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Panasonic GX8 versus Pentax K-3

The Panasonic Lumix DMC-GX8 and the Pentax K-3 are two enthusiast cameras that were announced, respectively, in July 2015 and October 2013. The GX8 is a mirrorless interchangeable lens camera, while the K-3 is a DSLR. The cameras are based on a Four Thirds (GX8) and an APS-C sensor. The Panasonic has a resolution of 20.2 megapixel, whereas the Pentax provides 24.1 MP.

Body comparison

The physical size and weight of the Panasonic GX8 and the Pentax K-3 are illustrated in the side-by-side display below. Three consecutive perspectives from the front, the top, and the back are presented. All width, height and depth dimensions 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 side – the GX8 – represents the basis for the calculations across all the size and weight measures).

Panasonic GX8 vs Pentax K-3 front
GX8 versus K-3 top view
GX8 and K-3 rear side
Body view (GX8 on the left)

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Pentax K-3 is notably larger (26 percent) than the Panasonic GX8. Moreover, the K-3 is substantially heavier (64 percent) than the GX8. 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)
Panasonic GX8 (⇒ rgt) 133 mm 78 mm 63 mm 487 g 330 YES 2015 1,199 latest check
Pentax K-3 (⇒ lft) 131 mm 100 mm 77 mm 800 g 560 YES 2013 1,299discont. check
Canon 70D (⇒ lft | rgt) 139 mm 104 mm 79 mm 755 g 920 YES 2013 1,199discont. check
Olympus E-M1 II (⇒ lft | rgt) 134 mm 91 mm 67 mm 574 g 440 YES 2016 1,999 latest check
Olympus PEN-F (⇒ lft | rgt) 125 mm 72 mm 37 mm 427 g 330 no 2016 1,199 latest check
Olympus E-M5 II (⇒ lft | rgt) 124 mm 85 mm 45 mm 469 g 310 YES 2015 1,099 latest check
Panasonic GH5 (⇒ lft | rgt) 139 mm 98 mm 87 mm 725 g 410 YES 2017 1,999 latest check
Panasonic G80 (⇒ lft | rgt) 128 mm 89 mm 74 mm 505 g 330 YES 2016 899 latest check
Panasonic GX80 (⇒ lft | rgt) 122 mm 71 mm 44 mm 426 g 290 no 2016 799 latest check
Panasonic GX7 (⇒ lft | rgt) 123 mm 71 mm 55 mm 402 g 350 no 2013 999discont. check
Pentax KP (⇒ lft | rgt) 132 mm 101 mm 76 mm 703 g 390 YES 2017 1,099 latest check
Pentax K-70 (⇒ lft | rgt) 126 mm 93 mm 74 mm 688 g 410 YES 2016 649 latest check
Pentax K-3 II (⇒ lft | rgt) 131 mm 100 mm 77 mm 800 g 720 YES 2015 1,099 latest check
Sony A6300 (⇒ lft | rgt) 120 mm 67 mm 49 mm 404 g 400 YES 2016 999discont. check
Sony A6500 (⇒ lft | rgt) 120 mm 67 mm 53 mm 453 g 350 YES 2016 1,399 latest check
Sony RX10 (⇒ lft | rgt) 129 mm 88 mm 102 mm 813 g 420 YES 2013 1,299discont. check

The listed prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The GX8 was somewhat cheaper (by 8 percent) than the K-3 at launch, but both cameras fall into the same price category. 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 imaging sensor is at the core of digital cameras and its size is one of the main determining factors 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 Panasonic GX8 features a Four Thirds sensor and the Pentax K-3 an APS-C sensor. The sensor area in the K-3 is 63 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 2.0 and 1.5. The sensor in the GX8 has a native 4:3 aspect ratio, while the one in the K-3 offers a 3:2 aspect.

Panasonic GX8 and Pentax K-3 sensor measures
Sensor size

With 24.1MP, the K-3 offers a higher resolution than the GX8 (20.2MP), but the K-3 nevertheless has larger individual pixels (pixel pitch of 3.90μm versus 3.34μm for the GX8) due to its larger sensor. However, the GX8 is a somewhat more recent model (by 1 year and 9 months) than the K-3, and its sensor might have benefitted from technological advances during this time that 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.

GX8 versus K-3 MP
Sensor resolution

Consistent information on actual sensor performance is available from DXO Mark for most cameras. 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"). Of the two cameras under consideration, the K-3 has a markedly higher DXO score than the GX8 (overall score 5 points higher), which will translate into better image quality. The advantage is based on 0.2 bits higher color depth, 0.8 EV in additional dynamic range, and 0.6 stops in additional low light sensitivity. The adjacent table reports on the physical sensor characteristics and the outcomes of the DXO sensor quality tests for a sample of comparator-cameras.

