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Pentax K-3 versus Sony A7 II

The Pentax K-3 and the Sony Alpha A7 II are two enthusiast cameras that were revealed to the public, respectively, in October 2013 and November 2014. The K-3 is a DSLR, while the A7 II is a mirrorless interchangeable lens camera. The cameras are based on an APS-C (K-3) and a full frame sensor. The Pentax has a resolution of 24.1 megapixel, whereas the Sony provides 24 MP.

Body comparison

The physical size and weight of the Pentax K-3 and the Sony A7 II are illustrated in the side-by-side display below. 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. If you prefer, you can also use the toggle button to switch to a comparison in percentage terms (in this case, the camera on the left side – the K-3 – represents the basis for the calculations across all the size and weight measures).

Pentax K-3 vs Sony A7 II front
K-3 versus A7 II top view
K-3 and A7 II rear side
Body view (K-3 on the left)

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Sony A7 II is somewhat smaller (7 percent) than the Pentax K-3. Moreover, the A7 II is markedly lighter (25 percent) than the K-3. Cameras intended for semi-professional or professional use tend to be a bit bulkier in order to give them the necessary ruggedness. 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 comparisons there.

Camera Body Specifications
Camera Camera
Width
Camera
Height
Camera
Depth
Camera
Weight
Battery
Life
(CIPA)
Weather
Sealing
(y/n)
Camera
Launch
(year)
Launch
Price
(USD)
Street
Price
(amazon)
Used
Price
(ebay)
Pentax K-3 (⇒ rgt) 131 mm 100 mm 77 mm 800 g 560 YES 2013 1,299discont. check
Sony A7 II (⇒ lft) 127 mm 96 mm 60 mm 599 g 350 YES 2014 1,999 latest check
Canon 70D (⇒ lft | rgt) 139 mm 104 mm 79 mm 755 g 920 YES 2013 1,199discont. check
Nikon D7100 (⇒ lft | rgt) 136 mm 107 mm 76 mm 765 g 950 YES 2013 1,199discont. check
Olympus E-M1 (⇒ lft | rgt) 130 mm 94 mm 63 mm 497 g 350 YES 2013 1,399discont. check
Panasonic GX8 (⇒ lft | rgt) 133 mm 78 mm 63 mm 487 g 330 YES 2015 1,199 latest check
Pentax K-3 II (⇒ lft | rgt) 131 mm 100 mm 77 mm 800 g 720 YES 2015 1,099 latest check
Sony A9 (⇒ lft | rgt) 127 mm 96 mm 63 mm 673 g 650 YES 2017 4,499 latest check
Sony A6500 (⇒ lft | rgt) 120 mm 67 mm 53 mm 453 g 350 YES 2016 1,399 latest check
Sony A7R II (⇒ lft | rgt) 127 mm 96 mm 60 mm 625 g 290 YES 2015 3,199discont. check
Sony A7S II (⇒ lft | rgt) 127 mm 96 mm 60 mm 627 g 370 YES 2015 2,999 latest check
Sony A77 II (⇒ lft | rgt) 143 mm 104 mm 81 mm 647 g 480 YES 2014 1,199 latest check
Sony A7 (⇒ lft | rgt) 127 mm 94 mm 48 mm 474 g 340 YES 2013 1,699discont. check
Sony A7R (⇒ lft | rgt) 127 mm 94 mm 48 mm 465 g 340 YES 2013 2,299discont. check
Sony RX10 (⇒ lft | rgt) 129 mm 88 mm 102 mm 813 g 420 YES 2013 1,299discont. check
Sony A99 (⇒ lft | rgt) 147 mm 111 mm 78 mm 812 g 500 YES 2012 2,799discont. check

The listed prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The K-3 was launched at a markedly lower price (by 35 percent) than the A7 II, 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

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. 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 tend to be more expensive and lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Pentax K-3 features an APS-C sensor and the Sony A7 II a full frame sensor. The sensor area in the A7 II 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.

Pentax K-3 and Sony A7 II sensor measures
Sensor size

Despite having a smaller sensor, the Pentax K-3 offers a higher resolution of 24.1 megapixel, compared with 24 MP of the Sony A7 II. This megapixel advantage comes at the cost of a higher pixel density and a smaller size of the individual pixel (with a pixel pitch of 3.91μm versus 5.97μm for the A7 II). Moreover, it should be noted that the A7 II is a somewhat more recent model (by 1 year and 1 month) than the K-3, and its sensor might 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 the K-3 has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

K-3 versus A7 II MP
Sensor resolution

Since 2007, DXO Mark has published sensor performance measurements that have been derived using a consistent methodology. This service assesses and scores the color depth ("DXO Portrait"), dynamic range ("DXO Landscape"), and low-light sensitivity ("DXO Sports") of camera sensors, and also publishes an overall camera score. Of the two cameras under consideration, the A7 II has a markedly higher DXO score than the K-3 (overall score 10 points higher), which will translate into better image quality. The advantage is based on 1.2 bits higher color depth, 0.2 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.

