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Sony A7R III versus Panasonic GX8

The Sony Alpha A7R III and the Panasonic Lumix DMC-GX8 are two enthusiast cameras that were officially introduced, respectively, in October 2017 and July 2015. Both the A7R III and the GX8 are mirrorless interchangeable lens cameras that are based on a full frame (A7R III) and a Four Thirds sensor. The Sony has a resolution of 42.2 megapixel, whereas the Panasonic provides 20.2 MP.

Body comparison

The physical size and weight of the Sony A7R III and the Panasonic GX8 are illustrated in the side-by-side display below. Three consecutive views from the front, the top, and the rear side are shown. All size 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 – the A7R III – represents the basis or 100 percent across all the size and weight measures).

Sony A7R III vs Panasonic GX8 front
A7R III versus GX8 top view
A7R III and GX8 rear side
Body view (A7R III 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 (15 percent) than the Sony A7R III. Moreover, the GX8 is markedly lighter (25 percent) than the A7R III. 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. A larger imaging sensor will tend to go along with bigger and heavier lenses, although exceptions exist. You can find an overview of optics for the two cameras in the Sony FE Lens Catalog (A7R III) and the Micro Four Thirds Lens Catalog (GX8). Mirrorless cameras, such as the two under consideration, have the additional advantage of having a short flange to focal plane distance, which makes it possible to mount many lenses from other systems onto the camera via adapters.

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)
Sony A7R III (⇒ rgt) 127 mm 96 mm 74 mm 650 g 650 YES 2017 3,199 latest check
Panasonic GX8 (⇒ lft) 133 mm 78 mm 63 mm 487 g 330 YES 2015 1,199 latest check
Nikon D850 (⇒ lft | rgt) 146 mm 124 mm 79 mm 1005 g 1840 YES 2017 3,299 latest 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 GX7 (⇒ lft | rgt) 123 mm 71 mm 55 mm 402 g 350 no 2013 999discont. check
Pentax K-1 (⇒ lft | rgt) 137 mm 110 mm 86 mm 1010 g 760 YES 2016 1,799 latest check
Sony A9 (⇒ lft | rgt) 127 mm 96 mm 63 mm 673 g 650 YES 2017 4,499 latest check
Sony A99 II (⇒ lft | rgt) 143 mm 104 mm 76 mm 849 g 490 YES 2016 3,199 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 A7 II (⇒ lft | rgt) 127 mm 96 mm 60 mm 599 g 350 YES 2014 1,999 latest check
Sony A7R (⇒ lft | rgt) 127 mm 94 mm 48 mm 465 g 340 YES 2013 2,299discont. 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 launched at a markedly lower price (by 63 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

The size of the sensor inside a digital camera is one of the key determinants 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. 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 associated with larger, more expensive camera bodies and lenses.

Of the two cameras under consideration, the Sony A7R III features a full frame sensor and the Panasonic GX8 a Four Thirds sensor. The sensor area in the GX8 is 74 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.0 and 2.0. The sensor in the A7R III has a native 3:2 aspect ratio, while the one in the GX8 offers a 4:3 aspect.

Sony A7R III and Panasonic GX8 sensor measures
Sensor size
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Sensor size

With 42.2MP, the A7R III offers a higher resolution than the GX8 (20.2MP), but the A7R III nevertheless has larger individual pixels (pixel pitch of 4.52μm versus 3.34μm for the GX8) due to its larger sensor. Moreover, the A7R III is a somewhat more recent model (by 2 years and 3 months) than the GX8, and its sensor might have benefitted from technological advances during this time that further enhance the light gathering capacity of its pixels. Coming back to sensor resolution, it should be mentioned that the A7R III has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

Unlike the GX8, the A7R III has the capacity to capture high quality composite images by combining multiple shots after shifting its sensor by miniscule distances. This multi-shot, pixel-shift mode is most suitable for photography of stationary objects (landscapes, studio scenes).

A7R III versus GX8 MP
Sensor resolution
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Sensor resolution

Consistent information on actual sensor performance is available from DXO Mark for most cameras. 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. 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
Sony A7R III (⇒ rgt) Full Frame 42.2 7952 5304 4K/30p .. .. .. ..
Panasonic GX8 (⇒ lft) Four Thirds 20.2 5184 3888 4K/30p 23.5 12.6 806 75
Nikon D850 (⇒ lft | rgt) Full Frame 45.4 8256 5504 4K/30p 26.4 14.8 2660 100
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 GX7 (⇒ lft | rgt) Four Thirds 15.8 4592 3448 1080/60p 22.6 12.2 718 70
Pentax K-1 (⇒ lft | rgt) Full Frame 36.2 7360 4912 1080/60i 25.4 14.6 3280 96
Sony A9 (⇒ lft | rgt) Full Frame 24.0 6000 4000 4K/30p 24.9 13.3 3517 92
Sony A99 II (⇒ lft | rgt) Full Frame 42.2 7952 5304 4K/30p 25.4 13.4 2317 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 A7 II (⇒ lft | rgt) Full Frame 24.0 6000 4000 1080/60p 24.9 13.6 2449 90
Sony A7R (⇒ lft | rgt) Full Frame 36.2 7360 4912 1080/60p 25.6 14.1 2746 95
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 can also record movies. Both cameras under consideration have a sensor with sufficiently fast read-out times for moving pictures, and both provide the same movie specifications (4K/30p).

