Olympus E-M1 III vs Sony A7 III
The Olympus OM-D E-M1 Mark III and the Sony Alpha A7 III are two enthusiast cameras that were officially introduced, respectively, in February 2020 and February 2018. Both the E-M1 III and the A7 III are mirrorless interchangeable lens cameras that are based on a Four Thirds (E-M1 III) and a full frame (A7 III) sensor. The Olympus has a resolution of 20.2 megapixels, whereas the Sony provides 24 MP.
Below is an overview of the main specs of the two cameras as a starting point for the comparison.
Going beyond this snapshot of core features and characteristics, what are the differences between the Olympus OM-D E-M1 Mark III and the Sony Alpha A7 III? Which one should you buy? Read on to find out how these two cameras compare with respect to their body size, their imaging sensors, their shooting features, their input-output connections, and their reception by expert reviewers.
The physical size and weight of the Olympus E-M1 III and the Sony A7 III are illustrated in the side-by-side display below. The two cameras are presented according to their relative size. Three consecutive perspectives from the front, the top, and the back are available. All width, height and depth dimensions are rounded to the nearest millimeter.
If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Olympus E-M1 III and the Sony A7 III are of equal size. However, the A7 III is markedly heavier (12 percent) than the E-M1 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 compare the optics available for the two cameras in the Micro Four Thirds Lens Catalog (E-M1 III) and the Sony FE Lens Catalog (A7 III). 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.
Concerning battery life, the E-M1 III gets 420 shots out of its BLH-1 battery, while the A7 III can take 610 images on a single charge of its NP-FZ100 power pack. The battery packs of both cameras can be charged via USB, which can be very convenient when travelling.
The adjacent table lists the principal physical characteristics of the two cameras alongside a wider set of alternatives. If you want to switch the focus of the display and review another camera pair, you can move across to the CAM-parator tool and choose from the broad selection of possible camera comparisons there.
|1.||Olympus E-M1 III||134 mm||91 mm||69 mm||580 g||420||Y||Feb 2020||1,799|
|2.||Sony A7 III||127 mm||96 mm||74 mm||650 g||610||Y||Feb 2018||1,999|
|3.||Nikon Z6||134 mm||101 mm||67 mm||675 g||310||Y||Aug 2018||1,999|
|4.||Olympus E-M10 IV||122 mm||84 mm||49 mm||383 g||360||n||Aug 2020||699|
|5.||Olympus E-M5 III||125 mm||85 mm||50 mm||414 g||310||Y||Oct 2019||1,199|
|6.||Olympus E-M1X||144 mm||147 mm||75 mm||997 g||870||Y||Jan 2019||2,999|
|7.||Olympus E-M1 II||134 mm||91 mm||67 mm||574 g||440||Y||Sep 2016||1,999|
|8.||Olympus E-M1||130 mm||94 mm||63 mm||497 g||350||Y||Sep 2013||1,399|
|9.||Panasonic G95||130 mm||94 mm||77 mm||536 g||290||Y||Apr 2019||999|
|10.||Panasonic G9||137 mm||97 mm||92 mm||658 g||400||Y||Nov 2017||1,699|
|11.||Panasonic GH5||139 mm||98 mm||87 mm||725 g||410||Y||Jan 2017||1,999|
|12.||Panasonic GX8||133 mm||78 mm||63 mm||487 g||330||Y||Jul 2015||1,199|
|13.||Sony A7C||124 mm||71 mm||60 mm||509 g||740||Y||Sep 2020||1,799|
|14.||Sony A7R IV||129 mm||96 mm||78 mm||665 g||670||Y||Jul 2019||3,499|
|15.||Sony A7R III||127 mm||96 mm||74 mm||650 g||650||Y||Oct 2017||3,199|
|16.||Sony A9||127 mm||96 mm||63 mm||673 g||650||Y||Apr 2017||4,499|
|17.||Sony A7 II||127 mm||96 mm||60 mm||599 g||350||Y||Nov 2014||1,999|
|Notes: Measurements and pricing do not include easily detachable parts, such as add-on or interchangeable lenses or optional viewfinders.|
Any camera decision will naturally be influenced heavily by the price. The listed launch prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The E-M1 III was somewhat cheaper (by 10 percent) than the A7 III at launch, but both cameras fall into the same price category. Normally, street prices remain initially close to the MSRP, but after a couple of months, the first discounts appear. 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.
