Pentax K-3 II versus Sony A7R III
The Pentax K-3 II and the Sony Alpha A7R III are two enthusiast cameras that were revealed to the public, respectively, in April 2015 and October 2017. The K-3 II is a DSLR, while the A7R III is a mirrorless interchangeable lens camera. The cameras are based on an APS-C (K-3 II) and a full frame (A7R III) sensor. The Pentax has a resolution of 24.1 megapixel, whereas the Sony provides 42.2 MP. Read on to find out how these two cameras compare with respect to their size, their sensors, their features, and their reception by expert reviewers.
Body comparison: Pentax K-3 II vs Sony A7R III
The physical size and weight of the Pentax K-3 II and the Sony A7R III are illustrated in the side-by-side display below. Three successive views from the front, the top, and the rear are shown. All width, height and depth measures are rounded to the nearest millimeter. You can also use the toggle button to switch to a percentage comparison if you prefer that the measures are being expressed in relative terms (in this case, the camera on the left – the K-3 II – represents 100 percent across all the size and weight measures).
If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Sony A7R III is notably smaller (7 percent) than the Pentax K-3 II. Moreover, the A7R III is markedly lighter (19 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 the specifications of available lenses in order to get the full picture of the size and weight of the two camera systems.
The table below summarizes the key physical specs of the two cameras alongside a broader set of comparators. If you want to switch the focus of the display and review another camera pair, just select a new right or left comparator from among the camera models in the table. Alternatively, you can also move across to the CAM-parator tool and choose from the broad selection of possible camera comparisons there.
|Camera Body Specifications|
|Pentax K-3 II»||5.2 in||3.9 in||3.0 in||28.2 oz||720||Y||Apr 2015||1,099|
|Sony A7R III«||5.0 in||3.8 in||2.9 in||22.9 oz||650||Y||Oct 2017||3,199|
|Canon 80D« »||5.5 in||4.1 in||3.1 in||25.8 oz||960||Y||Feb 2016||1,199|
|Nikon D7200« »||5.4 in||4.2 in||3.0 in||27.0 oz||1110||Y||Mar 2015||1,199||-|
|Olympus E-M1 II« »||5.3 in||3.6 in||2.6 in||20.2 oz||440||Y||Sep 2016||1,999|
|Olympus E-M5 II« »||4.9 in||3.3 in||1.8 in||16.5 oz||310||Y||Feb 2015||1,099|
|Panasonic GX8« »||5.2 in||3.1 in||2.5 in||17.2 oz||330||Y||Jul 2015||1,199||-|
|Pentax KP« »||5.2 in||4.0 in||3.0 in||24.8 oz||390||Y||Jan 2017||1,099|
|Pentax K-70« »||5.0 in||3.7 in||2.9 in||24.3 oz||410||Y||Jun 2016||649|
|Pentax K-3« »||5.2 in||3.9 in||3.0 in||28.2 oz||560||Y||Oct 2013||1,299||-|
|Pentax K-5« »||5.2 in||3.8 in||2.9 in||26.8 oz||740||Y||Sep 2010||1,099||-|
|Sony A7 III« »||5.0 in||3.8 in||2.9 in||22.9 oz||610||Y||Feb 2018||1,999|
|Sony A99 II« »||5.6 in||4.1 in||3.0 in||29.9 oz||490||Y||Sep 2016||3,199|
|Sony A7R II« »||5.0 in||3.8 in||2.4 in||22.0 oz||290||Y||Jun 2015||3,199||-|
|Sony RX10 II« »||5.1 in||3.5 in||4.0 in||28.7 oz||400||Y||Jun 2015||1,299||-|
|Sony A7 II« »||5.0 in||3.8 in||2.4 in||21.1 oz||350||Y||Nov 2014||1,999||-|
|Sony A7R« »||5.0 in||3.7 in||1.9 in||16.4 oz||340||Y||Oct 2013||2,299||-|
The price is, of course, an important factor in any camera decision. The listed launch prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The K-3 II was launched at a markedly lower price (by 66 percent) than the A7R III, 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.
Sensor comparison: Pentax K-3 II vs Sony A7R III
The size of the imaging sensor is a crucial determinant 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 A7R III a full frame sensor. The sensor area in the A7R III is 135 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.
With 42.2MP, the A7R III offers a higher resolution than the K-3 II (24.1MP), but the A7R III nevertheless has larger individual pixels (pixel pitch of 4.52μm versus 3.90μm for the K-3 II) due to its larger sensor. Moreover, the A7R III is a much more recent model (by 2 years and 6 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 its pixel-units. Coming back to sensor resolution, it should be mentioned that neither of the two cameras has an anti-alias filter installed, so they are able to capture all the detail the sensor resolves.
