Olympus E-M1 III vs Sony A7
The Olympus OM-D E-M1 Mark III and the Sony Alpha A7 are two enthusiast cameras that were officially introduced, respectively, in February 2020 and October 2013. Both the E-M1 III and the A7 are mirrorless interchangeable lens cameras that are based on a Four Thirds (E-M1 III) and a full frame (A7) 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? 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.
An illustration of the physical size and weight of the Olympus E-M1 III and the Sony A7 is provided in the side-by-side display below. The two cameras are presented according to their relative size. 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.
If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Sony A7 is somewhat smaller (2 percent) than the Olympus E-M1 III. Moreover, the A7 is markedly lighter (18 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). 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 can take 340 images on a single charge of its NP-FW50 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||127 mm||94 mm||48 mm||474 g||340||Y||Oct 2013||1,699|
|3.||Fujifilm X-H1||140 mm||97 mm||86 mm||673 g||310||Y||Feb 2018||1,899|
|4.||Nikon Z6 II||134 mm||101 mm||70 mm||705 g||410||Y||Oct 2020||1,999|
|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.||Panasonic G90||130 mm||94 mm||77 mm||536 g||290||Y||Apr 2019||999|
|9.||Panasonic G9||137 mm||97 mm||92 mm||658 g||400||Y||Nov 2017||1,699|
|10.||Panasonic GH5||139 mm||98 mm||87 mm||725 g||410||Y||Jan 2017||1,999|
|11.||Samsung NX1||139 mm||102 mm||66 mm||550 g||500||Y||Sep 2014||1,499|
|12.||Sony A7C||124 mm||71 mm||60 mm||509 g||740||Y||Sep 2020||1,799|
|13.||Sony A7 III||127 mm||96 mm||74 mm||650 g||610||Y||Feb 2018||1,999|
|14.||Sony A7 II||127 mm||96 mm||60 mm||599 g||350||Y||Nov 2014||1,999|
|15.||Sony A7S||127 mm||94 mm||48 mm||489 g||380||Y||Apr 2014||2,499|
|16.||Sony A7R||127 mm||94 mm||48 mm||465 g||340||Y||Oct 2013||2,299|
|Notes: Measurements and pricing do not include easily detachable parts, such as add-on or interchangeable lenses or optional viewfinders.|
Any camera decision will obviously take relative prices into account. The retail prices at the time of the camera’s release place the model in the market relative to other models in the producer’s line-up and the competition. The A7 was somewhat cheaper (by 6 percent) than the E-M1 III 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.
The size of the sensor inside a digital camera is one of the key determinants of image quality. A large sensor will tend to have larger individual pixels that provide better low-light sensitivity, wider dynamic range, and richer color-depth than smaller pixel-units 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 are more costly to manufacture and tend to 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 a full frame sensor. The sensor area in the A7 is 280 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 offers a 3:2 aspect.
Technology-wise, both cameras are equipped with CMOS (Complementary Metal–Oxide–Semiconductor) sensors.
With 24MP, the A7 offers a higher resolution than the E-M1 III (20.2MP), but the A7 nevertheless has larger individual pixels (pixel pitch of 5.97μm versus 3.34μm for the E-M1 III) due to its larger sensor. However, the E-M1 III is a much more recent model (by 6 years and 3 months) than the A7, and its sensor will 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 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A7 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, 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 are ISO 100 to ISO 25600, with the possibility to increase the ISO range to 50-51200.
For many cameras, data on sensor performance has been reported by DXO Mark. 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||Full Frame||24.0||6000||4000||1080/60p||24.8||14.2||2248||90|
|4.||Nikon Z6 II||Full Frame||24.3||6048||4024||4K/60p||..||..||..||..|
|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.||Panasonic G90||Four Thirds||20.2||5184||3888||4K/30p||..||..||..||..|
|9.||Panasonic G9||Four Thirds||20.2||5184||3888||4K/60p||..||..||..||..|
|10.||Panasonic GH5||Four Thirds||20.2||5184||3888||4K/60p||23.9||13.0||807||77|
|12.||Sony A7C||Full Frame||24.0||6000||4000||4K/30p||25.0||14.7||3407||95|
|13.||Sony A7 III||Full Frame||24.0||6000||4000||4K/30p||25.0||14.7||3730||96|
|14.||Sony A7 II||Full Frame||24.0||6000||4000||1080/60p||24.9||13.6||2449||90|
|15.||Sony A7S||Full Frame||12.0||4240||2832||1080/60p||23.9||13.2||3702||87|
|16.||Sony A7R||Full Frame||36.2||7360||4912||1080/60p||25.6||14.1||2746||95|
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, but the E-M1 III provides a higher video resolution than the A7. It can shoot video footage at 4K/30p, while the Sony is limited to 1080/60p.