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 Olympus E-M1 III features a Four Thirds sensor and the Sony A7 III a full frame sensor. The sensor area in the A7 III is 276 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 2.0 and 1.0. The sensor in the E-M1 III has a native 4:3 aspect ratio, while the one in the A7 III offers a 3:2 aspect.
With 24MP, the A7 III offers a higher resolution than the E-M1 III (20.2MP), but the A7 III nevertheless has larger individual pixels (pixel pitch of 5.94μm versus 3.34μm for the E-M1 III) due to its larger sensor. However, the E-M1 III is a somewhat more recent model (by 1 year and 11 months) than the A7 III, 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 E-M1 III has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.
The resolution advantage of the Sony A7 III implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A7 III for good quality output (200 dots per inch) amounts to 30 x 20 inches or 76.2 x 50.8 cm, for very good quality (250 dpi) 24 x 16 inches or 61 x 40.6 cm, and for excellent quality (300 dpi) 20 x 13.3 inches or 50.8 x 33.9 cm. The corresponding values for the Olympus E-M1 III are 25.9 x 19.4 inches or 65.8 x 49.4 cm for good quality, 20.7 x 15.6 inches or 52.7 x 39.5 cm for very good quality, and 17.3 x 13 inches or 43.9 x 32.9 cm for excellent quality prints.
Unlike the A7 III, the E-M1 III has the capacity to capture high quality composite images (80MP) 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).
The Olympus OM-D E-M1 Mark III has a native sensitivity range from ISO 200 to ISO 25600, which can be extended to ISO 64-25600. The corresponding ISO settings for the Sony Alpha A7 III are ISO 100 to ISO 51200, with the possibility to increase the ISO range to 50-204800.
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. The following table provides an overview of the physical sensor characteristics, as well as the sensor quality measurements for a selection of comparators.
| DXO |
|1.||Olympus E-M1 III||Four Thirds||20.2||5184||3888||4K/30p||..||..||..||..|
|2.||Sony A7 III||Full Frame||24.0||6000||4000||4K/30p||25.0||14.7||3730||96|
|3.||Nikon Z6||Full Frame||24.3||6048||4024||4K/30p||25.3||14.3||3299||95|
|4.||Olympus E-M10 IV||Four Thirds||20.2||5184||3888||4K/30p||..||..||..||..|
|5.||Olympus E-M5 III||Four Thirds||20.2||5184||3888||4K/30p||..||..||..||..|
|6.||Olympus E-M1X||Four Thirds||20.2||5184||3888||4K/30p||..||..||..||..|
|7.||Olympus E-M1 II||Four Thirds||20.2||5184||3888||4K/30p||23.7||12.8||1312||80|
|8.||Olympus E-M1||Four Thirds||15.9||4608||3456||1080/30p||23.0||12.7||757||73|
|9.||Panasonic G95||Four Thirds||20.2||5184||3888||4K/30p||..||..||..||..|
|10.||Panasonic G9||Four Thirds||20.2||5184||3888||4K/60p||..||..||..||..|
|11.||Panasonic GH5||Four Thirds||20.2||5184||3888||4K/60p||23.9||13.0||807||77|
|12.||Panasonic GX8||Four Thirds||20.2||5184||3888||4K/30p||23.5||12.6||806||75|
|13.||Sony A7C||Full Frame||24.0||6000||4000||4K/30p||25.0||14.7||3407||95|
|14.||Sony A7R IV||Full Frame||60.2||9504||6336||4K/30p||26.0||14.8||3344||99|
|15.||Sony A7R III||Full Frame||42.2||7952||5304||4K/30p||26.0||14.7||3523||100|
|16.||Sony A9||Full Frame||24.0||6000||4000||4K/30p||24.9||13.3||3517||92|
|17.||Sony A7 II||Full Frame||24.0||6000||4000||1080/60p||24.9||13.6||2449||90|
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).
