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Olympus E-M1 versus Nikon D7100

The Olympus OM-D E-M1 and the Nikon D7100 are two enthusiast cameras that were revealed to the public, respectively, in September 2013 and February 2013. The E-M1 is a mirrorless interchangeable lens camera, while the D7100 is a DSLR. The cameras are based on a Four Thirds (E-M1) and an APS-C sensor. The Olympus has a resolution of 15.9 megapixel, whereas the Nikon provides 24 MP.

Body comparison

The physical size and weight of the Olympus E-M1 and the Nikon D7100 are illustrated 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. 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 – the E-M1 – represents 100 percent across all the size and weight measures).

Olympus E-M1 vs Nikon D7100 front
E-M1 versus D7100 top view
E-M1 and D7100 rear side
Body view (E-M1 on the left)

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Nikon D7100 is considerably larger (19 percent) than the Olympus E-M1. Moreover, the D7100 is substantially heavier (54 percent) than the E-M1. 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 Micro Four Thirds Lens Catalog (E-M1) and the Nikon Lens Catalog (D7100). Mirrorless cameras, such as the Olympus E-M1, have moreover the advantage that they have a relatively short flange to focal plane distance and can thus use many lenses from other systems 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)
Olympus E-M1 (⇒ rgt) 130 mm 94 mm 63 mm 497 g 350 YES 2013 1,399discont. check
Nikon D7100 (⇒ lft) 136 mm 107 mm 76 mm 765 g 950 YES 2013 1,199discont. check
Nikon D7500 (⇒ lft | rgt) 136 mm 104 mm 73 mm 720 g 950 YES 2017 1,299 latest check
Nikon D500 (⇒ lft | rgt) 147 mm 115 mm 81 mm 860 g 1240 YES 2016 1,999 latest check
Nikon D7200 (⇒ lft | rgt) 136 mm 107 mm 76 mm 765 g 1110 YES 2015 1,199discont. check
Nikon D750 (⇒ lft | rgt) 141 mm 113 mm 78 mm 750 g 1230 YES 2014 2,299 latest 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 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-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 G85 (⇒ lft | rgt) 128 mm 89 mm 74 mm 505 g 330 YES 2016 899 latest check
Panasonic GX8 (⇒ lft | rgt) 133 mm 78 mm 63 mm 487 g 330 YES 2015 1,199discont. check
Panasonic GH4 (⇒ lft | rgt) 133 mm 93 mm 84 mm 560 g 500 YES 2014 1,499discont. check
Panasonic GH3 (⇒ lft | rgt) 133 mm 93 mm 82 mm 550 g 540 YES 2012 1,299discont. check

The listed prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The D7100 was launched at a somewhat lower price (by 14 percent) than the E-M1, 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

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. 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 tent to lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Olympus E-M1 features a Four Thirds sensor and the Nikon D7100 an APS-C sensor. The sensor area in the D7100 is 63 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 2.0 and 1.5. The sensor in the E-M1 has a native 4:3 aspect ratio, while the one in the D7100 offers a 3:2 aspect.

Olympus E-M1 and Nikon D7100 sensor measures
Sensor size

With 24MP, the D7100 offers a higher resolution than the E-M1 (15.9MP), but the D7100 nevertheless has larger individual pixels (pixel pitch of 3.91μm versus 3.76μm for the E-M1) due to its larger sensor. However, the E-M1 is a somewhat more recent model (by 6 months) than the D7100, 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 neither of the two cameras has an anti-alias filter installed, so they are able to capture all the detail the sensor resolves.

E-M1 versus D7100 MP
Sensor resolution

Consistent information on actual sensor performance is available from DXO Mark for most cameras. 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 consideration, the D7100 has a markedly higher DXO score than the E-M1 (overall score 10 points higher), which will translate into better image quality. The advantage is based on 1.2 bits higher color depth, 1 EV in additional dynamic range, and 0.7 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
Olympus E-M1 (⇒ rgt) Four Thirds 15.9 4608 3456 1080/30p 23.0 12.7 757 73
Nikon D7100 (⇒ lft) APS-C 24.0 6000 4000 1080/60p 24.2 13.7 1256 83
Nikon D7500 (⇒ lft | rgt) APS-C 20.7 5568 3712 4K/30p 24.3 14.0 1483 86
Nikon D500 (⇒ lft | rgt) APS-C 20.7 5568 3712 4K/30p 24.0 14.0 1324 83
Nikon D7200 (⇒ lft | rgt) APS-C 24.0 6000 4000 1080/60p 24.5 14.6 1333 87
Nikon D750 (⇒ lft | rgt) Full Frame 24.2 6016 4016 1080/60p 24.8 14.5 2956 93
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 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-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 G85 (⇒ lft | rgt) Four Thirds 15.8 4592 3448 4K/30p 22.8 12.5 656 71
Panasonic GX8 (⇒ lft | rgt) Four Thirds 20.2 5184 3888 4K/30p 23.5 12.6 806 75
Panasonic GH4 (⇒ lft | rgt) Four Thirds 15.9 4608 3456 4K/30p 23.2 12.8 791 74
Panasonic GH3 (⇒ lft | rgt) Four Thirds 15.9 4608 3456 1080/60p 22.7 12.4 812 71

Many modern cameras cannot only take still pictures, but also record videos. Both cameras under consideration have a sensor with sufficiently fast read-out times for moving pictures, but the D7100 provides a faster frame rate than the E-M1. It can shoot movie footage at 1080/60p, while the Olympus is limited to 1080/30p.