Apart from body and sensor, cameras can and do differ across a range of features. The two cameras under review are similar with respect to both having an electronic viewfinder. However, the one in the A7 offers a slightly higher resolution than the one in the E-M1 III (2400k vs 2360k dots). The table below summarizes some of the other core capabilities of the Olympus E-M1 III and Sony A7 in connection with corresponding information for a sample of similar cameras.
|1.||Olympus E-M1 III||2360||n||3.0||1037||swivel||Y||1/8000s||18.0||n||Y|
|4.||Nikon Z6 II||3690||Y||3.2||2100||tilting||Y||1/8000s||14.0||n||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|
|13.||Sony A7 III||2359||n||3.0||922||tilting||Y||1/8000s||10.0||n||Y|
|14.||Sony A7 II||2400||n||3.0||1230||tilting||n||1/8000s||5.0||n||Y|
One feature that differentiates the E-M1 III and the A7 is in-body image stabilization (IBIS). The E-M1 III reduces the risk of handshake-induced blur with all attached lenses, while the A7 offers no blur reduction with lenses that themselves do not provide optical image stabilization.The E-M1 III has an articulated LCD that can be turned to be front-facing. This characteristic will be appreciated by vloggers and photographers who are interested in snapping selfies. In contrast, the A7 does not have a selfie-screen.
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, the E-M1 III is one of those camera that have an additional 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 has 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 uses SDXC or Memory Stick PRO Duo cards. The E-M1 III features dual card slots, which can be very useful in case a memory card fails. In contrast, the A7 only has one slot. The E-M1 III supports UHS-II cards (on its first slot), while the A7 can use UHS-I cards.
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 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|
|4.||Nikon Z6 II||Y||stereo||mono||Y||Y||micro||3.2||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||-||-|
|13.||Sony A7 III||Y||stereo||mono||Y||Y||micro||3.1||Y||Y||Y|
|14.||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) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.
The E-M1 III is a recent model that features in the current product line-up of Olympus. In contrast, the A7 has been discontinued (but can be found pre-owned on eBay). As a replacement in the same line of cameras, the A7 was succeeded by the Sony A7 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 conclusions can be drawn? Is the Olympus E-M1 III better than the Sony A7 or vice versa? The listing below highlights the relative strengths of the two models.
Advantages of 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.
- Better video: Provides higher definition movie capture (4K/30p vs 1080/60p).
- Larger viewfinder image: Features a viewfinder with a higher magnification (0.83x vs 0.71x).
- More flexible LCD: Has a 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.
- More selfie-friendly: Has an articulated screen that can be turned to be front-facing.
- Faster burst: Shoots at higher frequency (18 vs 5 flaps/sec) to capture the decisive moment.
- Less disturbing: Has an electronic shutter option for completely silent shooting.
- Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
- Longer lasting: Can take more shots (420 versus 340) on a single battery charge.
- Sharper images: Has hand-shake reducing image stabilization built-in.
- Faster data transfer: Supports a more advanced USB protocol (3.1 vs 2.0).
- Easier wireless transfer: Supports Bluetooth for image sharing without cables.
- Better studio light control: Has a PC Sync socket to connect to professional strobe lights.
- Greater peace of mind: Features a second card slot as a backup in case of memory card failure.
- Faster buffer clearing: Supports a more advanced SD data transfer standard (UHS-II vs UHS-I).
- More modern: Reflects 6 years and 3 months of technical progress since the A7 launch.
Reasons to prefer the Sony Alpha A7:
- 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.
- More detailed LCD: Has a higher resolution rear screen (1230k vs 1037k dots).
- Less heavy: Has a lower weight (by 106g or 18 percent) and is thus easier to take along.
- Easier device pairing: Supports NFC for fast wireless image transfer over short distances.
- More heavily discounted: Has been around for much longer (launched in October 2013).