Sensor Characteristics
Camera Sensor
Class
Resolution
(Megapixel)
Horiz.
Pixels
Vert.
Pixels
Video
Format
DXO
Portrait
DXO
Landscape
DXO
Sports
DXO
Overall
Pentax K-3 (⇒ rgt) APS-C 24.1 6016 4000 1080/60i 23.7 13.4 1216 80
Sony A7 II (⇒ lft) Full Frame 24.0 6000 4000 1080/60p 24.9 13.6 2449 90
Canon 70D (⇒ lft | rgt) APS-C 20.0 5472 3648 1080/30p 22.5 11.6 926 68
Nikon D7100 (⇒ lft | rgt) APS-C 24.0 6000 4000 1080/60p 24.2 13.7 1256 83
Olympus E-M1 (⇒ lft | rgt) Four Thirds 15.9 4608 3456 1080/30p 23.0 12.7 757 73
Panasonic GX8 (⇒ lft | rgt) Four Thirds 20.2 5184 3888 4K/30p 23.5 12.6 806 75
Pentax K-3 II (⇒ lft | rgt) APS-C 24.1 6016 4000 1080/60i 23.6 13.6 1106 80
Sony A9 (⇒ lft | rgt) Full Frame 24.0 6000 4000 4K/30p 24.9 13.3 3517 92
Sony A6500 (⇒ lft | rgt) APS-C 24.0 6000 4000 4K/30p 24.5 13.7 1405 85
Sony A7R II (⇒ lft | rgt) Full Frame 42.2 7952 5304 4K/30p 26.0 13.9 3434 98
Sony A7S II (⇒ lft | rgt) Full Frame 12.0 4240 2832 4K/30p 23.6 13.3 2993 85
Sony A77 II (⇒ lft | rgt) APS-C 24.0 6000 4000 1080/60p - - - -
Sony A7 (⇒ lft | rgt) Full Frame 24.0 6000 4000 1080/60p 24.8 14.2 2248 90
Sony A7R (⇒ lft | rgt) Full Frame 36.2 7360 4912 1080/60p 25.6 14.1 2746 95
Sony RX10 (⇒ lft | rgt) 1-inch 20.0 5472 3648 1080/60p 22.9 12.6 474 69
Sony A99 (⇒ lft | rgt) Full Frame 24.0 6000 4000 1080/60p 25.0 14.0 1555 89

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 A7 II provides a faster frame rate than the K-3. It can shoot movie footage at 1080/60p, while the Pentax is limited to 1080/60i.

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. For example, the A7 II has an electronic viewfinder (2400k dots), while the K-3 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 adjacent table lists some of the other core features of the Pentax K-3 and Sony A7 II along with similar information for a selection of comparators. The full specs-sheets can be found in the camera manual or, for example, in the dpreview camera hub.

Core Features
Camera Viewfinder
(Type or
'000 dots)
Control
Panel
(Y/n)
LCD
Size
(inch)
LCD
Resolution
('000 dots)
LCD
Attach-
ment
Touch
Screen
(Y/n)
Shutter
speed
(1/sec)
Shutter
flaps
(1/sec))
Build-in
Flash
(GN)
Build-in
Image
Stab
Pentax K-3 (⇒ rgt) optical YES 3.2 1037 fixed no 8000 8.3 13 YES
Sony A7 II (⇒ lft) 2400 no 3.0 1230 tilting no 8000 5.0 no YES
Canon 70D (⇒ lft | rgt) optical YES 3.0 1040 swivel YES 8000 7.0 12 no
Nikon D7100 (⇒ lft | rgt) optical YES 3.2 1229 fixed no 8000 6.0 12 no
Olympus E-M1 (⇒ lft | rgt) 2360 no 3.0 1037 tilting YES 8000 10.0 no YES
Panasonic GX8 (⇒ lft | rgt) 2360 no 3.0 1040 swivel YES 8000 10.0 no YES
Pentax K-3 II (⇒ lft | rgt) optical YES 3.2 1037 fixed no 8000 8.3 no YES
Sony A9 (⇒ lft | rgt) 3686 no 3.0 1440 tilting YES 8000 20.0 no YES
Sony A6500 (⇒ lft | rgt) 2300 no 3.0 922 tilting YES 4000 11.0 6 YES
Sony A7R II (⇒ lft | rgt) 2400 no 3.0 1229 tilting no 8000 5.0 no YES
Sony A7S II (⇒ lft | rgt) 2400 no 3.0 1229 tilting no 8000 5.0 no YES
Sony A77 II (⇒ lft | rgt) 2359 YES 3.0 1229 full-flex no 8000 12.0 12 YES
Sony A7 (⇒ lft | rgt) 2400 no 3.0 1230 tilting no 8000 5.0 no no
Sony A7R (⇒ lft | rgt) 2400 no 3.0 1230 tilting no 8000 4.0 no no
Sony RX10 (⇒ lft | rgt) 1440 YES 3.0 1229 tilting no 3200 10.0 10.2 no
Sony A99 (⇒ lft | rgt) 2359 YES 3.0 1229 full-flex no 8000 6.0 no YES

The A7 II is a current model that online retailers, such as amazon, will have in stock. In contrast, the K-3 has been discontinued (but it can be found pre-owned on ebay). As a replacement in the same line of cameras, the K-3 was succeeded by the Pentax K-3 II.

