Pentax K-3 II vs Sony A6400
The Pentax K-3 II and the Sony Alpha A6400 are two enthusiast cameras that were announced, respectively, in April 2015 and January 2019. The K-3 II is a DSLR, while the A6400 is a mirrorless interchangeable lens camera. Both cameras are equipped with an APS-C sensor. The Pentax has a resolution of 24.1 megapixels, whereas the Sony provides 24 MP.
Below is an overview of the main specs of the two cameras as a starting point for the comparison.
Going beyond this snapshot of core features and characteristics, what are the differences between the Pentax K-3 II and the Sony Alpha A6400? Which one should you buy? Read on to find out how these two cameras compare with respect to their body size, their imaging sensors, their shooting features, their input-output connections, and their reception by expert reviewers.
The side-by-side display below illustrates the physical size and weight of the Pentax K-3 II and the Sony A6400. The two cameras are presented according to their relative size. Three consecutive views from the front, the top, and the rear side are shown. All width, height and depth dimensions are rounded to the nearest millimeter.
The K-3 II can be obtained in two different colors (black, silver), while the A6400 is only available in black.
If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Sony A6400 is considerably smaller (39 percent) than the Pentax K-3 II. Moreover, the A6400 is substantially lighter (50 percent) than the K-3 II. In this context, it is worth noting that both cameras are splash and dust-proof and can, hence, be used in inclement weather conditions or harsh environments.
The above size and weight comparisons are to some extent incomplete since they do not consider the interchangeable lenses that both of these cameras require. Hence, you might want to study and compare the specifications of available lenses in order to get the full picture of the size and weight of the two camera systems.
Concerning battery life, the K-3 II gets 720 shots out of its D-LI90 battery, while the A6400 can take 410 images on a single charge of its NP-FW50 power pack. The power pack in the A6400 can be charged via the USB port, which can be very convenient when travelling.
The following table provides a synthesis of the main physical specifications of the two cameras and other similar ones. If you want to switch the focus of the display and review another camera pair, you can move across to the CAM-parator tool and choose from the broad selection of possible camera comparisons there.
|1.||Pentax K-3 II||131 mm||100 mm||77 mm||800 g||720||Y||Apr 2015||1,099|
|2.||Sony A6400||120 mm||67 mm||50 mm||403 g||410||Y||Jan 2019||899|
|3.||Canon 80D||139 mm||105 mm||79 mm||730 g||960||Y||Feb 2016||1,199|
|4.||Nikon D7200||136 mm||107 mm||76 mm||765 g||1110||Y||Mar 2015||1,199|
|5.||Nikon D5300||125 mm||98 mm||76 mm||480 g||600||n||Oct 2013||799|
|6.||Pentax K-3 III||135 mm||104 mm||74 mm||820 g||800||Y||Mar 2021||1,999|
|7.||Pentax KP||132 mm||101 mm||76 mm||703 g||390||Y||Jan 2017||1,099|
|8.||Pentax K-70||126 mm||93 mm||74 mm||688 g||410||Y||Jun 2016||649|
|9.||Pentax K-S2||123 mm||91 mm||73 mm||678 g||410||Y||Feb 2015||749|
|10.||Pentax K-S1||121 mm||93 mm||70 mm||558 g||410||n||Aug 2014||749|
|11.||Pentax K-3||131 mm||100 mm||77 mm||800 g||560||Y||Oct 2013||1,299|
|12.||Pentax K-5 II||131 mm||97 mm||73 mm||760 g||740||Y||Sep 2012||1,099|
|13.||Pentax K-5||131 mm||97 mm||73 mm||760 g||740||Y||Sep 2010||1,099|
|14.||Sony A6100||120 mm||67 mm||59 mm||396 g||420||n||Aug 2019||749|
|15.||Sony A6300||120 mm||67 mm||49 mm||404 g||400||Y||Feb 2016||999|
|16.||Sony A5100||110 mm||63 mm||36 mm||283 g||400||n||Aug 2014||549|
|17.||Sony A6000||120 mm||67 mm||45 mm||344 g||360||n||Feb 2014||599|
|Notes: Measurements and pricing do not include easily detachable parts, such as add-on or interchangeable lenses or optional viewfinders.|
Any camera decision will naturally be influenced heavily by the price. The retail prices at the time of the camera’s release place the model in the market relative to other models in the producer’s line-up and the competition. The A6400 was launched at a somewhat lower price (by 18 percent) than the K-3 II, which makes it more attractive for photographers on a tight budget. Normally, street prices remain initially close to the MSRP, but after a couple of months, the first discounts appear. Later in the product cycle and, in particular, when the replacement model is about to appear, further discounting and stock clearance sales often push the camera price considerably down.