Both cameras have the capacity to capture high quality composite images by combining multiple shots after shifting the sensor by miniscule distances. This multi-shot, pixel-shift mode is most suitable for photography of stationary objects (landscapes, studio scenes).
Consistent information on actual sensor performance is available from DXO Mark for most cameras. 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 A7R III offers substantially better image quality than the K-3 II (overall score 20 points higher). The advantage is based on 2.4 bits higher color depth, 1.1 EV in additional dynamic range, and 1.7 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.
|Pentax K-3 II»||APS-C||24.1||6016||4000||1080/60i||23.6||13.6||1106||80|
|Sony A7R III«||Full Frame||42.2||7952||5304||4K/30p||26.0||14.7||3523||100|
|Canon 80D« »||APS-C||24.0||6000||4000||1080/60p||23.6||13.2||1135||79|
|Nikon D7200« »||APS-C||24.0||6000||4000||1080/60p||24.5||14.6||1333||87|
|Olympus E-M1 II« »||Four Thirds||20.2||5184||3888||4K/30p||23.7||12.8||1312||80|
|Olympus E-M5 II« »||Four Thirds||15.9||4608||3456||1080/60p||23.0||12.5||842||73|
|Panasonic GX8« »||Four Thirds||20.2||5184||3888||4K/30p||23.5||12.6||806||75|
|Pentax KP« »||APS-C||24.1||6016||4000||1080/60i||-||-||-||-|
|Pentax K-70« »||APS-C||24.0||6000||4000||1080/60i||-||-||-||-|
|Pentax K-3« »||APS-C||24.1||6016||4000||1080/60i||23.7||13.4||1216||80|
|Pentax K-5« »||APS-C||16.1||4928||3264||1080/25p||23.7||14.1||1162||82|
|Sony A7 III« »||Full Frame||24.0||6000||4000||4K/30p||25.0||14.7||3730||96|
|Sony A99 II« »||Full Frame||42.2||7952||5304||4K/30p||25.4||13.4||2317||92|
|Sony A7R II« »||Full Frame||42.2||7952||5304||4K/30p||26.0||13.9||3434||98|
|Sony RX10 II« »||1-inch||20.0||5472||3648||4K/30p||23.0||12.6||531||70|
|Sony A7 II« »||Full Frame||24.0||6000||4000||1080/60p||24.9||13.6||2449||90|
|Sony A7R« »||Full Frame||36.2||7360||4912||1080/60p||25.6||14.1||2746||95|
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 A7R III 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.
Feature comparison: Pentax K-3 II vs Sony A7R III
Apart from body and sensor, cameras can and do differ across a variety of features. For example, the A7R III has an electronic viewfinder (3686k 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 following table reports on some other key feature differences and similarities of the Pentax K-3 II, the Sony A7R III, and comparable cameras. If you need more detail on the specs, you can find comprehensive listings, for example, in the dpreview camera hub.
|Pentax K-3 II»||optical||Y||3.2||1037||fixed||n||8000||8.3||n||Y|
|Sony A7R III«||3686||n||3.0||1440||tilting||Y||8000||10.0||n||Y|
|Canon 80D« »||optical||Y||3.0||1040||swivel||Y||8000||7.0||Y||n|
|Nikon D7200« »||optical||Y||3.2||1229||fixed||n||8000||6.0||Y||n|
|Olympus E-M1 II« »||2360||n||3.0||1037||swivel||Y||8000||18.0||n||Y|
|Olympus E-M5 II« »||2360||n||3.0||1037||swivel||Y||8000||10.0||n||Y|
|Panasonic GX8« »||2360||n||3.0||1040||swivel||Y||8000||10.0||n||Y|
|Pentax KP« »||optical||n||3.0||921||tilting||n||6000||7.0||Y||Y|
|Pentax K-70« »||optical||n||3.0||921||swivel||n||6000||6.0||Y||Y|
|Pentax K-3« »||optical||Y||3.2||1037||fixed||n||8000||8.3||Y||Y|
|Pentax K-5« »||optical||Y||3.0||921||fixed||n||8000||7.0||Y||Y|
|Sony A7 III« »||2359||n||3.0||922||tilting||Y||8000||10.0||n||Y|
|Sony A99 II« »||2400||Y||3.0||1229||full-flex||n||8000||12.0||n||Y|
|Sony A7R II« »||2400||n||3.0||1229||tilting||n||8000||5.0||n||Y|
|Sony RX10 II« »||2359||Y||3.0||1229||tilting||n||3200||14.0||Y||Y|
|Sony A7 II« »||2400||n||3.0||1230||tilting||n||8000||5.0||n||Y|
|Sony A7R« »||2400||n||3.0||1230||tilting||n||8000||4.0||n||n|
Both the K-3 II and the A7R III are current models that good online retailers will have in stock. You can check the latest prices, for example, at amazon. The K-3 II replaced the earlier Pentax K-3, while the A7R III followed on from the Sony A7R II.