Sensor Characteristics
Camera Sensor
Class
Resolution
(Megapixel)
Horiz.
Pixels
Vert.
Pixels
Video
Format
DXO
Portrait
DXO
Landscape
DXO
Sports
DXO
Overall
Panasonic GX8 (⇒ rgt) Four Thirds 20.2 5184 3888 4K/30p 23.5 12.6 806 75
Pentax K-3 (⇒ lft) APS-C 24.1 6016 4000 1080/60i 23.7 13.4 1216 80
Canon 70D (⇒ lft | rgt) APS-C 20.0 5472 3648 1080/30p 22.5 11.6 926 68
Olympus E-M1 II (⇒ lft | rgt) Four Thirds 20.2 5184 3888 4K/30p 23.7 12.8 1312 80
Olympus PEN-F (⇒ lft | rgt) Four Thirds 20.2 5184 3888 1080/60p 23.1 12.4 894 74
Olympus E-M5 II (⇒ lft | rgt) Four Thirds 15.9 4608 3456 1080/60p 23.0 12.5 842 73
Panasonic GH5 (⇒ lft | rgt) Four Thirds 20.2 5184 3888 4K/60p 23.9 13.0 807 77
Panasonic G80 (⇒ lft | rgt) Four Thirds 15.8 4592 3448 4K/30p 22.8 12.5 656 71
Panasonic GX80 (⇒ lft | rgt) Four Thirds 15.8 4592 3448 4K/30p 22.9 12.6 662 71
Panasonic GX7 (⇒ lft | rgt) Four Thirds 15.8 4592 3448 1080/60p 22.6 12.2 718 70
Pentax KP (⇒ lft | rgt) APS-C 24.1 6016 4000 1080/60i - - - -
Pentax K-70 (⇒ lft | rgt) APS-C 24.0 6000 4000 1080/60i - - - -
Pentax K-3 II (⇒ lft | rgt) APS-C 24.1 6016 4000 1080/60i 23.6 13.6 1106 80
Sony A6300 (⇒ lft | rgt) APS-C 24.0 6000 4000 4K/30p 24.4 13.7 1437 85
Sony A6500 (⇒ lft | rgt) APS-C 24.0 6000 4000 4K/30p 24.5 13.7 1405 85
Sony RX10 (⇒ lft | rgt) 1-inch 20.0 5472 3648 1080/60p 22.9 12.6 474 69

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 GX8 provides a higher video resolution than the K-3. It can shoot video footage at 4K/30p, while the Pentax is limited to 1080/60i.

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. For example, the GX8 has an electronic viewfinder (2360k 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 Panasonic GX8 and Pentax K-3 along with similar information for a selection of comparators. If needed, the dpreview camera hub, for example, contains further detail on the cameras' specs.

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
Panasonic GX8 (⇒ rgt) 2360 no 3.0 1040 swivel YES 8000 10.0 no YES
Pentax K-3 (⇒ lft) optical YES 3.2 1037 fixed no 8000 8.3 13 YES
Canon 70D (⇒ lft | rgt) optical YES 3.0 1040 swivel YES 8000 7.0 12 no
Olympus E-M1 II (⇒ lft | rgt) 2360 no 3.0 1037 swivel YES 8000 18.0 no YES
Olympus PEN-F (⇒ lft | rgt) 2360 no 3.0 1037 swivel YES 8000 10.0 no YES
Olympus E-M5 II (⇒ lft | rgt) 2360 no 3.0 1037 swivel YES 8000 10.0 no YES
Panasonic GH5 (⇒ lft | rgt) 3680 no 3.2 1620 swivel YES 8000 12.0 no YES
Panasonic G80 (⇒ lft | rgt) 2360 no 3.0 1040 swivel YES 4000 9.0 6.2 YES
Panasonic GX80 (⇒ lft | rgt) 2765 no 3.0 1040 tilting YES 4000 8.0 6 YES
Panasonic GX7 (⇒ lft | rgt) 2760 no 3.0 1040 tilting YES 8000 5.0 7 YES
Pentax KP (⇒ lft | rgt) optical no 3.0 921 tilting no 6000 7.0 YES YES
Pentax K-70 (⇒ lft | rgt) optical no 3.0 921 swivel no 6000 6.0 YES YES
Pentax K-3 II (⇒ lft | rgt) optical YES 3.2 1037 fixed no 8000 8.3 no YES
Sony A6300 (⇒ lft | rgt) 2300 no 3.0 922 tilting no 4000 11.0 6 no
Sony A6500 (⇒ lft | rgt) 2300 no 3.0 922 tilting YES 4000 11.0 6 YES
Sony RX10 (⇒ lft | rgt) 1440 YES 3.0 1229 tilting no 3200 10.0 10.2 YES

The GX8 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 Panasonic GX8 better than the Pentax K-3 or vice versa? The listing below highlights the relative strengths of the two models.


