable in video images viewed at 100% (VN1; scores are a noticeable 1.3 at ISO100, and an obvious 2.4 at ISO 1600).
• Noise would not be visible in videos shot using the 6400 at ISO 100 when viewed either on a small mobile screen or as a large print (VN2 and VN3).
• Some noise would be visible in the ISO 1600 videos in both VN2 and VN3, albeit not enough to disturb the viewing of the image.
• Dynamic range in video is 8.7 f-stops at ISO 100 and 8.0 at ISO 1600. The 6300 has a dynamic range of 8.3 f-stops at ISO 100 and 8.0 at ISO 1600.
• Automatic white balance in video is poorer than for still photography: 0.9 at IO 100 and 1.0 at ISO 1600.

Start-up time          

• The camera starts up in 1.4 seconds.

Continuous shooting        

• The Alpha 6400 records 11.1 frames per second until the card is full in JPEG, and the same speed for a total of 47 RAWs.
• The speed of burst shooting was the same in the Sony Alpha 6300, 11.1 frames per second in both JPEG and RAW.

Autofocus (300lx) Live View       

• Focus and shutter release in bright light takes 0.5 of a second, of which the shutter lag is 0.03 of a second.

Autofocus (30lx) Live View         

• Autofocus and shutter release time are the same in low light: 0.5 of a second in total.

The speed of autofocus (orange) in high and low light conditions. The green portion of each bar represents the shutter time lag, which is the time (in seconds) between depression of the release button and the start of the exposure with a camera that is already focused on the target. It excludes the time required to focus on the subject. The height of each bar represents the total shooting release time lag: autofocus and shutter time lag together

Handling

Body & Buttons     

• Body is fairly small and light, and feels robust.
• Plain front; a number of buttons, dials, and labels are crowded onto the back of the camera next to the proportionately large monitor.
• The grip surface feels like real rubber and offers a good grip.
• One obviously customizable button (C1 near the shutter release button), but the menu offers options to customize two additional buttons (and one on the lens) for still photography or video.
• The drive modes include a MR option, which allows one to select from three recalled options and four which can be set in advance in the menu. For some users who can predict some of the different shooting options, this could be an invaluable feature.

Display and Viewfinder    

• The monitor’s shape indicates this camera is aimed at users who shoot video, as it has an approximate proportion of 16:9 (some portions are used for the menu but not for image display).
• Monitor tilts upward to 180 degrees so it could be used for selfies or video bloggers.
• Rich colors in bright light seem to look more vibrant in the viewfinder that the scene does to one’s eyes.
• Diopter is a flat wheel (rather than partially embedded dial).
• The electronic viewfinder is easy to use and not glaring.

Menu structure

• The main menu can be set to open with a series of pictograph ‘tiles’, which permitting quicker access to some submenus than the default list.
• Once programmed, the customizable ‘my menu’ can be used for rapid access to no fewer than 30 items.
• Quick settings are very accessible both via the ‘display’ button which switches between different display options, and directly via the Fn button, which shows a short menu of 12 items below the image preview on the monitor.
• These menus can also be navigated with buttons and wheels while viewing them through the viewfinder.
• No touch control for main menu navigation.
• Five function buttons and twelve items in the quick menu can be customized.

Functionality

• Zebra, peaking, and focus magnification, as well as composition aids offered.
• The switch on the upper righthand side of the camera rear, allows one to use autofocus even when manual focus is selected.
• Turning the focus ring on the lens activates the loupe to facilitate manual focus, even when the focus mode is set to autofocus.
• The flexible spot AF can be moved using touch on the monitor.
• One can choose in the menu that the focus point does not ‘circulate’ and so remains at the same location with multiple half-presses of the shutter button.
• ‘Real time tracking’ is said to show good follow-autofocus characteristics.
• ‘Focus point link’ spot metering offered.
• Although the native ISO can go up to 32000, the auto ISO mode tends towards lowest ISOs.
• Time lapse shooting is offered in-camera.
• Records in RAW as well as JPEG. RAWs are compressed and in 14-bit unless captured in certain conditions such as bulb mode.
• The camera body lacks an internal image stabilizer.
• Some functions can only be set when more than one control is changed: so, for example, the silent shooting option only controls the shutter (sounds) and the autofocus beep must be turned off elsewhere.
• Default touch function while shooting on the monitor is focus: to activate touch shutter requires changing two settings in different parts of the main menu.

Special features     

• Firmware update planned for summer 2019 should enable eye-detection in mammals (and possibly birds), presumably helping wildlife and pet photographers.
• Silent shooting is available, although the Help Guide points out that the autofocus and aperture settings will also create noise and so the shots may not be entirely silent.
• Hybrid AF: 425 AF points for phase AF and also 425 for contrast AF.
• Option for choosing the type of scene automatic oneself, with a small icon in the upper right showing whether one can selected fast-moving sports, sunset, or macro images, for example.
• Animal eye detection is said to be forthcoming in a firmware update.
• One can also set multi (matrix) metering to prioritize faces, which could be very useful for quick travel or family photos.

IN DEPTH

The launch of the Sony Alpha 6400, a new camera with a model number sandwiched between those of two existing cameras – the Alpha 6300 and 6500 – has puzzled some observers. The Alpha 6400 contains some improvements on the older cameras but also lacks some features the Alpha 6500 had. The Alpha 6400 thus seems to be an upgrade of the Alpha 6300.

