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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 officially introduced, 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 (A7 II) sensor. The Pentax has a resolution of 24.1 megapixel, whereas the Sony provides 24 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 vs Sony A7 II

The side-by-side display below illustrates the physical size and weight of the Pentax K-3 and the Sony A7 II. Three consecutive views from the front, the top, and the rear side 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 – represents the basis or 100 percent across all the size and weight measures).

Snapsort Pentax K-3 vs Sony A7 II
Compare K-3 versus A7 II top
Compare K-3 and A7 II rear

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 notably smaller (7 percent) than the Pentax K-3. Moreover, the A7 II is markedly lighter (25 percent) than the K-3. 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.

Concerning battery life, the K-3 gets 560 shots out of its D-LI90 battery, while the A7 II can take 350 images on a single charge of its NP-FW50 power pack.

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
  Camera
Model
Camera
Width
Camera
Height
Camera
Depth
Camera
Weight
Battery
Life
(CIPA)
Weather
Sealing
(yes/no)
Camera
Launch
(announced)
Launch
Price
(USD)
Street
Price
(USD)
Used
Price
(USD)
Camera
Model
Pentax K-3» 5.2 in 3.9 in 3.0 in 28.2 oz 560 Y Oct 2013 1,299- i Pentax K-3
Sony A7 II« 5.0 in 3.8 in 2.4 in 21.1 oz 350 Y Nov 2014 1,999- i Sony A7 II
Canon 70D« » 5.5 in 4.1 in 3.1 in 26.6 oz 920 Y Jul 2013 1,199- i Canon 70D
Nikon D7100« » 5.4 in 4.2 in 3.0 in 27.0 oz 950 Y Feb 2013 1,199- i Nikon D7100
Olympus E-M1 II« » 5.3 in 3.6 in 2.6 in 20.2 oz 440 Y Sep 2016 1,999 i i Olympus E-M1 II
Olympus E-M1« » 5.1 in 3.7 in 2.5 in 17.5 oz 350 Y Sep 2013 1,399- i Olympus E-M1
Panasonic GX8« » 5.2 in 3.1 in 2.5 in 17.2 oz 330 Y Jul 2015 1,199- i Panasonic GX8
Pentax KP« » 5.2 in 4.0 in 3.0 in 24.8 oz 390 Y Jan 2017 1,099 i i Pentax KP
Pentax K-70« » 5.0 in 3.7 in 2.9 in 24.3 oz 410 Y Jun 2016 649 i i Pentax K-70
Pentax K-3 II« » 5.2 in 3.9 in 3.0 in 28.2 oz 720 Y Apr 2015 1,099 i i Pentax K-3 II
Pentax K-5« » 5.2 in 3.8 in 2.9 in 26.8 oz 740 Y Sep 2010 1,099- i Pentax K-5
Sony A7 III« » 5.0 in 3.8 in 2.9 in 22.9 oz 610 Y Feb 2018 1,999 i i Sony A7 III
Sony A7R II« » 5.0 in 3.8 in 2.4 in 22.0 oz 290 Y Jun 2015 3,199- i Sony A7R II
Sony A7« » 5.0 in 3.7 in 1.9 in 16.7 oz 340 Y Oct 2013 1,699- i Sony A7
Sony A7R« » 5.0 in 3.7 in 1.9 in 16.4 oz 340 Y Oct 2013 2,299- i Sony A7R
Sony RX10« » 5.1 in 3.5 in 4.0 in 28.7 oz 420 Y Oct 2013 1,299- i Sony RX10
Sony A99« » 5.8 in 4.4 in 3.1 in 28.6 oz 500 Y Sep 2012 2,799- i Sony A99

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 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: Pentax K-3 vs Sony A7 II

The size of the imaging sensor is a crucial determinant 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 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

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 3.90μm 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

