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Sony A7 versus Olympus E-M1

The Sony Alpha A7 and the Olympus OM-D E-M1 are two enthusiast cameras that were revealed to the public, respectively, in October 2013 and September 2013. Both the A7 and the E-M1 are mirrorless interchangeable lens cameras that are based on a full frame (A7) and a Four Thirds (E-M1) sensor. The Sony has a resolution of 24 megapixel, whereas the Olympus provides 15.9 MP. Read on to find out how these two cameras compare with respect to their size, their sensors, their features, and their reception by expert reviewers.

Body comparison: Sony A7 vs Olympus E-M1

An illustration of the physical size and weight of the Sony A7 and the Olympus E-M1 is provided in the side-by-side display below. Three consecutive perspectives from the front, the top, and the back are presented. All size dimensions are rounded to the nearest millimeter. If you prefer, you can also use the toggle button to switch to a comparison in percentage terms (in this case, the camera on the left side – the A7 – represents the basis for the calculations across all the size and weight measures).

Compare Sony A7 vs Olympus E-M1
A7 versus E-M1 top view
A7 and E-M1 rear side
Body view (A7 on the left)

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Olympus E-M1 is somewhat larger (2 percent) than the Sony A7. Moreover, the E-M1 is markedly heavier (5 percent) than the A7. 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 (A7) and the Micro Four Thirds Lens Catalog (E-M1). 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 A7 gets 340 shots out of its NP-FW50 battery, while the E-M1 can take 350 images on a single charge of its BLN-1 power pack.

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 camera 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 A7 (⇒ rgt) 127 mm 94 mm 48 mm 474 g 340 YES 2013 1,699discont. check
Olympus E-M1 (⇒ lft) 130 mm 94 mm 63 mm 497 g 350 YES 2013 1,399discont. check
Nikon D610 (⇒ lft | rgt) 141 mm 113 mm 82 mm 850 g 900 YES 2013 1,999 latest check
Olympus E-M1 II (⇒ lft | rgt) 134 mm 91 mm 67 mm 574 g 440 YES 2016 1,999 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-M10 (⇒ lft | rgt) 119 mm 82 mm 46 mm 396 g 320 no 2014 699discont. check
Olympus E-P5 (⇒ lft | rgt) 122 mm 69 mm 37 mm 420 g 330 no 2013 999discont. check
Olympus E-M5 (⇒ lft | rgt) 122 mm 89 mm 43 mm 425 g 360 YES 2012 1,299discont. check
Panasonic GH4 (⇒ lft | rgt) 133 mm 93 mm 84 mm 560 g 500 YES 2014 1,499discont. 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 A7 II (⇒ lft | rgt) 127 mm 96 mm 60 mm 599 g 350 YES 2014 1,999discont. check
Sony A7S (⇒ lft | rgt) 127 mm 94 mm 48 mm 489 g 380 YES 2014 2,499discont. check
Sony A5100 (⇒ lft | rgt) 110 mm 63 mm 36 mm 283 g 400 no 2014 549 latest check
Sony A7R (⇒ lft | rgt) 127 mm 94 mm 48 mm 465 g 340 YES 2013 2,299discont. check
Sony RX1R (⇒ lft | rgt) 113 mm 65 mm 70 mm 482 g 270 no 2013 2,799discont. check
Sony RX1 (⇒ lft | rgt) 113 mm 65 mm 70 mm 482 g 270 no 2012 2,799discont. check

The price is, of course, an important factor in any camera decision. The listed launch prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The E-M1 was launched at a somewhat lower price (by 18 percent) than the A7, which makes it more attractive for photographers on a tight budget. 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: Sony A7 vs Olympus E-M1

The imaging sensor is at the core of digital cameras and its size is one of the main determining factors 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. Furthermore, a large sensor camera will give the photographer more possibilities to use shallow depth-of-field in order to 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 Sony A7 features a full frame sensor and the Olympus E-M1 a Four Thirds sensor. The sensor area in the E-M1 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 A7 has a native 3:2 aspect ratio, while the one in the E-M1 offers a 4:3 aspect.