The imaging sensor is at the core of digital cameras and its size is one of the main determining factors of image quality. A large sensor will generally have larger individual pixels that offer better low-light sensitivity, provide wider dynamic range, and have richer color-depth than smaller pixels in a sensor of the same technological generation. Further, a large sensor camera will give the photographer additional creative options when using shallow depth-of-field to isolate a subject from its background. On the downside, larger sensors are more costly to manufacture and tend to lead to bigger and heavier cameras and lenses.
Both cameras under consideration feature an APS-C sensor and have a format factor (sometimes also referred to as "crop factor") of 1.5. Within the spectrum of camera sensors, this places the review cameras among the medium-sized sensor cameras that aim to strike a balance between image quality and portability. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.
While the two cameras under review share the same sensor size, the K-3 II offers a slightly higher resolution of 24.1 megapixels, compared with 24 MP of the A6400. This megapixels advantage translates into a 0.3 percent gain in linear resolution. On the other hand, these sensor specs imply that the K-3 II has a higher pixel density and a smaller size of the individual pixel (with a pixel pitch of 3.90μm versus 3.91μm for the A6400). Moreover, it should be noted that the A6400 is much more recent (by 3 years and 8 months) than the K-3 II, and its sensor will have benefitted from technological advances during this time that further enhance the light gathering capacity of individual pixels. Coming back to sensor resolution, it should be mentioned that the K-3 II has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.
The A6400 has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.
Unlike the A6400, the K-3 II has the capacity to capture high quality composite images by combining multiple shots after shifting its sensor by miniscule distances. This multi-shot, pixel-shift mode is most suitable for photography of stationary objects (landscapes, studio scenes).
The Pentax K-3 II has a native sensitivity range from ISO 100 to ISO 51200. The corresponding ISO settings for the Sony Alpha A6400 are ISO 100 to ISO 32000, with the possibility to increase the ISO range to 100-102400.
For many cameras, data on sensor performance has been reported by DXO Mark. This service determines an overall sensor rating, as well as sub-scores for low-light sensitivity ("DXO Sports"), dynamic range ("DXO Landscape"), and color depth ("DXO Portrait"). The Overall DXO ratings for the two cameras under consideration are close, suggesting that they provide similar imaging performance. The following table provides an overview of the physical sensor characteristics, as well as the sensor quality measurements for a selection of comparators.
| DXO |
|1.||Pentax K-3 II||APS-C||24.1||6016||4000||1080/60i||23.6||13.6||1106||80|
|6.||Pentax K-3 III||APS-C||25.6||6192||4128||4K/30p||..||..||..||..|
|12.||Pentax K-5 II||APS-C||16.1||4928||3264||1080/25p||23.8||14.1||1235||82|
Many modern cameras are not only capable of taking still images, but also of capturing video footage. The two cameras under consideration both have sensors whose read-out speed is fast enough to capture moving pictures, but the A6400 provides a better video resolution than the K-3 II. It can shoot movie footage at 4K/30p, while the Pentax is limited to 1080/60i.
Apart from body and sensor, cameras can and do differ across a range of features. For example, the A6400 has an electronic viewfinder (2359k dots), while the K-3 II has an optical one. Both systems have their advantages, with the electronic viewfinder making it possible to project supplementary shooting information into the framing view, whereas the optical viewfinder offers lag-free viewing and a very clear framing image. The viewfinders of both cameras offer the same field of view (100%), but the viewfinder of the A6400 has a higher magnification than the one of the K-3 II (0.70x vs 0.63x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The adjacent table lists some of the other core features of the Pentax K-3 II and Sony A6400 along with similar information for a selection of comparators.
|1.||Pentax K-3 II||optical||Y||3.2||1037||fixed||n||1/8000s||8.3||n||Y|
|6.||Pentax K-3 III||optical||Y||3.2||1620||fixed||Y||1/8000s||12.0||n||Y|
|12.||Pentax K-5 II||optical||Y||3.0||921||fixed||n||1/8000s||7.0||Y||Y|
One feature that is present on the K-3 II, but is missing on the A6400 is a top-level LCD. While being, of course, smaller than the rear screen, the control panel conveys some of the essential shooting information and can be convenient for quick and easy settings verification.The A6400 has an articulated screen that can be turned to be front-facing. This characteristic will be appreciated by vloggers and photographers who are interested in taking selfies. In contrast, the K-3 II does not have a selfie-screen.