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. The two cameras under consideration are similar with respect to both having an electronic viewfinder. However, the one in the A7R III offers a substantially higher resolution than the one in the GX8 (3686k vs 2360k dots). The following table reports on some other key feature differences and similarities of the Sony A7R III, the Panasonic GX8, and comparable cameras. If you need more detail on the specs, you can find comprehensive listings, 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
Sony A7R III (⇒ rgt) 3686 no 3.0 1440 tilting YES 8000 10.0 no YES
Panasonic GX8 (⇒ lft) 2360 no 3.0 1040 swivel YES 8000 10.0 no YES
Nikon D850 (⇒ lft | rgt) optical YES 3.2 2359 tilting YES 8000 9.0 no 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 GX7 (⇒ lft | rgt) 2760 no 3.0 1040 tilting YES 8000 5.0 7 YES
Pentax K-1 (⇒ lft | rgt) optical YES 3.2 1037 full-flex no 8000 4.4 no YES
Sony A9 (⇒ lft | rgt) 3686 no 3.0 1440 tilting YES 8000 20.0 no YES
Sony A99 II (⇒ lft | rgt) 2400 YES 3.0 1229 tilting no 8000 12.0 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 A7 II (⇒ lft | rgt) 2400 no 3.0 1230 tilting no 8000 5.0 no YES
Sony A7R (⇒ lft | rgt) 2400 no 3.0 1230 tilting no 8000 4.0 no no
Sony A99 (⇒ lft | rgt) 2359 YES 3.0 1229 full-flex no 8000 6.0 no YES

Both the A7R III and the GX8 are current models that good online retailers will have in stock. You can check the latest prices, for example, at amazon. The GX8 replaced the earlier Panasonic GX7, while the A7R III followed on from the Sony A7R II.

Summary

So what conclusions can be drawn? Is the Sony A7R III better than the Panasonic GX8 or vice versa? A synthesis of the relative strong points of each of the models is listed below.


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Advantages of the Sony Alpha A7R III:

  • More detail: Offers more megapixels (42.2 vs 20.2MP) with a 48% higher linear resolution.
  • Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
  • High quality composites: Can combine several shots after pixel-shifting its sensor.
  • Better image quality: Features a larger and more technologically advanced imaging sensor.
  • More detailed viewfinder: Has a higher resolution electronic viewfinder (3686k vs 2360k dots).
  • More detailed LCD: Has a higher resolution rear screen (1440k vs 1040k dots).
  • Longer lasting: Can take more shots (650 versus 330) on a single battery charge.
  • More modern: Reflects 2 years and 3 months of technical progress since the GX8 launch.

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Reasons to prefer the Panasonic Lumix DMC-GX8:

  • Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
  • More flexible LCD: Has a swivel screen for odd-angle shots in portrait or landscape orientation.
  • More compact: Is smaller (133x78mm vs 127x96mm) and will fit more readily into a bag.
  • Less heavy: Has a lower weight (by 163g or 25 percent) and is thus easier to take along.
  • More affordable: Was introduced into a lower priced category (63 percent cheaper at launch).
  • More heavily discounted: Has been around for much longer (launched in July 2015).

If the count of individual advantages (bullet points above) is taken as a guide, the A7R III emerges as the winner of the contest (8 : 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.

A7R III 08:06 GX8

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 A7R III or the GX8 handle or perform in practice. User reviews, such as those found at amazon, can sometimes inform about these issues, but such feedback is often incomplete, inconsistent, and biased. This is where reviews by experts come in. 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)
Sony A7R III (⇒ rgt) .. .. .. .. .. 2017 3,199 latest check
Panasonic GX8 (⇒ lft) Rec 82/100 Silver 4.5/5 5/5 4.5/5 2015 1,199 latest check
Nikon D850 (⇒ lft | rgt) .. 89/100 Gold 4.5/5 .. 5/5 2017 3,299 latest 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 GX7 (⇒ lft | rgt) Rec 79/100 Silver 5/5 4.5/5 5/5 2013 999discont. check
Pentax K-1 (⇒ lft | rgt) - 84/100 Silver 5/5 4.5/5 5/5 2016 1,799 latest check
Sony A9 (⇒ lft | rgt) .. 89/100 Gold 5/5 5/5 5/5 2017 4,499 latest check
Sony A99 II (⇒ lft | rgt) - 85/100 Silver 4.5/5 4.5/5 4.5/5 2016 3,199 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 A7 II (⇒ lft | rgt) Rec 82/100 Silver 4.5/5 5/5 5/5 2014 1,999 latest check
Sony A7R (⇒ lft | rgt) HiRec 82/100 Gold 4.5/5 5/5 5/5 2013 2,299discont. check
Sony A99 (⇒ lft | rgt) - 84/100 Gold 4.5/5 reviewed 4.5/5 2012 2,799discont. check

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.

Other comparisons

In case you are interested in seeing how other cameras pair up, 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 contact me, and I will try to locate and add the respective data to the application.

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