Since 2007, DXO Mark has published sensor performance measurements that have been derived using a consistent methodology. 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 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
Model
Sensor
Class
Resolution
(MP)
Horiz.
Pixels
Vert.
Pixels
Video
Format
DXO
Portrait
DXO
Landscape
DXO
Sports
DXO
Overall
Camera
Model
Pentax K-3» APS-C 24.1 6016 40001080/60i23.713.4121680Pentax K-3
Sony A7 II« Full Frame 24.0 6000 40001080/60p24.913.6244990Sony A7 II
Canon 70D« » APS-C 20.0 5472 36481080/30p22.511.692668Canon 70D
Nikon D7100« » APS-C 24.0 6000 40001080/60p24.213.7125683Nikon D7100
Olympus E-M1 II« » Four Thirds 20.2 5184 38884K/30p23.712.8131280Olympus E-M1 II
Olympus E-M1« » Four Thirds 15.9 4608 34561080/30p23.012.775773Olympus E-M1
Panasonic GX8« » Four Thirds 20.2 5184 38884K/30p23.512.680675Panasonic GX8
Pentax KP« » APS-C 24.1 6016 40001080/60i----Pentax KP
Pentax K-70« » APS-C 24.0 6000 40001080/60i----Pentax K-70
Pentax K-3 II« » APS-C 24.1 6016 40001080/60i23.613.6110680Pentax K-3 II
Pentax K-5« » APS-C 16.1 4928 32641080/25p23.714.1116282Pentax K-5
Sony A7 III« » Full Frame 24.0 6000 40004K/30p25.014.7373096Sony A7 III
Sony A7R II« » Full Frame 42.2 7952 53044K/30p26.013.9343498Sony A7R II
Sony A7« » Full Frame 24.0 6000 40001080/60p24.814.2224890Sony A7
Sony A7R« » Full Frame 36.2 7360 49121080/60p25.614.1274695Sony A7R
Sony RX10« » 1-inch 20.0 5472 36481080/60p22.912.647469Sony RX10
Sony A99« » Full Frame 24.0 6000 40001080/60p25.014.0155589Sony A99

Many modern cameras are not only capable of taking still images, but also of capturing video footage. Both cameras under consideration are equipped with sensors that have a sufficiently high read-out speed for moving images, 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: Pentax K-3 vs Sony A7 II

Apart from 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 table below summarizes some of the other core capabilities of the Pentax K-3 and Sony A7 II in connection with corresponding information for a sample of similar cameras. If needed, the dpreview camera hub, for example, contains further detail on the cameras' specs.

Core Features
  Camera
Model
Viewfinder
(Type or
'000 dots)
Control
Panel
(yes/no)
LCD
Size
(inch)
LCD
Resolution
('000 dots)
LCD
Attach-
ment
Touch
Screen
(yes/no)
Shutter
speed
(1/sec)
Shutter
flaps
(1/sec))
Build-in
Flash
(yes/no)
Build-in
Image
Stab
Camera
Model
Pentax K-3»optical Y 3.2 1037 fixed n 8000 8.3 Y Y Pentax K-3
Sony A7 II«2400 n 3.0 1230 tilting n 8000 5.0 n Y Sony A7 II
Canon 70D« »optical Y 3.0 1040 swivel Y 8000 7.0 Y n Canon 70D
Nikon D7100« »optical Y 3.2 1229 fixed n 8000 6.0 Y n Nikon D7100
Olympus E-M1 II« »2360 n 3.0 1037 swivel Y 8000 18.0 n Y Olympus E-M1 II
Olympus E-M1« »2360 n 3.0 1037 tilting Y 8000 10.0 n Y Olympus E-M1
Panasonic GX8« »2360 n 3.0 1040 swivel Y 8000 10.0 n Y Panasonic GX8
Pentax KP« »optical n 3.0 921 tilting n 6000 7.0 Y Y Pentax KP
Pentax K-70« »optical n 3.0 921 swivel n 6000 6.0 Y Y Pentax K-70
Pentax K-3 II« »optical Y 3.2 1037 fixed n 8000 8.3 n Y Pentax K-3 II
Pentax K-5« »optical Y 3.0 921 fixed n 8000 7.0 Y Y Pentax K-5
Sony A7 III« »2359 n 3.0 922 tilting Y 8000 10.0 n Y Sony A7 III
Sony A7R II« »2400 n 3.0 1229 tilting n 8000 5.0 n Y Sony A7R II
Sony A7« »2400 n 3.0 1230 tilting n 8000 5.0 n n Sony A7
Sony A7R« »2400 n 3.0 1230 tilting n 8000 4.0 n n Sony A7R
Sony RX10« »1440 Y 3.0 1229 tilting n 3200 10.0 Y Y Sony RX10
Sony A99« »2359 Y 3.0 1229 full-flex n 8000 6.0 n Y Sony A99

Both the K-3 and the A7 II have been discontinued, but can regularly be found used on eBay. The K-3 was replaced by the Pentax K-3 II, while the A7 II was followed by the Sony A7 III.