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. For example, the E-M1 has an electronic viewfinder (2360k dots), while the D7100 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 table below summarizes some of the other core capabilities of the Olympus E-M1 and Nikon D7100 in connection with corresponding information for a sample of similar 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
Olympus E-M1 (⇒ rgt) 2360 no 3.0 1037 tilting YES 8000 10.0 no YES
Nikon D7100 (⇒ lft) optical YES 3.2 1229 fixed no 8000 6.0 12 no
Nikon D7500 (⇒ lft | rgt) optical YES 3.2 922 tilting YES 8000 8.0 12 no
Nikon D500 (⇒ lft | rgt) optical YES 3.2 2359 tilting YES 8000 10.0 no no
Nikon D7200 (⇒ lft | rgt) optical YES 3.2 1229 fixed no 8000 6.0 12 no
Nikon D750 (⇒ lft | rgt) optical YES 3.2 1229 tilting no 4000 6.0 12 no
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 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-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 G85 (⇒ lft | rgt) 2360 no 3.0 1040 swivel YES 4000 9.0 6.2 YES
Panasonic GX8 (⇒ lft | rgt) 2360 no 3.0 1040 swivel YES 8000 10.0 no YES
Panasonic GH4 (⇒ lft | rgt) 2359 no 3.0 1036 swivel YES 8000 12.0 17 no
Panasonic GH3 (⇒ lft | rgt) 1746 no 3.0 614 swivel YES 4000 6.0 12 no

Both the E-M1 and the D7100 have been discontinued, but can regularly be found used on ebay. The D7100 was replaced by the Nikon D7200, while the E-M1 was followed by the Olympus E-M1 II.

Summary

So how do things add up? Is the Olympus E-M1 better than the Nikon D7100 or vice versa? Below is a summary of the relative strengths of each of the two contestants.


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

  • More framing info: Has an electronic viewfinder that displays shooting data.
  • More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
  • Fewer buttons to press: Is equipped with a touch-sensitive rear screen to facilitate handling.
  • Faster burst: Shoots at higher frequency (10 vs 6 flaps/sec) to capture the decisive moment.
  • More compact: Is smaller (130x94mm vs 136x107mm) and thus needs less room in the bag.
  • Less heavy: Is lighter (by 268g or 35 percent) and hence easier to carry around.
  • More legacy lens friendly: Can take a broad range of non-native lenses via adapters.
  • Sharper images: Has hand-shake reducing image stabilization build-in.
  • More modern: Is somewhat more recent (announced 6 months after the D7100).

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Advantages of the Nikon D7100:

  • More detail: Has more megapixels (24 vs 15.9MP), which boosts linear resolution by 25%.
  • Better image quality: Scores markedly higher (10 points) in the DXO overall evaluation.
  • Richer colors: Generates noticeably more natural colors (1.2 bits more color depth).
  • More dynamic range: Captures a broader range of light and dark details (1 EV of extra DR).
  • Better low-light sensitivity: Can shoot in dim conditions (0.7 stops ISO advantage).
  • Better video: Provides higher movie framerates (1080/60p vs 1080/30p).
  • Brighter framing: Features an optical viewfinder for clear, lag-free composition.
  • Easier setting verification: Has a control panel on top to check shooting parameters.
  • Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
  • More detailed LCD: Has a higher resolution rear screen (1229k vs 1037k dots).
  • Longer lasting: Gets more shots (950 versus 350) out of a single battery charge.
  • Easier fill-in: Has a small integrated flash to brighten shadows of backlit subjects.
  • More affordable: Was released into a lower priced segment (14 percent cheaper at launch).
  • More heavily discounted: Has been on the market for longer (launched in February 2013).

If the count of individual advantages (bullet points above) is taken as a guide, the D7100 is the clear winner of the contest (14 : 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.

E-M1 09:14 D7100

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 or the D7100 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 why expert reviews are important. 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)
Olympus E-M1 (⇒ rgt) HiRec 84/100 Gold 4.5/5 4.5/5 4.5/5 2013 1,399discont. check
Nikon D7100 (⇒ lft) HiRec 85/100 Gold 4.5/5 5/5 4.5/5 2013 1,199discont. check
Nikon D7500 (⇒ lft | rgt) HiRec 86/100 Silver 5/5 4.5/5 4.5/5 2017 1,299 latest check
Nikon D500 (⇒ lft | rgt) HiRec 91/100 Gold 4.5/5 5/5 5/5 2016 1,999 latest check
Nikon D7200 (⇒ lft | rgt) HiRec 84/100 Silver 4.5/5 4/5 4.5/5 2015 1,199discont. check
Nikon D750 (⇒ lft | rgt) HiRec 90/100 Gold 4.5/5 5/5 4.5/5 2014 2,299 latest 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 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-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 G85 (⇒ lft | rgt) HiRec 84/100 Gold 5/5 4.5/5 4.5/5 2016 899 latest check
Panasonic GX8 (⇒ lft | rgt) Rec 82/100 Silver 4.5/5 5/5 4.5/5 2015 1,199discont. check
Panasonic GH4 (⇒ lft | rgt) HiRec 85/100 Gold 5/5 5/5 5/5 2014 1,499discont. check
Panasonic GH3 (⇒ lft | rgt) HiRec 79/100 Gold 4.5/5 5/5 4.5/5 2012 1,299discont. check

The above review scores should be interpreted with care, though. The ratings are only valid when refering to cameras in the same category and of the same age. Hence, a score should always be seen in the context of the camera's market launch date and its price, and comparing ratings of very distinct cameras or ones that are far apart in terms of their release date have little meaning. Also, please note that some of the review sites have changed their methodology and reporting over time.

Other comparisons

If you would like to see a different side-by-side camera review, just make a corresponding selection in the search boxes below. 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 add information on that model to the database.

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