Review summary: Pentax K-3 II vs Sony A7R III
So what conclusions can be drawn? Is there a clear favorite between the Pentax K-3 II and the Sony A7R III? The listing below highlights the relative strengths of the two models.
Reasons to prefer the Pentax K-3 II:
- Brighter framing: Features an optical viewfinder for clear, lag-free composition.
- Easier setting verification: Has 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.
- Longer lasting: Can take more shots (720 versus 650) on a single battery charge.
- More affordable: Was introduced into a lower priced category (66 percent cheaper at launch).
- More heavily discounted: Has been available for much longer (launched in April 2015).
Arguments in favor of the Sony Alpha A7R III:
- More detail: Has more megapixels (42.2 vs 24.1MP), which boosts linear resolution by 32%.
- Better image quality: Scores substantially higher (20 points) in the DXO overall evaluation.
- Richer colors: Generates noticeably more natural colors (2.4 bits more color depth).
- More dynamic range: Captures a broader range of light and dark details (1.1 EV of extra DR).
- Better low-light sensitivity: Can shoot in dim conditions (1.7 stops ISO advantage).
- Better video: Provides higher definition movie capture (4K/30p vs 1080/60i).
- More framing info: Has an electronic viewfinder that displays shooting data.
- More detailed LCD: Has a higher resolution rear screen (1440k vs 1037k dots).
- 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.
- Faster burst: Shoots at higher frequency (10 vs 8.3 flaps/sec) to capture the decisive moment.
- Less heavy: Has a lower weight (by 150g or 19 percent) and is thus easier to take along.
- More legacy lens friendly: Can use many non-native lenses via adapters.
- More modern: Reflects 2 years and 6 months of technical progress since the K-3 II launch.
If the count of individual advantages (bullet points above) is taken as a guide, the A7R III is the clear winner of the contest (14 : 6 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.
In any case, while the comparison of the spec-sheets of cameras can offer a general idea of their imaging potential, it remains partial and cannot reveal, for example, the handling experience and imaging performance when actually working with the K-3 II or the A7R III. 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 why hands-on reviews by experts are important. The adjacent table relays the overall verdicts of several of the most popular camera review sites (cameralabs, dpreview, ephotozine, imaging-resource, photographyblog). The full reviews are available by clicking on the site logo in the table header.
|Pentax K-3 II»||-||-||5/5||4.5/5||5/5||Apr 2015||1,099|
|Sony A7R III«||HiRec||90/100||4.5/5||5/5||5/5||Oct 2017||3,199|
|Canon 80D« »||HiRec||84/100||4.5/5||4.5/5||4.5/5||Feb 2016||1,199|
|Nikon D7200« »||HiRec||84/100||4.5/5||4/5||4.5/5||Mar 2015||1,199||-|
|Olympus E-M1 II« »||HiRec||85/100||4.5/5||5/5||4.5/5||Sep 2016||1,999|
|Olympus E-M5 II« »||HiRec||81/100||5/5||4.5/5||5/5||Feb 2015||1,099|
|Panasonic GX8« »||Rec||82/100||4.5/5||5/5||4.5/5||Jul 2015||1,199||-|
|Pentax KP« »||-||82/100||5/5||-||4.5/5||Jan 2017||1,099|
|Pentax K-70« »||-||79/100||4.5/5||4/5||4.5/5||Jun 2016||649|
|Pentax K-3« »||-||83/100||5/5||4.5/5||5/5||Oct 2013||1,299||-|
|Pentax K-5« »||-||83/100||5/5||4.5/5||4.5/5||Sep 2010||1,099||-|
|Sony A7 III« »||HiRec||89/100||5/5||-||5/5||Feb 2018||1,999|
|Sony A99 II« »||-||85/100||4.5/5||4.5/5||4.5/5||Sep 2016||3,199|
|Sony A7R II« »||HiRec||90/100||5/5||4.5/5||5/5||Jun 2015||3,199||-|
|Sony RX10 II« »||HiRec||82/100||4.5/5||4.5/5||4/5||Jun 2015||1,299||-|
|Sony A7 II« »||Rec||82/100||4.5/5||5/5||5/5||Nov 2014||1,999||-|
|Sony A7R« »||HiRec||82/100||4.5/5||5/5||5/5||Oct 2013||2,299||-|
The above review scores should be interpreted with care, though. The assessments were made in relation to similar cameras of the same technological generation. 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.
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