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 E-M1 III offers a slightly higher resolution than the one in the A7 III (2360k vs 2359k dots). The following table reports on some other key feature differences and similarities of the Olympus E-M1 III, the Sony A7 III, and comparable cameras.
|1.||Olympus E-M1 III||2360||n||3.0||1037||swivel||Y||1/8000s||18.0||n||Y|
|2.||Sony A7 III||2359||n||3.0||922||tilting||Y||1/8000s||10.0||n||Y|
|4.||Olympus E-M10 IV||2360||n||3.0||1040||tilting||Y||1/4000s||15.0||Y||Y|
|5.||Olympus E-M5 III||2360||n||3.0||1040||swivel||Y||1/8000s||10.0||n||Y|
|7.||Olympus E-M1 II||2360||n||3.0||1037||swivel||Y||1/8000s||18.0||n||Y|
|14.||Sony A7R IV||5760||n||3.0||1440||tilting||Y||1/8000s||10.0||n||Y|
|15.||Sony A7R III||3686||n||3.0||1440||tilting||Y||1/8000s||10.0||n||Y|
|17.||Sony A7 II||2400||n||3.0||1230||tilting||n||1/8000s||5.0||n||Y|
The reported shutter speed information refers to the use of the mechanical shutter. Yet, some cameras only have an electronic shutter, while others have an electronic shutter in addition to a mechanical one. In fact, both cameras under consideration feature an electronic shutter, which makes completely silent shooting possible. However, this mode is less suitable for photographing moving objects (risk of rolling shutter) or shooting under artificial light sources (risk of flickering).
The Olympus E-M1 III and the Sony A7 III both have an intervalometer built-in. This enables the photographer to capture time lapse sequences, such as flower blooming, a sunset or moon rise, without purchasing an external camera trigger and related software.
The E-M1 III writes its imaging data to SDXC cards, while the A7 III uses SDXC or Memory Stick PRO Duo cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails. Both the E-M1 III and the A7 III support UHS-II cards (Ultra High Speed data transfer of up to 312 MB/s) on the first slot and UHS-I cards (104 MB/s) on the second one.
For some imaging applications, the extent to which a camera can communicate with its environment can be an important aspect in the camera decision process. The table below provides an overview of the connectivity of the Olympus OM-D E-M1 Mark III and Sony Alpha A7 III and, in particular, the interfaces the cameras (and selected comparators) provide for accessory control and data transfer.
| WiFi |
| NFC |
|1.||Olympus E-M1 III||Y||stereo||mono||Y||Y||micro||3.1||Y||-||Y|
|2.||Sony A7 III||Y||stereo||mono||Y||Y||micro||3.1||Y||Y||Y|
|4.||Olympus E-M10 IV||Y||stereo||mono||-||-||micro||2.0||Y||-||Y|
|5.||Olympus E-M5 III||Y||stereo||mono||Y||-||micro||2.0||Y||-||Y|
|7.||Olympus E-M1 II||Y||stereo||mono||Y||Y||micro||3.0||Y||-||-|
|14.||Sony A7R IV||Y||stereo||mono||Y||Y||micro||3.1||Y||Y||Y|
|15.||Sony A7R III||Y||stereo||mono||Y||Y||micro||3.1||Y||Y||Y|
|17.||Sony A7 II||Y||stereo||mono||Y||Y||micro||2.0||Y||Y||-|
Studio photographers will appreciate that the Olympus E-M1 III (unlike the A7 III) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.
Both the E-M1 III and the A7 III are recent models that are part of the current product line-up. The A7 III replaced the earlier Sony A7 II, while the E-M1 III followed on from the Olympus E-M1 II. Further information on the two cameras (e.g. user guides, manuals), as well as related accessories, can be found on the official Olympus and Sony websites.
So what is the bottom line? Is there a clear favorite between the Olympus E-M1 III and the Sony A7 III? Which camera is better? Below is a summary of the relative strengths of each of the two contestants.
Reasons to prefer the Olympus OM-D E-M1 Mark III:
- 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.
- Larger viewfinder image: Features a viewfinder with a higher magnification (0.83x vs 0.78x).
- More detailed LCD: Has a higher resolution rear screen (1037k vs 922k dots).
- More flexible LCD: Has a swivel screen for odd-angle shots in portrait or landscape orientation.
- More selfie-friendly: Has an articulated screen that can be turned to be front-facing.
- Faster burst: Shoots at higher frequency (18 vs 10 flaps/sec) to capture the decisive moment.
