Nikon D5100 vs Olympus E-M5

The Nikon D5100 and the Olympus OM-D E-M5 are two digital cameras that were revealed to the public, respectively, in April 2011 and February 2012. The D5100 is a DSLR, while the E-M5 is a mirrorless interchangeable lens camera. The cameras are based on an APS-C (D5100) and a Four Thirds (E-M5) sensor. The Nikon has a resolution of 16.1 megapixels, whereas the Olympus provides 15.9 MP.

Below is an overview of the main specs of the two cameras as a starting point for the comparison.

Headline Specifications

Nikon D5100		Olympus E-M5
Digital single lens reflex		Mirrorless system camera
Nikon F mount lenses		Micro Four Thirds lenses
16.1 MP – APS-C sensor		15.9 MP – Four Thirds sensor
1080/30p Video		1080/60i Video
ISO 100-6,400 (100 - 25,600)		ISO 200-25,600
Optical viewfinder		Electronic viewfinder (1440k dots)
3.0" LCD – 921k dots		3.0" LCD – 610k dots
Swivel screen (not touch-sensitive)		Tilting touchscreen
4 shutter flaps per second		9 shutter flaps per second
Lens stabilization only		In-body stabilization
not weather sealed		Weathersealed body
660 shots per battery charge		360 shots per battery charge
128 x 97 x 79 mm, 560 g		122 x 89 x 43 mm, 425 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Nikon D5100 and the Olympus OM-D E-M5? 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.

Body comparison

The side-by-side display below illustrates the physical size and weight of the Nikon D5100 and the Olympus E-M5. The two cameras are presented according to their relative size. Three successive views from the front, the top, and the rear are shown. All size dimensions are rounded to the nearest millimeter.

The E-M5 can be obtained in two different colors (black, silver), while the D5100 is only available in black.

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Olympus E-M5 is notably smaller (13 percent) than the Nikon D5100. Moreover, the E-M5 is markedly lighter (24 percent) than the D5100. It is noteworthy in this context that the E-M5 is splash and dust-proof, while the D5100 does not feature any corresponding weather-sealing.

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 Nikon Lens Catalog (D5100) and the Micro Four Thirds Lens Catalog (E-M5). Mirrorless cameras, such as the E-M5, have moreover the advantage that they can use many lenses from other systems via adapters, as they have a relatively short flange to focal plane distance.

Concerning battery life, the D5100 gets 660 shots out of its Nikon EN-EL14 battery, while the E-M5 can take 360 images on a single charge of its Olympus BLN-1 power pack.

The adjacent table lists the principal physical characteristics of the two cameras alongside a wider set of alternatives. If you would like to visualize and compare a different camera combination, you can navigate to the CAM-parator app and make your selection from a broad list of cameras there.

Body Specifications

		Camera Model	Camera Width	Camera Height	Camera Depth	Camera Weight	Battery Life	Weather Sealing	Camera Launch	Launch Price (USD)	Street Price
1.		Nikon D5100	128 mm	97 mm	79 mm	560 g	660	n	Apr 2011	749	ebay.com
2.		Olympus E-M5	122 mm	89 mm	43 mm	425 g	360	Y	Feb 2012	1,299	ebay.com
3.		Canon T2i	129 mm	98 mm	62 mm	530 g	440	n	Feb 2010	699	ebay.com
4.		Nikon D3100	124 mm	96 mm	75 mm	505 g	550	n	Aug 2010	599	ebay.com
5.		Nikon D3200	125 mm	96 mm	77 mm	505 g	540	n	Apr 2012	599	ebay.com
6.		Nikon D5000	127 mm	104 mm	80 mm	590 g	510	n	Apr 2009	749	ebay.com
7.		Nikon D5200	129 mm	98 mm	78 mm	555 g	500	n	Nov 2012	749	ebay.com
8.		Nikon D5300	125 mm	98 mm	76 mm	480 g	600	n	Oct 2013	799	ebay.com
9.		Nikon D5500	124 mm	97 mm	70 mm	470 g	820	n	Jan 2015	899	ebay.com
10.		Nikon D5600	124 mm	97 mm	70 mm	465 g	970	n	Nov 2016	699	ebay.com
11.		Nikon D7000	132 mm	105 mm	77 mm	780 g	1050	Y	Sep 2010	1,499	ebay.com
12.		Olympus E-M1	130 mm	94 mm	63 mm	497 g	350	Y	Sep 2013	1,399	ebay.com
13.		Olympus E-M5 II	124 mm	85 mm	45 mm	469 g	310	Y	Feb 2015	1,099	ebay.com
14.		Olympus E-P5	122 mm	69 mm	37 mm	420 g	330	n	May 2013	999	ebay.com
15.		Olympus PEN-F	125 mm	72 mm	37 mm	427 g	330	n	Jan 2016	1,199	ebay.com
16.		Panasonic GX7	123 mm	71 mm	55 mm	402 g	350	n	Aug 2013	999	ebay.com
17.		Sony NEX-5N	111 mm	59 mm	38 mm	269 g	460	n	Aug 2011	699	ebay.com
Note: Measurements and pricing do not include easily detachable parts, such as add-on or interchangeable lenses or optional viewfinders.
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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 D5100 was launched at a markedly lower price (by 42 percent) than the E-M5, 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.