The reported shutter speed information refers to the use of the mechanical shutter. Yet, some cameras only have an electronic shutter, while others have an electronic shutter in addition to a mechanical one. In fact, the A6400 is one of those camera that have an additional electronic shutter, which makes completely silent shooting possible. However, this mode is less suitable for photographing moving objects (risk of rolling shutter) or shooting under artificial light sources (risk of flickering).
The Pentax K-3 II has an intervalometer built-in. This enables the photographer to capture time lapse sequences, such as flower blooming, a sunset or moon rise, without purchasing an external camera trigger and related software.
The K-3 II writes its imaging data to SDXC cards, while the A6400 uses SDXC or Memory Stick PRO Duo cards. The K-3 II features dual card slots, which can be very useful in case a memory card fails. In contrast, the A6400 only has one slot. Both cameras can use UHS-I cards, which provide for Ultra High Speed data transfer of up to 104 MB/s.
For some imaging applications, the extent to which a camera can communicate with its environment can be an important aspect in the camera decision process. The table below provides an overview of the connectivity of the Pentax K-3 II and Sony Alpha A6400 and, in particular, the interfaces the cameras (and selected comparators) provide for accessory control and data transfer.
| WiFi |
| NFC |
|1.||Pentax K-3 II||Y||mono||mono||Y||Y||mini||3.0||-||-||-|
|6.||Pentax K-3 III||Y||stereo||mono||Y||Y||micro||3.2||Y||-||Y|
|12.||Pentax K-5 II||Y||stereo||mono||Y||-||mini||2.0||-||-||-|
It is notable that the K-3 II has a headphone jack, which is not present on the A6400 This port makes it possible to attach external headphones and monitor the quality of sound during the recording process.
Studio photographers will appreciate that the Pentax K-3 II (unlike the A6400) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.
Travel and landscape photographers will find it useful that the K-3 II has an internal geolocalization sensor and can record GPS coordinates in its EXIF data.
The A6400 is a recent model that features in the current product line-up of Sony. In contrast, the K-3 II has been discontinued (but can be found pre-owned on eBay). As a replacement in the same line of cameras, the K-3 II was succeeded by the Pentax K-3 III. Further information on the two cameras (e.g. user guides, manuals), as well as related accessories, can be found on the official Pentax and Sony websites.
So what is the bottom line? Which of the two cameras – the Pentax K-3 II or the Sony A6400 – has the upper hand? Is one clearly better than the other? The listing below highlights the relative strengths of the two models.
Arguments in favor of the Pentax K-3 II:
- Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
- High quality composites: Can combine several shots after pixel-shifting its sensor.
- Better sound control: Has a headphone port that enables audio monitoring while recording.
- Brighter framing: Features an optical viewfinder for clear, lag-free composition.
- Easier setting verification: Features an LCD display on top to control shooting parameters.
- Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
- More detailed LCD: Has a higher resolution rear screen (1037k vs 922k dots).
- Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
- Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
- Longer lasting: Can take more shots (720 versus 410) on a single battery charge.
- Sharper images: Has hand-shake reducing image stabilization built-in.
- Easier geotagging: Features an internal GPS sensor to log localization data.
- Faster data transfer: Supports a more advanced USB protocol (3.0 vs 2.0).
- Better studio light control: Has a PC Sync socket to connect to professional strobe lights.
- Greater peace of mind: Features a second card slot as a backup in case of memory card failure.
- More heavily discounted: Has been available for much longer (launched in April 2015).
Advantages of the Sony Alpha A6400:
- Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
- Better low-light sensitivity: Can shoot in dim conditions (0.4 stops ISO advantage).
- Better video: Provides higher definition movie capture (4K/30p vs 1080/60i).
- Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
- More framing info: Has an electronic viewfinder that displays shooting data.
- Larger viewfinder image: Features a viewfinder with a higher magnification (0.70x vs 0.63x).
- More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
- Fewer buttons to press: Has a touchscreen to facilitate handling and shooting adjustments.
- More selfie-friendly: Has an articulated screen that can be turned to be front-facing.
- Faster burst: Shoots at higher frequency (11 vs 8.3 flaps/sec) to capture the decisive moment.
- Less disturbing: Has an electronic shutter option for completely silent shooting.