- Less heavy: Is lighter (by 70g or 11 percent) and hence easier to carry around.
- Better studio light control: Has a PC Sync socket to connect to professional strobe lights.
- More modern: Is somewhat more recent (announced 1 year and 11 months after the A7 III).
Arguments in favor of the Sony Alpha A7 III:
- More detail: Has more megapixels (24 vs 20.2MP), which boosts linear resolution by 11%.
- Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
- Better image quality: Features bigger pixels on a larger sensor for higher quality imaging.
- Richer colors: The pixel size advantage translates into images with better, more accurate colors.
- More dynamic range: Larger pixels capture a wider spectrum of light and dark details.
- Better low-light sensitivity: Larger pixels means good image quality even under poor lighting.
- Longer lasting: Gets more shots (610 versus 420) out of a single battery charge.
- Easier device pairing: Supports NFC for fast wireless image transfer over short distances.
- More heavily discounted: Has been on the market for longer (launched in February 2018).
If the count of relative strengths (bullet points above) is taken as a measure, the E-M1 III comes out slightly ahead of the A7 III (10 : 9 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 when reflecting and deciding on a new camera. A professional wedding photographer will view the differences between cameras in a way that diverges from the perspective of a travel photog, and a person interested in cityscapes has distinct needs from a macro shooter. Hence, the decision which camera is best and worth buying is often a very personal one.
How about other alternatives? Do the specifications of the Olympus E-M1 III and the Sony A7 III place the cameras among the top in their class? Find out in the latest Best Mirrorless Interchangeable Lens Camera listing whether the two cameras rank among the cream of the crop.
In any case, while the comparison of the spec-sheets of cameras can offer a general idea of their imaging potential, it says little about, for example, the shooting experience and imaging performance of the E-M1 III and the A7 III 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 where reviews by experts come in. The adjacent summary-table relays the overall verdicts of several of the most popular camera review sites (amateurphotographer [AP], cameralabs [CL], dpreview [DPR], ephotozine [EPZ], photographyblog [PB]). As can be seen, the professional reviewers agree in many cases on the quality of different cameras, but sometimes their assessments diverge, reinforcing the earlier point that a camera decision is often a very personal choice.
|1.||Olympus E-M1 III||5/5||..||83/100||4.5/5||4/5||Feb 2020||1,799|
|2.||Sony A7 III||..||+ +||89/100||5/5||5/5||Feb 2018||1,999|
|3.||Nikon Z6||5/5||..||..||4.5/5||5/5||Aug 2018||1,999|
|4.||Olympus E-M10 IV||4.5/5||..||..||4.5/5||4.5/5||Aug 2020||699|
|5.||Olympus E-M5 III||5/5||+||82/100||4.5/5||4.5/5||Oct 2019||1,199|
|6.||Olympus E-M1X||4.5/5||o||..||4.5/5||..||Jan 2019||2,999|
|7.||Olympus E-M1 II||5/5||+ +||85/100||4.5/5||4.5/5||Sep 2016||1,999|
|8.||Olympus E-M1||5/5||+ +||84/100||4.5/5||4.5/5||Sep 2013||1,399|
|9.||Panasonic G95||4.5/5||+||83/100||4.5/5||4.5/5||Apr 2019||999|
|10.||Panasonic G9||..||+ +||85/100||5/5||5/5||Nov 2017||1,699|
|11.||Panasonic GH5||4.5/5||+ +||85/100||4.5/5||5/5||Jan 2017||1,999|
|12.||Panasonic GX8||5/5||+||82/100||4.5/5||4.5/5||Jul 2015||1,199|
|13.||Sony A7C||3.5/5||..||86/100||4/5||4/5||Sep 2020||1,799|
|14.||Sony A7R IV||5/5||+||91/100||4.5/5||5/5||Jul 2019||3,499|
|15.||Sony A7R III||..||+ +||90/100||4.5/5||5/5||Oct 2017||3,199|
|16.||Sony A9||5/5||+ +||89/100||5/5||5/5||Apr 2017||4,499|
|17.||Sony A7 II||5/5||+||82/100||4.5/5||5/5||Nov 2014||1,999|
|Notes: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.|
The above review scores should be interpreted with care, though. The ratings are only valid when referring to cameras in the same category and of the same age. A score, therefore, has to be seen in close connection to the price and market introduction time 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 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 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.