Sony A7 and Olympus E-M1 sensor measures
Sensor size

With 24MP, the A7 offers a higher resolution than the E-M1 (15.9MP), but the A7 nevertheless has larger individual pixels (pixel pitch of 5.97μm versus 3.76μm for the E-M1) due to its larger sensor. It is noteworthy in this context that the two cameras were released in close succession, so that their sensors are from the same technological generation. Coming back to sensor resolution, it should be mentioned that the E-M1 has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

A7 versus E-M1 MP
Sensor resolution

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. Of the two cameras under review, the A7 provides substantially higher image quality than the E-M1, with an overall score that is 17 points higher. This advantage is based on 1.8 bits higher color depth, 1.5 EV in additional dynamic range, and 1.6 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
Sony A7 (⇒ rgt) Full Frame 24.0 6000 4000 1080/60p 24.8 14.2 2248 90
Olympus E-M1 (⇒ lft) Four Thirds 15.9 4608 3456 1080/30p 23.0 12.7 757 73
Nikon D610 (⇒ lft | rgt) Full Frame 24.2 6016 4016 1080/30p 25.1 14.4 2925 94
Olympus E-M1 II (⇒ lft | rgt) Four Thirds 20.2 5184 3888 4K/30p 23.7 12.8 1312 80
Olympus E-M5 II (⇒ lft | rgt) Four Thirds 15.9 4608 3456 1080/60p 23.0 12.5 842 73
Olympus E-M10 (⇒ lft | rgt) Four Thirds 15.9 4608 3456 1080/30p 22.8 12.3 884 72
Olympus E-P5 (⇒ lft | rgt) Four Thirds 15.9 4608 3456 1080/30p 22.8 12.4 895 72
Olympus E-M5 (⇒ lft | rgt) Four Thirds 15.9 4608 3456 1080/60i 22.8 12.3 826 71
Panasonic GH4 (⇒ lft | rgt) Four Thirds 15.9 4608 3456 4K/30p 23.2 12.8 791 74
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 A7 II (⇒ lft | rgt) Full Frame 24.0 6000 4000 1080/60p 24.9 13.6 2449 90
Sony A7S (⇒ lft | rgt) Full Frame 12.0 4240 2832 1080/60p 23.9 13.2 3702 87
Sony A5100 (⇒ lft | rgt) APS-C 24.0 6000 4000 1080/60p 23.8 12.7 1347 80
Sony A7R (⇒ lft | rgt) Full Frame 36.2 7360 4912 1080/60p 25.6 14.1 2746 95
Sony RX1R (⇒ lft | rgt) Full Frame 24.0 6000 4000 1080/60p 25.0 13.6 2537 91
Sony RX1 (⇒ lft | rgt) Full Frame 24.0 6000 4000 1080/60p 25.1 14.3 2534 93

Many modern cameras are not only capable of taking still images, but can also record movies. Both cameras under consideration are equipped with sensors that have a sufficiently high read-out speed for moving images, but the A7 provides a higher frame rate than the E-M1. It can shoot video footage at 1080/60p, while the Olympus is limited to 1080/30p.

Feature comparison: Sony A7 vs Olympus E-M1

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 A7 offers a slightly higher resolution than the one in the E-M1 (2400k vs 2360k dots). The table below summarizes some of the other core capabilities of the Sony A7 and Olympus E-M1 in connection with corresponding information for a sample of similar 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
Sony A7 (⇒ rgt) 2400 no 3.0 1230 tilting no 8000 5.0 no no
Olympus E-M1 (⇒ lft) 2360 no 3.0 1037 tilting YES 8000 10.0 no YES
Nikon D610 (⇒ lft | rgt) optical YES 3.2 921 fixed no 4000 6.0 12 no
Olympus E-M1 II (⇒ lft | rgt) 2360 no 3.0 1037 swivel YES 8000 18.0 no YES
Olympus E-M5 II (⇒ lft | rgt) 2360 no 3.0 1037 swivel YES 8000 10.0 no YES
Olympus E-M10 (⇒ lft | rgt) 1440 no 3.0 1037 tilting YES 4000 8.0 5.8 YES
Olympus E-P5 (⇒ lft | rgt) no no 3.0 1037 tilting YES 8000 9.0 7 YES
Olympus E-M5 (⇒ lft | rgt) 1440 no 3.0 610 tilting YES 4000 9.0 no YES
Panasonic GH4 (⇒ lft | rgt) 2359 no 3.0 1036 swivel YES 8000 12.0 17 no
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 A7 II (⇒ lft | rgt) 2400 no 3.0 1230 tilting no 8000 5.0 no YES
Sony A7S (⇒ lft | rgt) 2400 no 3.0 921 tilting no 8000 5.0 no no
Sony A5100 (⇒ lft | rgt) no no 3.0 922 tilting YES 4000 6.0 4 no
Sony A7R (⇒ lft | rgt) 2400 no 3.0 1230 tilting no 8000 4.0 no no
Sony RX1R (⇒ lft | rgt) no no 3.0 1229 fixed no 4000 5.0 6 no
Sony RX1 (⇒ lft | rgt) no no 3.0 1229 fixed no 4000 5.0 6 no

Both the A7 and the E-M1 have been discontinued, but can regularly be found used on eBay. The E-M1 was replaced by the Olympus E-M1 II, while the A7 was followed by the Sony A7 II.