- More compact: Is smaller (120x67mm vs 131x100mm) and will fit more readily into a bag.
- Less heavy: Has a lower weight (by 397g or 50 percent) and is thus easier to take along.
- Easier travel charging: Can be conveniently charged via its USB port.
- More legacy lens friendly: Can use many non-native lenses via adapters.
- Easier fill-in: Has a small integrated flash to brighten shadows of backlit subjects.
- Easier file upload: Has wifi built in for automatic backup or image transfer to the web.
- Easier device pairing: Supports NFC for fast wireless image transfer over short distances.
- Easier wireless transfer: Supports Bluetooth for image sharing without cables.
- More affordable: Was released into a lower priced segment (18 percent cheaper at launch).
- More modern: Reflects 3 years and 8 months of technical progress since the K-3 II launch.
If the number of relative strengths (bullet points above) is taken as a guide, the A6400 is the clear winner of the contest (21 : 16 points). However, the relevance of individual strengths will vary across photographers, so that you might want to apply your own weighing scheme to the summary points when reflecting and deciding on a new camera. A professional wildlife photographer will view the differences between cameras in a way that diverges from the perspective of a family photog, and a person interested in architecture has distinct needs from a sports shooter. Hence, the decision which camera is best and worth buying is often a very personal one.
How about other alternatives? Do the specifications of the Pentax K-3 II and the Sony A6400 place the cameras among the top in their class? Find out in the latest Best DSLR Camera and Best Mirrorless Interchangeable Lens Camera listings whether the two cameras rank among the cream of the crop.
In any case, while the specs-based evaluation of cameras can be instructive in revealing their potential as photographic tools, it says little about, for example, the shooting experience and imaging performance of the K-3 II and the A6400 in practical situations. User reviews that are available, for instance, at amazon can sometimes shed light on these issues, but such feedback is all too often partial, inconsistent, and inaccurate.
This is where reviews by experts come in. The following table reports the overall ratings of the cameras as published by some of the major camera review sites (amateurphotographer [AP], cameralabs [CL], dpreview [DPR], ephotozine [EPZ], photographyblog [PB]). As can be seen, the professional reviewers agree in many cases on the quality of different cameras, but sometimes their assessments diverge, reinforcing the earlier point that a camera decision is often a very personal choice.
|1.||Pentax K-3 II||4.5/5||..||..||5/5||5/5||Apr 2015||1,099|
|2.||Sony A6400||4/5||+||85/100||4.5/5||4/5||Jan 2019||899|
|3.||Canon 80D||4/5||+ +||84/100||4.5/5||4.5/5||Feb 2016||1,199|
|4.||Nikon D7200||4/5||+ +||84/100||4.5/5||4.5/5||Mar 2015||1,199|
|5.||Nikon D5300||4/5||+ +||79/100||4.5/5||4.5/5||Oct 2013||799|
|6.||Pentax K-3 III||..||..||..||..||..||Mar 2021||1,999|
|7.||Pentax KP||4/5||..||82/100||5/5||4.5/5||Jan 2017||1,099|
|8.||Pentax K-70||4.5/5||..||79/100||4.5/5||4.5/5||Jun 2016||649|
|9.||Pentax K-S2||4.5/5||..||..||5/5||4.5/5||Feb 2015||749|
|10.||Pentax K-S1||4/5||..||..||4.5/5||4/5||Aug 2014||749|
|11.||Pentax K-3||4/5||..||83/100||5/5||5/5||Oct 2013||1,299|
|12.||Pentax K-5 II||5/5||..||80/100||5/5||4.5/5||Sep 2012||1,099|
|13.||Pentax K-5||4/5||..||83/100||5/5||4.5/5||Sep 2010||1,099|
|14.||Sony A6100||..||..||82/100||4/5||5/5||Aug 2019||749|
|15.||Sony A6300||4.5/5||+||85/100||5/5||5/5||Feb 2016||999|
|16.||Sony A5100||4.5/5||+||..||4.5/5||5/5||Aug 2014||549|
|17.||Sony A6000||5/5||+||80/100||4.5/5||5/5||Feb 2014||599|
|Notes: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.|
Care should be taken when interpreting the review scores above, though. The ratings are only valid when referring to cameras in the same category and of the same age. Thus, a score needs to be put into the context of the launch date and the launch price of the camera, and comparisons of ratings among very different cameras or across long time periods have little meaning. Also, kindly note that some of the listed sites have over time developped their review approaches and their reporting style.