All three cameras have APS-C sensors with a pixel count of 24 megapixels. At ISO 100, the Sony Alpha 6400 uses its sensor fairly well, capturing 1929 line pairs per picture height (LP/PH), 96 percent of the theoretical maximum. Both the Sony Alpha 6300 and the 6500 showed similarly good resolution at ISO 100.

The resolution in the Alpha 6400 camera is also consistent: 94 percent of the theoretical maximum at ISO 800 and 95 percent at ISO 1600. Even images made at ISO 6400 by the Alpha 6400 still reach 91 percent of the theoretical maximum. The higher ISO s do less well but cannot be described as poor: e.g. at ISO 12800, it captures 85 percent of the theoretical maximum with 1699 LP/PH. The predecessor Sony Alpha 6300 showed more of a decline in resolution with higher ISO .

With consideration of texture loss, the newer Alpha 6400 shows generally better results than the Alpha 6300 but also a lot more artifacts. Somewhat counterintuitively, texture reproduction by the Alpha 6400 in high-contrast areas is better at higher ISO s (ISO 400 and at ISO 800) than at ISO 100.

Sharpening is moderately applied by the Sony Alpha 6400. The camera generally adds a small amount of overshoot and a slightly larger proportion of undershoot to high-contrast edges: at ISO 100, for example, 2.0 percent overshoot and 5.1 percent undershoot. Sharpening is greater albeit still moderate along low-contrast edges: e.g. at ISO 100, 4.7 percent overshoot and 9.0 percent undershoot. The degree of sharpening remains consistent at edge interfaces as ISO  increases.

Noise can be an issue in digital imaging, especially in cameras with small-sized sensors. Images made by the Sony Alpha 6400 at the lowest ISO  (100) would not show visible noise even when viewed at 100 percent enlargement. However, already by ISO 400, visual noise would be observable when viewed at 100 percent. The proportion of noise visible would increase to ‘obvious’ at ISO 3200 (score 2.0), and to a level that would disturb enjoyment of the image by ISO 12800. The Alpha 6300 showed even less noise, the difference is small.

The Alpha 6400 performs slightly better than its predecessor at all ISO  speeds tested up to and including ISO 25600 in Viewing Conditions 2 and 3 (VN2 and VN3). In Viewing Condition 2, modelling viewing a small mobile screen or postcard-sized print, an image made by the Sony Alpha 6400 would exhibit very little visual noise.

In Viewing Condition 3, which models viewing the image as a large print, no noise would be observable in photos made by the Alpha 6400 up to ISO 6400.

Dynamic range is good in the Sony Alpha 6400 at the lower ISO S: at ISO 100, 10.6 f-stops. In comparison, the Sony Alpha 6300 showed a peak dynamic range of 10.7 f-stops at ISO 400. In the Alpha 6400, dynamic range is less good at higher ISO s: for example, 8.8 f-stops at ISO 1600.

Color reproduction is very good, with only 6 colors deviating strongly from the original. ∆E ranges around 9.0 or 9.1 at ISO s 100 to 1600, and also at ISO 6400. This is better than the Alpha 6300, which showed ∆Es of 11.5 and above.

The automatic white balance by the Alpha 6400 is superb, with values at 0.0 or 0.1 at ISO s 400 to ISO 3200. At ISO s 100 and 6400, automatic white balance is still excellent at 0.2.

The Alpha 6400 starts up in 1.4 seconds. The camera records 11.1 JPEG frames per second until the card is full, and captures RAWs at the same speed for a total of 47 frames. The speed of burst shooting was the same in the Sony Alpha 6300, 11.1 frames per second in both JPEG and RAW, although fewer could be saved in a single burst.

Autofocus and shutter release in bright light and in low light when tested were measured at 0.5 of a second, of which the shutter lag was 0.03 of a second. One might ask why this is so different from the manufacturer’s claim[1] of 0.02 seconds for autofocus. The answer lies most likely in test protocols: Sony adds a footnote that specifies a number of conditions[2].

Video                                                                

Video resolution is measured by grabbing image frames from a video for analysis. Resolution measured from a video frame recorded at ISO 100 is 1209 LP/PH, 112 percent of the theoretical maximum. At ISO 1600, resolution is measured at 1158 LP/PH, 107 percent of the theoretical maximum.

Texture reproduction is good at low ISO , better than the Alpha 6300. In videos made with the Alpha 6400 at ISO 1600, texture reproduction is less good.

Sharpening is stronger in video made by the Alpha 6400 than in still images.

Visual noise would be noticeable in video images viewed at 100 percent at ISO 100 and obvious at ISO 1600. This represents a very slight improvement from the Alpha 6300, which produced visual noise scores in VN1 of 1.4 and 2.6, respectively.

Noise would not be visible in videos shot using the Alpha 6400 at ISO 100 when viewed either on a small mobile screen or as a large print (VN2 and VN3). Some noise would be visible in the ISO 1600 videos in both VN2 and VN3, albeit not enough to disturb the viewing of the image.

Dynamic range in video is 8.7 f-stops at ISO 100 and 8.0 f-stops at ISO 1600, similar to the Alpha 6300. Automatic white balance in video made by the Alpha 6400 is poorer than for still photography, but better than the Alpha 6300 in video mode.

[1] https://www.sony.com/electronics/interchangeable-lens-cameras/ilce-6400#product_details_default

[2] ‘Based on Sony research, measured using CIPA-compliant guidelines, and internal measurement method with an E 18-135 mm F3.5-5.6 OSS lens mounted, Pre-AF off and viewfinder in use.’

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