Review summary: Sony A7 vs Olympus E-M1

So how do things add up? Is there a clear favorite between the Sony A7 and the Olympus E-M1? A synthesis of the relative strong points of each of the models is listed below.


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Advantages of the Sony Alpha A7:

  • More detail: Offers more megapixels (24 vs 15.9MP) with a 25% higher linear resolution.
  • Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
  • Better image quality: Scores substantially higher (17 points) in the DXO overall assessment.
  • Richer colors: Generates images with noticeably better colors (1.8 bits more color depth).
  • More dynamic range: Captures a larger spectrum of light and dark details (1.5 EV of extra DR).
  • Better low-light sensitivity: Requires less light for good images (1.6 stops ISO advantage).
  • Better video: Provides higher movie framerates (1080/60p versus 1080/30p).
  • More detailed LCD: Has a higher resolution rear screen (1230k vs 1037k dots).

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Reasons to prefer the Olympus OM-D E-M1:

  • Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
  • Fewer buttons to press: Has a touchscreen to facilitate handling and shooting adjustments.
  • Faster burst: Shoots at higher frequency (10 vs 5 flaps/sec) to capture the decisive moment.
  • Sharper images: Has stabilization technology build-in to reduce the impact of hand-shake.
  • More affordable: Was released into a lower priced segment (18 percent cheaper at launch).

If the count of relative strengths (bullet points above) is taken as a measure, the A7 emerges as the winner of the contest (8 : 5 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 before making a decision on a new camera.

A7 08:05 E-M1

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 A7 and the E-M1 in practical situations. 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 following table reports the overall rankings of the cameras as published by some of the major 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
.com
dp
review
.com
ephoto
zine
.com
imaging
resource
.com
photography
blog
.com
Camera
Launch
(year)
Launch
Price
(USD)
Street
Price
(amazon)
Used
Price
(ebay)
Sony A7 (⇒ rgt) HiRec 80/100 Silver 5/5 4.5/5 5/5 2013 1,699discont. check
Olympus E-M1 (⇒ lft) HiRec 84/100 Gold 4.5/5 4.5/5 4.5/5 2013 1,399discont. check
Nikon D610 (⇒ lft | rgt) HiRec 87/100 Gold 4.5/5 4.5/5 4.5/5 2013 1,999 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 E-M5 II (⇒ lft | rgt) HiRec 81/100 Silver 5/5 4.5/5 5/5 2015 1,099 latest check
Olympus E-M10 (⇒ lft | rgt) - 80/100 Gold 5/5 4.5/5 5/5 2014 699discont. check
Olympus E-P5 (⇒ lft | rgt) HiRec 78/100 Silver 4.5/5 4.5/5 5/5 2013 999discont. check
Olympus E-M5 (⇒ lft | rgt) HiRec 80/100 Gold 4.5/5 5/5 5/5 2012 1,299discont. check
Panasonic GH4 (⇒ lft | rgt) HiRec 85/100 Gold 5/5 5/5 5/5 2014 1,499discont. 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 A7 II (⇒ lft | rgt) Rec 82/100 Silver 4.5/5 5/5 5/5 2014 1,999discont. check
Sony A7S (⇒ lft | rgt) - 86/100 Gold 4.5/5 4.5/5 5/5 2014 2,499discont. check
Sony A5100 (⇒ lft | rgt) Rec - 4.5/5 4.5/5 5/5 2014 549 latest check
Sony A7R (⇒ lft | rgt) HiRec 82/100 Gold 4.5/5 5/5 5/5 2013 2,299discont. check
Sony RX1R (⇒ lft | rgt) - - 4/5 reviewed 4.5/5 2013 2,799discont. check
Sony RX1 (⇒ lft | rgt) - 79/100 Gold 4/5 4.5/5 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 camera comparisons

Did this review help to inform your camera decision process? 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. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored. If the camera you are interested in is not available, please contact me, and I will try to add information on that model to the database.

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