Other camera comparisons
Did this review help to inform your camera decision process? In case you would like to check on the differences and similarities of other camera models, just make your choice using the following search menu. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored.
Specifications: Pentax K-3 II vs Sony A6400
Below is a side-by-side comparison of the specs of the two cameras to facilitate a quick review of their differences and common features.
|Camera Model||Pentax K-3 II||Sony A6400|
|Camera Type||Digital single lens reflex||Mirrorless system camera|
|Camera Lens||Pentax K mount lenses||Sony E mount lenses|
|Launch Date||April 2015||January 2019|
|Launch Price||USD 1,099||USD 899|
|Sensor Specs||Pentax K-3 II||Sony A6400|
|Sensor Format||APS-C Sensor||APS-C Sensor|
|Sensor Size||23.5 x 15.6 mm||23.5 x 15.6 mm|
|Sensor Area||366.6 mm2||366.6 mm2|
|Sensor Diagonal||28.2 mm||28.2 mm|
|Sensor Resolution||24.1 Megapixels||24 Megapixels|
|Image Resolution||6016 x 4000 pixels||6000 x 4000 pixels|
|Pixel Pitch||3.90 μm||3.91 μm|
|Pixel Density||6.56 MP/cm2||6.55 MP/cm2|
|Moiré control||no AA filter||Anti-Alias filter|
|Movie Capability||1080/60i Video||4K/30p Video|
|ISO Setting||100 - 51,200 ISO||100 - 32,000 ISO|
|ISO Boost||no Enhancement||100 - 102,400 ISO|
|Image Processor||PRIME III||BIONZ X|
|DXO Sensor Quality (score)||80||83|
|DXO Color Depth (bits)||23.6||24|
|DXO Dynamic Range (EV)||13.6||13.6|
|DXO Low Light (ISO)||1106||1431|
|Screen Specs||Pentax K-3 II||Sony A6400|
|Viewfinder Type||Optical viewfinder||Electronic viewfinder|
|Viewfinder Field of View||100%||100%|
|Viewfinder Resolution||2359k dots|
|Top-Level Screen||Control Panel||no Top Display|
|LCD Framing||Live View||Live View|
|Rear LCD Size||3.2inch||3.0inch|
|LCD Resolution||1037k dots||922k dots|
|LCD Attachment||Fixed screen||Tilting screen|
|Touch Input||no Touchscreen||Touchscreen|
|Shooting Specs||Pentax K-3 II||Sony A6400|
|Focus System||Phase-detect AF||On-Sensor Phase-detect|
|Manual Focusing Aid||Focus Peaking||Focus Peaking|
|Max Shutter Speed (mechanical)||1/8000s||1/4000s|
|Continuous Shooting||8.3 shutter flaps/s||11 shutter flaps/s|
|Shutter Life Expectancy||200 000 actuations||200 000 actuations|
|Electronic Shutter||no E-Shutter||YES|
|Time-Lapse Photography||Intervalometer built-in||no Intervalometer|
|Image Stabilization||In-body stabilization||Lens stabilization only|
|Fill Flash||no On-Board Flash||Build-in Flash|
|Storage Medium||SDXC cards||MS or SDXC cards|
|Second Storage Option||Dual card slots||Single card slot|
|UHS card support||UHS-I||UHS-I|
|Connectivity Specs||Pentax K-3 II||Sony A6400|
|Studio Flash||PC Sync socket||no PC Sync|
|USB Connector||USB 3.0||USB 2.0|
|HDMI Port||mini HDMI||micro HDMI|
|Microphone Port||External MIC port||External MIC port|
|Headphone Socket||Headphone port||no Headphone port|
|Wifi Support||no Wifi||Wifi built-in|
|Near-Field Communication||no NFC||NFC built-in|
|Bluetooth Support||no Bluetooth||Bluetooth built-in|
|Geotagging||GPS built-in||no internal GPS|
|Body Specs||Pentax K-3 II||Sony A6400|
|Environmental Sealing||Weathersealed body||Weathersealed body|
|Battery Life (CIPA)||720 shots per charge||410 shots per charge|
|In-Camera Charging||no USB charging||USB charging|
131 x 100 x 77 mm
(5.2 x 3.9 x 3.0 in)
120 x 67 x 50 mm
(4.7 x 2.6 x 2.0 in)
|Camera Weight||800 g (28.2 oz)||403 g (14.2 oz)|
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