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Advantages of the Panasonic Lumix DMC-GX8:

  • Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
  • Better video: Provides higher definition movie capture (4K/30p vs 1080/60i).
  • More framing info: Has an electronic viewfinder that displays shooting data.
  • More flexible LCD: Has swivel screen for odd-angle shots in portrait or landscape orientation.
  • Fewer buttons to press: Is equipped with a touch-sensitive rear screen to facilitate handling.
  • Faster burst: Shoots at higher frequency (10 vs 8.3 flaps/sec) to capture the decisive moment.
  • More compact: Is smaller (133x78mm vs 131x100mm) and thus needs less room in the bag.
  • Less heavy: Is lighter (by 313g or 39 percent) and hence easier to carry around.
  • More legacy lens friendly: Can take a broad range of non-native lenses via adapters.
  • More modern: Is somewhat more recent (announced 1 year and 9 months after the K-3).

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Arguments in favor of the Pentax K-3:

  • More detail: Has more megapixels (24.1 vs 20.2MP), which boosts linear resolution by 11%.
  • Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
  • Better image quality: Scores markedly higher (5 points) in the DXO overall evaluation.
  • More dynamic range: Captures a broader range of light and dark details (0.8 EV of extra DR).
  • Better low-light sensitivity: Can shoot in dim conditions (0.6 stops ISO advantage).
  • Brighter framing: Features an optical viewfinder for clear, lag-free composition.
  • Easier setting verification: Has a control panel on top to check shooting parameters.
  • Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
  • Longer lasting: Gets more shots (560 versus 330) out of a single battery charge.
  • Easier fill-in: Has a small integrated flash to brighten shadows of backlit subjects.
  • More heavily discounted: Has been on the market for longer (launched in October 2013).

If the number of relative strengths (bullet points above) is taken as a guide, the K-3 comes out slightly ahead of the GX8 (11 : 10 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.

GX8 10:11 K-3

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 GX8 and the K-3 in practical situations. 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 detailed reviews can be accessed, respectively, on the websites of 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)
Panasonic GX8 (⇒ rgt) Rec 82/100 Silver 4.5/5 5/5 4.5/5 2015 1,199 latest check
Pentax K-3 (⇒ lft) - 83/100 Gold 5/5 4.5/5 5/5 2013 1,299discont. check
Canon 70D (⇒ lft | rgt) HiRec 83/100 Gold 4.5/5 4.5/5 5/5 2013 1,199discont. check
Olympus E-M1 II (⇒ lft | rgt) HiRec 85/100 Gold 4.5/5 5/5 4.5/5 2016 1,999 latest check
Olympus PEN-F (⇒ lft | rgt) - 82/100 Silver 4.5/5 4.5/5 5/5 2016 1,199 latest check
Olympus E-M5 II (⇒ lft | rgt) HiRec 81/100 Silver 5/5 4.5/5 5/5 2015 1,099 latest check
Panasonic GH5 (⇒ lft | rgt) HiRec 85/100 Gold 4.5/5 5/5 5/5 2017 1,999 latest check
Panasonic G80 (⇒ lft | rgt) HiRec 84/100 Gold 5/5 4.5/5 4.5/5 2016 899 latest check
Panasonic GX80 (⇒ lft | rgt) HiRec 82/100 Silver 5/5 4.5/5 5/5 2016 799 latest check
Panasonic GX7 (⇒ lft | rgt) Rec 79/100 Silver 5/5 4.5/5 5/5 2013 999discont. check
Pentax KP (⇒ lft | rgt) - 82/100 Silver 5/5 - 4.5/5 2017 1,099 latest check
Pentax K-70 (⇒ lft | rgt) - 79/100 Silver 4.5/5 4/5 4.5/5 2016 649 latest check
Pentax K-3 II (⇒ lft | rgt) - - 5/5 4.5/5 5/5 2015 1,099 latest check
Sony A6300 (⇒ lft | rgt) Rec 85/100 Gold 5/5 5/5 5/5 2016 999discont. check
Sony A6500 (⇒ lft | rgt) HiRec 85/100 Silver 4.5/5 5/5 4.5/5 2016 1,399 latest check
Sony RX10 (⇒ lft | rgt) Rec 80/100 Gold 4.5/5 4.5/5 4.5/5 2013 1,299discont. 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. 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. Also, please note that some of the review sites have changed their methodology and reporting over time.

Other comparisons

If you would like to see a different side-by-side camera review, just use the search menu below. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored. If you do not see the camera that you are looking for, kindly get in touch, and I will try to add information on that model to the database.

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