Review summary: Pentax K-3 vs Sony A7 II

So what conclusions can be drawn? Is the Pentax K-3 better than the Sony A7 II or vice versa? Below is a summary of the relative strengths of each of the two contestants.

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Reasons to prefer 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 (1080/60p versus 1080/60i).
  • 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 individual advantages (bullet points above) is taken as a guide, the A7 II emerges as the winner of the match-up (11 : 9 points). However, the relative importance of the various individual camera aspects will vary according to personal preferences and needs, so that you might like to apply corresponding weights to the particular features before making a decision on a new camera.

K-3 09:11 A7 II

In any case, while the comparison of technical specifications can provide a useful overview of the capabilities of different cameras, it says nothing about, for example, the handling, responsiveness, and overall imaging quality of the K-3 and the A7 II 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 why expert reviews are important. The adjacent table relays the overall verdicts of several of the most popular camera review sites (cameralabs, dpreview, ephotozine, imaging-resource, photographyblog). You can find the full text of the reviews by clicking on the site logo in the table header.

Review Scores
  Camera
Model
cameralabs dpreview ephotozine imaging-resource photographyblog Camera
Launch
(announced)
Launch
Price
(USD)
Street
Price
(USD)
Used
Price
(USD)
Camera
Model
Pentax K-3»-83/1005/54.5/55/5 Oct 2013 1,299- i Pentax K-3
Sony A7 II«Rec82/1004.5/55/55/5 Nov 2014 1,999- i Sony A7 II
Canon 70D« »HiRec83/1004.5/54.5/55/5 Jul 2013 1,199- i Canon 70D
Nikon D7100« »HiRec85/1004.5/55/54.5/5 Feb 2013 1,199- i Nikon D7100
Olympus E-M1 II« »HiRec85/1004.5/55/54.5/5 Sep 2016 1,999 i i Olympus E-M1 II
Olympus E-M1« »HiRec84/1004.5/54.5/54.5/5 Sep 2013 1,399- i Olympus E-M1
Panasonic GX8« »Rec82/1004.5/55/54.5/5 Jul 2015 1,199- i Panasonic GX8
Pentax KP« »-82/1005/5-4.5/5 Jan 2017 1,099 i i Pentax KP
Pentax K-70« »-79/1004.5/54/54.5/5 Jun 2016 649 i i Pentax K-70
Pentax K-3 II« »--5/54.5/55/5 Apr 2015 1,099 i i Pentax K-3 II
Pentax K-5« »-83/1005/54.5/54.5/5 Sep 2010 1,099- i Pentax K-5
Sony A7 III« »HiRec89/1005/5-5/5 Feb 2018 1,999 i i Sony A7 III
Sony A7R II« »HiRec90/1005/54.5/55/5 Jun 2015 3,199- i Sony A7R II
Sony A7« »HiRec80/1005/54.5/55/5 Oct 2013 1,699- i Sony A7
Sony A7R« »HiRec82/1004.5/55/55/5 Oct 2013 2,299- i Sony A7R
Sony RX10« »Rec80/1004.5/54.5/54.5/5 Oct 2013 1,299- i Sony RX10
Sony A99« »-84/1004.5/5rev4.5/5 Sep 2012 2,799- i Sony A99

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. Thus, a score needs to be put into the context of the launch date and the launch price of the camera, and rating-comparisons among cameras that span long time periods or concern very differently equipped models make little sense. It should also be noted that some of the review sites have over time altered the way they render their verdicts.

 

Other camera comparisons

Did this review help to inform your camera decision process? If you would like to see a different side-by-side camera review, just make a corresponding selection in the search boxes below. Alternatively, you can follow any of the listed hyperlinks for comparisons that others found interesting. If you cannot find the camera you are interested in, please contact me, and I will try to add information on that model to the database.

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