Pentax K-3 II vs Sony A7
The Pentax K-3 II and the Sony Alpha A7 are two enthusiast cameras that were revealed to the public, respectively, in April 2015 and October 2013. The K-3 II is a DSLR, while the A7 is a mirrorless interchangeable lens camera. The cameras are based on an APS-C (K-3 II) and a full frame (A7) 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 A7? 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 A7. 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 size dimensions are rounded to the nearest millimeter.
The K-3 II can be obtained in two different colors (black, silver), while the A7 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 A7 is notably smaller (9 percent) than the Pentax K-3 II. Moreover, the A7 is substantially lighter (41 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 A7 can take 340 images on a single charge of its NP-FW50 power pack. The power pack in the A7 can be charged via the USB port, which can be very convenient when travelling.
The adjacent table lists the principal physical characteristics of the two cameras alongside a wider set of alternatives. If you would like to visualize and compare a different camera combination, you can navigate to the CAM-parator app and make your selection from a broad list of cameras there.
|1.||Pentax K-3 II||131 mm||100 mm||77 mm||800 g||720||Y||Apr 2015||1,099|
|2.||Sony A7||127 mm||94 mm||48 mm||474 g||340||Y||Oct 2013||1,699|
|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.||Pentax K-3 III||135 mm||104 mm||74 mm||820 g||800||Y||Mar 2021||1,999|
|6.||Pentax KP||132 mm||101 mm||76 mm||703 g||390||Y||Jan 2017||1,099|
|7.||Pentax K-70||126 mm||93 mm||74 mm||688 g||410||Y||Jun 2016||649|
|8.||Pentax K-S2||123 mm||91 mm||73 mm||678 g||410||Y||Feb 2015||749|
|9.||Pentax K-S1||121 mm||93 mm||70 mm||558 g||410||n||Aug 2014||749|
|10.||Pentax K-3||131 mm||100 mm||77 mm||800 g||560||Y||Oct 2013||1,299|
|11.||Pentax K-5 II||131 mm||97 mm||73 mm||760 g||740||Y||Sep 2012||1,099|
|12.||Pentax K-5||131 mm||97 mm||73 mm||760 g||740||Y||Sep 2010||1,099|
|13.||Sony A7 II||127 mm||96 mm||60 mm||599 g||350||Y||Nov 2014||1,999|
|14.||Sony A7S||127 mm||94 mm||48 mm||489 g||380||Y||Apr 2014||2,499|
|15.||Sony A7R||127 mm||94 mm||48 mm||465 g||340||Y||Oct 2013||2,299|
|16.||Sony RX1R||113 mm||65 mm||70 mm||482 g||270||n||Jun 2013||2,799|
|17.||Sony RX1||113 mm||65 mm||70 mm||482 g||270||n||Sep 2012||2,799|
|Notes: Measurements and pricing do not include easily detachable parts, such as add-on or interchangeable lenses or optional viewfinders.|
Any camera decision will obviously take relative prices into account. The manufacturer’s suggested retail prices give an idea on the placement of the camera in the maker’s lineup and the broader market. The K-3 II was launched at a markedly lower price (by 35 percent) than the A7, which puts it into a different market segment. Usually, retail prices stay at first close to the launch price, but after several months, discounts become available. 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. Then, after the new model is out, very good deals can frequently be found on the pre-owned market.
The size of the sensor inside a digital camera is one of the key determinants of image quality. All other things equal, a large sensor will have larger individual pixel-units that offer better low-light sensitivity, wider dynamic range, and richer color-depth than smaller pixels in a sensor of the same technological generation. Moreover, a large sensor camera will give the photographer more control over depth-of-field in the image and, thus, the ability to better isolate a subject from the background. On the downside, larger sensors tend to be more expensive and lead to bigger and heavier cameras and lenses.
Of the two cameras under consideration, the Pentax K-3 II features an APS-C sensor and the Sony A7 a full frame sensor. The sensor area in the A7 is 133 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.5 and 1.0. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.
In terms of underlying technology, both cameras are build around CMOS sensors.
Despite having a smaller sensor, the Pentax K-3 II offers a higher resolution of 24.1 megapixels, compared with 24 MP of the Sony A7. This megapixels advantage comes at the cost of a higher pixel density and a smaller size of the individual pixel (with a pixel pitch of 3.90μm versus 5.97μm for the A7). However, it should be noted that the K-3 II is a somewhat more recent model (by 1 year and 6 months) than the A7, and its sensor might have benefitted from technological advances during this time that partly offset its pixel-size disadvantage. 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 A7 has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.
Unlike the A7, 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 A7 are ISO 100 to ISO 25600, with the possibility to increase the ISO range to 50-51200.