Summary

So what conclusions can be drawn? Is the Pentax K-3 better than the Sony A7 II or vice versa? A synthesis of the relative strong points of each of the models is listed below.


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Arguments in favor of the Pentax K-3:

  • Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
  • 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.
  • Faster burst: Shoots at higher frequency (8.3 vs 5 flaps/sec) to capture the decisive moment.
  • Longer lasting: Can take more shots (560 versus 350) on a single battery charge.
  • Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
  • More affordable: Was introduced into a lower priced category (35 percent cheaper at launch).
  • More heavily discounted: Has been on the market for longer (launched in October 2013).

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Advantages of the Sony Alpha A7 II:

  • 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).
  • Better low-light sensitivity: Can shoot in dim conditions (1 stops ISO advantage).
  • Better video: Provides higher movie framerates (1080/60i vs 1080/60p).
  • More framing info: Has an electronic viewfinder that displays shooting data.
  • 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 201g or 25 percent) and is thus easier to take along.
  • More legacy lens friendly: Can use many non-native lenses via adapters.
  • More modern: Was introduced somewhat (1 year and 1 month) more recently.

If the count of relative strengths (bullet points above) is taken as a measure, the A7 II emerges as the winner of the match-up (11 : 9 points). However, the pertinence of the various camera strengths will differ across photographers, so that you might want to weigh individual camera traits according to their importance for your own imaging needs.

K-3 09:11 A7 II

In any case, while the specs-based evaluation of cameras is instructive in revealing their potential as photographic tools, it remains incomplete and does no justice, for example, to the way the K-3 or the A7 II handle or 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 why expert reviews are important. The table below summarizes the assessments of some of the best known camera review sites. The full reviews are available, respectively, at cameralabs.com, dpreview.com, ephotozine.com, imaging-resource.com, and photographyblog.com.

Review scores
Camera camera
labs
dp
review
ephoto
zine
imaging
resource
photography
blog
Camera
Launch
(year)
Launch
Price
(USD)
Street
Price
(amazon)
Used
Price
(ebay)
Pentax K-3 (⇒ rgt) - 83/100 Gold 5/5 4.5/5 5/5 2013 1,299discont. check
Sony A7 II (⇒ lft) Rec 82/100 Silver 4.5/5 5/5 5/5 2014 1,999 latest check
Canon 70D (⇒ lft | rgt) HiRec 83/100 Gold 4.5/5 4.5/5 5/5 2013 1,199discont. check
Nikon D7100 (⇒ lft | rgt) HiRec 85/100 Gold 4.5/5 5/5 4.5/5 2013 1,199discont. check
Olympus E-M1 (⇒ lft | rgt) HiRec 84/100 Gold 4.5/5 4.5/5 4.5/5 2013 1,399discont. check
Panasonic GX8 (⇒ lft | rgt) Rec 82/100 Silver 4.5/5 5/5 4.5/5 2015 1,199 latest check
Pentax K-3 II (⇒ lft | rgt) - - 5/5 4.5/5 5/5 2015 1,099 latest check
Sony A9 (⇒ lft | rgt) .. 89/100 Gold 5/5 5/5 5/5 2017 4,499 latest check
Sony A6500 (⇒ lft | rgt) HiRec 85/100 Silver 4.5/5 5/5 4.5/5 2016 1,399 latest check
Sony A7R II (⇒ lft | rgt) HiRec 90/100 Gold 5/5 4.5/5 5/5 2015 3,199discont. check
Sony A7S II (⇒ lft | rgt) Rec - 4.5/5 5/5 5/5 2015 2,999 latest check
Sony A77 II (⇒ lft | rgt) - 80/100 Silver 4.5/5 4/5 5/5 2014 1,199 latest check
Sony A7 (⇒ lft | rgt) HiRec 80/100 Silver 5/5 4.5/5 5/5 2013 1,699discont. check
Sony A7R (⇒ lft | rgt) HiRec 82/100 Gold 4.5/5 5/5 5/5 2013 2,299discont. check
Sony RX10 (⇒ lft | rgt) Rec 80/100 Gold 4.5/5 4.5/5 4.5/5 2013 1,299discont. check
Sony A99 (⇒ lft | rgt) - 84/100 Gold 4.5/5 reviewed 4.5/5 2012 2,799discont. check

The review scores listed above should be treated with care, though. The assessments were made in relation to similar cameras of the same technological generation. Hence, a score should always be seen in the context of the camera's market launch date and its price, and comparing ratings of very distinct cameras or ones that are far apart in terms of their release date have little meaning. Also, kindly note that some of the listed sites have over time developped their review approaches and their reporting style.

Other comparisons

If you would like to see a different side-by-side camera review, just make a corresponding selection in the search boxes below. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored. If you cannot find the camera you are interested in, kindly get in touch, and I will try to locate and add the respective data to the application.

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