Specifications: Olympus E-M1 III vs Sony A7 III
Below is a side-by-side comparison of the specs of the two cameras to facilitate a quick review of their differences and common features.
|Camera Model||Olympus E-M1 III||Sony A7 III|
|Camera Type||Mirrorless system camera||Mirrorless system camera|
|Camera Lens||Micro Four Thirds lenses||Sony E mount lenses|
|Launch Date||February 2020||February 2018|
|Launch Price||USD 1,799||USD 1,999|
|Sensor Specs||Olympus E-M1 III||Sony A7 III|
|Sensor Format||Four Thirds Sensor||Full Frame Sensor|
|Sensor Size||17.3 x 13.0 mm||35.6 x 23.8 mm|
|Sensor Area||224.9 mm2||847.28 mm2|
|Sensor Diagonal||21.6 mm||42.8 mm|
|Sensor Resolution||20.2 Megapixels||24 Megapixels|
|Image Resolution||5184 x 3888 pixels||6000 x 4000 pixels|
|Pixel Pitch||3.34 μm||5.94 μm|
|Pixel Density||8.96 MP/cm2||2.83 MP/cm2|
|Moiré control||no AA filter||Anti-Alias filter|
|Movie Capability||4K/30p Video||4K/30p Video|
|ISO Setting||200 - 25,600 ISO||100 - 51,200 ISO|
|ISO Boost||64 - 25,600 ISO||50 - 204,800 ISO|
|Image Processor||TruePic IX||BIONZ X|
|DXO Sensor Quality (score)||..||96|
|DXO Color Depth (bits)||..||25.0|
|DXO Dynamic Range (EV)||..||14.7|
|DXO Low Light (ISO)||..||3730|
|Screen Specs||Olympus E-M1 III||Sony A7 III|
|Viewfinder Type||Electronic viewfinder||Electronic viewfinder|
|Viewfinder Field of View||100%||100%|
|Viewfinder Resolution||2360k dots||2359k dots|
|LCD Framing||Live View||Live View|
|Rear LCD Size||3.0inch||3.0inch|
|LCD Resolution||1037k dots||922k dots|
|LCD Attachment||Swivel screen||Tilting screen|
|Shooting Specs||Olympus E-M1 III||Sony A7 III|
|Focus System||On-Sensor Phase-detect||On-Sensor Phase-detect|
|Manual Focusing Aid||Focus Peaking||Focus Peaking|
|Max Shutter Speed (mechanical)||1/8000s||1/8000s|
|Continuous Shooting||18 shutter flaps/s||10 shutter flaps/s|
|Shutter Life Expectancy||400 000 actuations||200 000 actuations|
|Electronic Shutter||up to 1/32000s||YES|
|Time-Lapse Photography||Intervalometer built-in||Intervalometer built-in|
|Image Stabilization||In-body stabilization||In-body stabilization|
|Fill Flash||no On-Board Flash||no On-Board Flash|
|Storage Medium||SDXC cards||MS or SDXC cards|
|Second Storage Option||Dual card slots||Dual card slots|
|UHS card support||Single UHS-II||Single UHS-II|
|Connectivity Specs||Olympus E-M1 III||Sony A7 III|
|Studio Flash||PC Sync socket||no PC Sync|
|USB Connector||USB 3.1||USB 3.1|
|HDMI Port||micro HDMI||micro HDMI|
|Microphone Port||External MIC port||External MIC port|
|Headphone Socket||Headphone port||Headphone port|
|Wifi Support||Wifi built-in||Wifi built-in|
|Near-Field Communication||no NFC||NFC built-in|
|Bluetooth Support||Bluetooth built-in||Bluetooth built-in|
|Body Specs||Olympus E-M1 III||Sony A7 III|
|Environmental Sealing||Weathersealed body||Weathersealed body|
|Battery Life (CIPA)||420 shots per charge||610 shots per charge|
|In-Camera Charging||USB charging||USB charging|
134 x 91 x 69 mm
(5.3 x 3.6 x 2.7 in)
127 x 96 x 74 mm
(5.0 x 3.8 x 2.9 in)
|Camera Weight||580 g (20.5 oz)||650 g (22.9 oz)|
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