If the number of relative strengths (bullet points above) is taken as a guide, the E-M1 III is the clear winner of the match-up (18 : 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 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 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 technical specifications can provide a useful overview of the capabilities of different cameras, it remains incomplete and does no justice, for example, to the way the E-M1 III or the A7 perform in practice. 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 hands-on reviews by experts are important. The following table reports the overall ratings of the cameras as published by some of the major 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||5/5||+ +||80/100||5/5||5/5||Oct 2013||1,699|
|3.||Fujifilm X-H1||..||+||86/100||4.5/5||4.5/5||Feb 2018||1,899|
|4.||Nikon Z6 II||4.5/5||..||89/100||4.5/5||4.5/5||Oct 2020||1,999|
|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.||Panasonic G90||4.5/5||+||83/100||4.5/5||4.5/5||Apr 2019||999|
|9.||Panasonic G9||..||+ +||85/100||5/5||5/5||Nov 2017||1,699|
|10.||Panasonic GH5||4.5/5||+ +||85/100||4.5/5||5/5||Jan 2017||1,999|
|11.||Samsung NX1||5/5||..||87/100||5/5||5/5||Sep 2014||1,499|
|12.||Sony A7C||3.5/5||..||86/100||4/5||4/5||Sep 2020||1,799|
|13.||Sony A7 III||..||+ +||89/100||5/5||5/5||Feb 2018||1,999|
|14.||Sony A7 II||5/5||+||82/100||4.5/5||5/5||Nov 2014||1,999|
|15.||Sony A7S||4/5||..||86/100||4.5/5||5/5||Apr 2014||2,499|
|16.||Sony A7R||5/5||+ +||82/100||4.5/5||5/5||Oct 2013||2,299|
|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. 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 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
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|
|Camera Type||Mirrorless system camera||Mirrorless system camera|
|Camera Lens||Micro Four Thirds lenses||Sony E mount lenses|
|Launch Date||February 2020||October 2013|
|Launch Price||USD 1,799||USD 1,699|
|Sensor Specs||Olympus E-M1 III||Sony A7|
|Sensor Format||Four Thirds Sensor||Full Frame Sensor|
|Sensor Size||17.3 x 13.0 mm||35.8 x 23.9 mm|
|Sensor Area||224.9 mm2||855.62 mm2|
|Sensor Diagonal||21.6 mm||43 mm|
|Sensor Resolution||20.2 Megapixels||24 Megapixels|
|Image Resolution||5184 x 3888 pixels||6000 x 4000 pixels|
|Pixel Pitch||3.34 μm||5.97 μm|
|Pixel Density||8.96 MP/cm2||2.80 MP/cm2|
|Moiré control||no AA filter||Anti-Alias filter|
|Movie Capability||4K/30p Video||1080/60p Video|
|ISO Setting||200 - 25,600 ISO||100 - 25,600 ISO|
|ISO Boost||64 - 25,600 ISO||50 - 51,200 ISO|
|Image Processor||TruePic IX||BIONZ X|
|DXO Sensor Quality (score)||..||90|
|DXO Color Depth (bits)||..||24.8|
|DXO Dynamic Range (EV)||..||14.2|
|DXO Low Light (ISO)||..||2248|
|Screen Specs||Olympus E-M1 III||Sony A7|
|Viewfinder Type||Electronic viewfinder||Electronic viewfinder|
|Viewfinder Field of View||100%||100%|
|Viewfinder Resolution||2360k dots||2400k dots|
|LCD Framing||Live View||Live View|
|Rear LCD Size||3.0inch||3.0inch|
|LCD Resolution||1037k dots||1230k dots|
|LCD Attachment||Swivel screen||Tilting screen|
|Touch Input||Touchscreen||no Touchscreen|
|Shooting Specs||Olympus E-M1 III||Sony A7|
|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||5 shutter flaps/s|
|Electronic Shutter||up to 1/32000s||no E-Shutter|
|Time-Lapse Photography||Intervalometer built-in||no Intervalometer|
|Image Stabilization||In-body stabilization||Lens stabilization only|
|Fill Flash||no On-Board Flash||no On-Board Flash|
|Storage Medium||SDXC cards||MS or SDXC cards|
|Second Storage Option||Dual card slots||Single card slot|
|UHS card support||Single UHS-II||UHS-I|
|Connectivity Specs||Olympus E-M1 III||Sony A7|
|Studio Flash||PC Sync socket||no PC Sync|
|USB Connector||USB 3.1||USB 2.0|
|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||no Bluetooth|
|Body Specs||Olympus E-M1 III||Sony A7|
|Environmental Sealing||Weathersealed body||Weathersealed body|
|Battery Life (CIPA)||420 shots per charge||340 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 94 x 48 mm
(5.0 x 3.7 x 1.9 in)
|Camera Weight||580 g (20.5 oz)||474 g (16.7 oz)|
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