For many cameras, data on sensor performance has been reported by DXO Mark. This service is based on lab testing and assigns an overall score to each camera sensor, as well as ratings for dynamic range ("DXO Landscape"), color depth ("DXO Portrait"), and low-light sensitivity ("DXO Sports"). Of the two cameras under consideration, the A7 has a markedly higher DXO score than the K-3 II (overall score 10 points higher), which will translate into better image quality. The advantage is based on 1.2 bits higher color depth, 0.6 EV in additional dynamic range, and 1 stops in additional low light sensitivity. 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|
|2.||Sony A7||Full Frame||24.0||6000||4000||1080/60p||24.8||14.2||2248||90|
|5.||Pentax K-3 III||APS-C||25.6||6192||4128||4K/30p||..||..||..||..|
|11.||Pentax K-5 II||APS-C||16.1||4928||3264||1080/25p||23.8||14.1||1235||82|
|13.||Sony A7 II||Full Frame||24.0||6000||4000||1080/60p||24.9||13.6||2449||90|
|14.||Sony A7S||Full Frame||12.0||4240||2832||1080/60p||23.9||13.2||3702||87|
|15.||Sony A7R||Full Frame||36.2||7360||4912||1080/60p||25.6||14.1||2746||95|
|16.||Sony RX1R||Full Frame||24.0||6000||4000||1080/60p||25.0||13.6||2537||91|
|17.||Sony RX1||Full Frame||24.0||6000||4000||1080/60p||25.1||14.3||2534||93|
Many modern cameras are not only capable of taking still images, but can also record movies. Both cameras under consideration are equipped with sensors that have a sufficiently high read-out speed for moving images, but the A7 provides a faster frame rate than the K-3 II. It can shoot movie footage at 1080/60p, while the Pentax is limited to 1080/60i.
Apart from body and sensor, cameras can and do differ across a variety of features. For example, the A7 has an electronic viewfinder (2400k 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 A7 has a higher magnification than the one of the K-3 II (0.71x vs 0.63x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The table below summarizes some of the other core capabilities of the Pentax K-3 II and Sony A7 in connection with corresponding information for a sample of similar cameras.
|1.||Pentax K-3 II||optical||Y||3.2||1037||fixed||n||1/8000s||8.3||n||Y|
|5.||Pentax K-3 III||optical||Y||3.2||1620||fixed||Y||1/8000s||12.0||n||Y|
|11.||Pentax K-5 II||optical||Y||3.0||921||fixed||n||1/8000s||7.0||Y||Y|
|13.||Sony A7 II||2400||n||3.0||1230||tilting||n||1/8000s||5.0||n||Y|
One feature that is present on the K-3 II, but is missing on the A7 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 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 A7 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 A7 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 A7 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||-||-||-|
|5.||Pentax K-3 III||Y||stereo||mono||Y||Y||micro||3.2||Y||-||Y|
|11.||Pentax K-5 II||Y||stereo||mono||Y||-||mini||2.0||-||-||-|
|13.||Sony A7 II||Y||stereo||mono||Y||Y||micro||2.0||Y||Y||-|
It is notable that the A7 offers wifi support, which can be a very convenient means to transfer image data to an off-camera location. In contrast, the K-3 II does not provide wifi capability.
Studio photographers will appreciate that the Pentax K-3 II (unlike the A7) 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.
Both the K-3 II and the A7 have been discontinued, but can regularly be found used on eBay. The A7 was replaced by the Sony A7 II, while the K-3 II was followed 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 conclusions can be drawn? Which of the two cameras – the Pentax K-3 II or the Sony A7 – has the upper hand? Is one clearly better than the other? Below is a summary of the relative strengths of each of the two contestants.
Advantages 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.
- 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.
- Faster burst: Shoots at higher frequency (8.3 vs 5 flaps/sec) to capture the decisive moment.
- Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
- Longer lasting: Can take more shots (720 versus 340) 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 affordable: Was introduced into a lower priced category (35 percent cheaper at launch).
- More modern: Is somewhat more recent (announced 1 year and 6 months after the A7).
Reasons to prefer the Sony Alpha A7:
- Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
- Better image quality: Scores markedly higher (10 points) in the DXO overall evaluation.
- Richer colors: Generates noticeably more natural colors (1.2 bits more color depth).
- More dynamic range: Captures a broader range of light and dark details (0.6 EV of extra DR).
- Better low-light sensitivity: Can shoot in dim conditions (1 stops ISO advantage).
- Better video: Provides higher movie framerates (1080/60p versus 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 (0.71x vs 0.63x).
- More detailed LCD: Has a higher resolution rear screen (1230k vs 1037k dots).
- More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
- Less heavy: Has a lower weight (by 326g or 41 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 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.
- More heavily discounted: Has been on the market for longer (launched in October 2013).
If the count of relative strengths (bullet points above) is taken as a measure, the A7 emerges as the winner of the match-up (17 : 15 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 wedding photographer will view the differences between cameras in a way that diverges from the perspective of a travel photog, and a person interested in cityscapes has distinct needs from a macro 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 A7 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 remains incomplete and does no justice, for example, to the way the K-3 II or the A7 perform in practice. At times, user reviews, such as those published at amazon, address these issues in a useful manner, but such feedback is on many occasions incomplete, inconsistent, and unreliable.
