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Pentax K-3 versus Panasonic GX8

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

Body comparison

The physical size and weight of the Pentax K-3 and the Panasonic GX8 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 dimensions are rounded to the nearest millimeter. You can also toggle the display 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 K-3 – represents the basis for the calculations across all the size and weight measures).

Pentax K-3 vs Panasonic GX8 front
K-3 versus GX8 top view
K-3 and GX8 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 Panasonic GX8 is notably smaller (21 percent) than the Pentax K-3. Moreover, the GX8 is substantially lighter (39 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.

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
Panasonic GX8 (⇒ lft) 133 mm 78 mm 63 mm 487 g 330 YES 2015 1,199 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 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
Olympus E-M1 (⇒ lft | rgt) 130 mm 94 mm 63 mm 497 g 350 YES 2013 1,399discont. check
Panasonic GH5 (⇒ lft | rgt) 139 mm 98 mm 87 mm 725 g 410 YES 2017 1,999 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 A7 II (⇒ lft | rgt) 127 mm 96 mm 60 mm 599 g 350 YES 2014 1,999 latest 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 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 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 features an APS-C sensor and the Panasonic GX8 a Four Thirds sensor. The sensor area in the GX8 is 39 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.5 and 2.0. The sensor in the K-3 has a native 3:2 aspect ratio, while the one in the GX8 offers a 4:3 aspect.

Pentax K-3 and Panasonic GX8 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 pixels. 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 GX8 MP
Sensor resolution

Since 2007, DXO Mark has published sensor performance measurements that have been derived using a consistent methodology. 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 review, the K-3 has a notably higher overall DXO score than the GX8 (overall score 5 points higher), which gives it an advantage in terms of imaging quality. This 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 table below summarizes the physical sensor characteristics and sensor quality findings and compares them across a set of similar cameras.

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
Panasonic GX8 (⇒ lft) Four Thirds 20.2 5184 3888 4K/30p 23.5 12.6 806 75
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 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
Olympus E-M1 (⇒ lft | rgt) Four Thirds 15.9 4608 3456 1080/30p 23.0 12.7 757 73
Panasonic GH5 (⇒ lft | rgt) Four Thirds 20.2 5184 3888 4K/60p 23.9 13.0 807 77
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 A7 II (⇒ lft | rgt) Full Frame 24.0 6000 4000 1080/60p 24.9 13.6 2449 90
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 cannot only take still pictures, but also record videos. Both cameras under consideration are equipped with sensors that have a sufficiently high read-out speed for moving images, but the GX8 provides a better video resolution than the K-3. It can shoot movie 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 following table reports on some other key feature differences and similarities of the Pentax K-3, the Panasonic GX8, and comparable cameras. 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
Pentax K-3 (⇒ rgt) optical YES 3.2 1037 fixed no 8000 8.3 13 YES
Panasonic GX8 (⇒ lft) 2360 no 3.0 1040 swivel YES 8000 10.0 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 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
Olympus E-M1 (⇒ lft | rgt) 2360 no 3.0 1037 tilting YES 8000 10.0 no YES
Panasonic GH5 (⇒ lft | rgt) 3680 no 3.2 1620 swivel YES 8000 12.0 no 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 A7 II (⇒ lft | rgt) 2400 no 3.0 1230 tilting no 8000 5.0 no YES
Sony RX10 (⇒ lft | rgt) 1440 YES 3.0 1229 tilting no 3200 10.0 10.2 YES
Sony A99 (⇒ lft | rgt) 2359 YES 3.0 1229 full-flex no 8000 6.0 no 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 is the bottom line? Is there a clear favorite between the Pentax K-3 and the Pentax K-3? A synthesis of the relative strong points of each of the models is listed below.


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Reasons to prefer the Pentax K-3:

  • More detail: Offers more megapixels (24.1 vs 20.2MP) with a 11% higher linear resolution.
  • 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 assessment.
  • More dynamic range: Captures a larger spectrum of light and dark details (0.8 EV of extra DR).
  • Better low-light sensitivity: Requires less light for good images (0.6 stops ISO advantage).
  • 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 (560 versus 330) on a single battery charge.
  • Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
  • More heavily discounted: Has been on the market for longer (launched in October 2013).

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Arguments in favor 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: 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.
  • More compact: Is smaller (133x78mm vs 131x100mm) and will fit more readily into a bag.
  • Less heavy: Has a lower weight (by 313g or 39 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 9 months) more recently.

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

K-3 11:10 GX8

In any case, while the specs-based evaluation of cameras is instructive in revealing their potential as photographic tools, it says nothing about, for example, the handling, responsiveness, and overall imaging quality of the K-3 and the GX8 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 where reviews by experts come in. The table below summarizes the assessments of some of the best known camera review sites. You can find the full text of the reviews, 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
Panasonic GX8 (⇒ lft) Rec 82/100 Silver 4.5/5 5/5 4.5/5 2015 1,199 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 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
Olympus E-M1 (⇒ lft | rgt) HiRec 84/100 Gold 4.5/5 4.5/5 4.5/5 2013 1,399discont. check
Panasonic GH5 (⇒ lft | rgt) HiRec 85/100 Gold 4.5/5 5/5 5/5 2017 1,999 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 A7 II (⇒ lft | rgt) Rec 82/100 Silver 4.5/5 5/5 5/5 2014 1,999 latest 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

Care should be taken when interpreting the review scores above, though. The ratings are only valid when refering to cameras in the same category and of the same age. 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, please note that some of the review sites have changed their methodology and reporting over time.

Other comparisons

In case you would like to check on the differences and similarities of other camera models, just make your choice using the following search menu. 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 send me an email, and I will try to locate and add the respective data to the application.

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