This is where reviews by experts come in. The table below provides a synthesis of the camera assessments of some of the best known photo-gear 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 A7||5/5||+ +||80/100||5/5||5/5||Oct 2013||1,699|
|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.||Pentax K-3 III||..||..||..||..||..||Mar 2021||1,999|
|6.||Pentax KP||4/5||..||82/100||5/5||4.5/5||Jan 2017||1,099|
|7.||Pentax K-70||4.5/5||..||79/100||4.5/5||4.5/5||Jun 2016||649|
|8.||Pentax K-S2||4.5/5||..||..||5/5||4.5/5||Feb 2015||749|
|9.||Pentax K-S1||4/5||..||..||4.5/5||4/5||Aug 2014||749|
|10.||Pentax K-3||4/5||..||83/100||5/5||5/5||Oct 2013||1,299|
|11.||Pentax K-5 II||5/5||..||80/100||5/5||4.5/5||Sep 2012||1,099|
|12.||Pentax K-5||4/5||..||83/100||5/5||4.5/5||Sep 2010||1,099|
|13.||Sony A7 II||5/5||+||82/100||4.5/5||5/5||Nov 2014||1,999|
|14.||Sony A7S||4/5||..||86/100||4.5/5||5/5||Apr 2014||2,499|
|15.||Sony A7R||5/5||+ +||82/100||4.5/5||5/5||Oct 2013||2,299|
|16.||Sony RX1R||5/5||..||..||4/5||4.5/5||Jun 2013||2,799|
|17.||Sony RX1||5/5||..||79/100||4/5||4.5/5||Sep 2012||2,799|
|Notes: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.|
The review scores listed above should be treated with care, though. The ratings were established in reference to similarly priced cameras that were available in the market at the time of the review. Hence, a score should always be seen in the context of the camera's market launch date and its price, 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 use the search menu below. As an alternative, you can also directly jump to any one of the listed comparisons that were previously generated by the CAM-parator tool.
Specifications: Pentax K-3 II vs Sony A7
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 A7|
|Camera Type||Digital single lens reflex||Mirrorless system camera|
|Camera Lens||Pentax K mount lenses||Sony E mount lenses|
|Launch Date||April 2015||October 2013|
|Launch Price||USD 1,099||USD 1,699|
|Sensor Specs||Pentax K-3 II||Sony A7|
|Sensor Format||APS-C Sensor||Full Frame Sensor|
|Sensor Size||23.5 x 15.6 mm||35.8 x 23.9 mm|
|Sensor Area||366.6 mm2||855.62 mm2|
|Sensor Diagonal||28.2 mm||43 mm|
|Sensor Resolution||24.1 Megapixels||24 Megapixels|
|Image Resolution||6016 x 4000 pixels||6000 x 4000 pixels|
|Pixel Pitch||3.90 μm||5.97 μm|
|Pixel Density||6.56 MP/cm2||2.80 MP/cm2|
|Moiré control||no AA filter||Anti-Alias filter|
|Movie Capability||1080/60i Video||1080/60p Video|
|ISO Setting||100 - 51,200 ISO||100 - 25,600 ISO|
|ISO Boost||no Enhancement||50 - 51,200 ISO|
|Image Processor||PRIME III||BIONZ X|
|DXO Sensor Quality (score)||80||90|
|DXO Color Depth (bits)||23.6||24.8|
|DXO Dynamic Range (EV)||13.6||14.2|
|DXO Low Light (ISO)||1106||2248|
|Screen Specs||Pentax K-3 II||Sony A7|
|Viewfinder Type||Optical viewfinder||Electronic viewfinder|
|Viewfinder Field of View||100%||100%|
|Viewfinder Resolution||2400k 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||1230k dots|
|LCD Attachment||Fixed screen||Tilting screen|
|Shooting Specs||Pentax K-3 II||Sony A7|
|Focus System||Phase-detect AF||On-Sensor Phase-detect|
|Manual Focusing Aid||Focus Peaking||Focus Peaking|
|Max Shutter Speed (mechanical)||1/8000s||1/8000s|
|Continuous Shooting||8.3 shutter flaps/s||5 shutter flaps/s|
|Time-Lapse Photography||Intervalometer built-in||no Intervalometer|
|Image Stabilization||In-body stabilization||Lens stabilization only|
|Fill Flash||no On-Board Flash||no On-Board 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 A7|
|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||Headphone port|
|Wifi Support||no Wifi||Wifi built-in|
|Near-Field Communication||no NFC||NFC built-in|
|Geotagging||GPS built-in||no internal GPS|
|Body Specs||Pentax K-3 II||Sony A7|
|Environmental Sealing||Weathersealed body||Weathersealed body|
|Battery Life (CIPA)||720 shots per charge||340 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)
127 x 94 x 48 mm
(5.0 x 3.7 x 1.9 in)
|Camera Weight||800 g (28.2 oz)||474 g (16.7 oz)|
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