Sensor comparison

The size of the imaging sensor is a crucial determinant 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 Nikon D5100 features an APS-C sensor and the Olympus E-M5 a Four Thirds sensor. The sensor area in the E-M5 is 39 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.5 and 2.0. The sensor in the D5100 has a native 3:2 aspect ratio, while the one in the E-M5 offers a 4:3 aspect.

With 16.1MP, the D5100 offers a slightly higher resolution than the E-M5 (15.9MP), but the D5100 nevertheless has larger individual pixels (pixel pitch of 4.80μm versus 3.76μm for the E-M5) due to its larger sensor. However, the E-M5 is a somewhat more recent model (by 10 months) than the D5100, and its sensor might have benefitted from technological advances during this time that enhance the light gathering capacity of its pixels.

The Nikon D5100 has a native sensitivity range from ISO 100 to ISO 6400, which can be extended to ISO 100-25600. The corresponding ISO settings for the Olympus OM-D E-M5 are ISO 200 to ISO 25600 (no boost).

Technology-wise, both cameras are equipped with CMOS (Complementary Metal–Oxide–Semiconductor) sensors. Both cameras use a Bayer filter for capturing RGB colors on a square grid of photosensors. This arrangement is found in most digital cameras.

Consistent information on actual sensor performance is available from DXO Mark for many 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 review, the D5100 has a notably higher overall DXO score than the E-M5 (overall score 9 points higher), which gives it an advantage in terms of imaging quality. This advantage is based on 0.7 bits higher color depth, 1.3 EV in additional dynamic range, and 0.5 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 Model	Sensor Class	Resolution (MP)	Horiz. Pixels	Vert. Pixels	Video Format	DXO Portrait	DXO Landscape	DXO Sports	DXO Overall
1.		Nikon D5100	APS-C	16.1	4928	3264	1080/30p	23.5	13.6	1183	80
2.		Olympus E-M5	Four Thirds	15.9	4608	3456	1080/60i	22.8	12.3	826	71
3.		Canon T2i	APS-C	17.9	5184	3456	1080/30p	22.1	11.5	784	66
4.		Nikon D3100	APS-C	14.2	4608	3072	1080/24p	22.5	11.3	919	67
5.		Nikon D3200	APS-C	24.1	6016	4000	1080/30p	24.1	13.2	1131	81
6.		Nikon D5000	APS-C	12.2	4288	2848	720/24p	22.7	12.5	868	72
7.		Nikon D5200	APS-C	24.0	6000	4000	1080/60i	24.2	13.9	1284	84
8.		Nikon D5300	APS-C	24.0	6000	4000	1080/60p	24.0	13.9	1338	83
9.		Nikon D5500	APS-C	24.0	6000	4000	1080/60p	24.1	14.0	1438	84
10.		Nikon D5600	APS-C	24.0	6000	4000	1080/60p	24.1	14.0	1306	84
11.		Nikon D7000	APS-C	16.1	4928	3264	1080/24p	23.5	13.9	1167	80
12.		Olympus E-M1	Four Thirds	15.9	4608	3456	1080/30p	23.0	12.7	757	73
13.		Olympus E-M5 II	Four Thirds	15.9	4608	3456	1080/60p	23.0	12.5	842	73
14.		Olympus E-P5	Four Thirds	15.9	4608	3456	1080/30p	22.8	12.4	895	72
15.		Olympus PEN-F	Four Thirds	20.2	5184	3888	1080/60p	23.1	12.4	894	74
16.		Panasonic GX7	Four Thirds	15.8	4592	3448	1080/60p	22.6	12.2	718	70
17.		Sony NEX-5N	APS-C	16.0	4912	3264	1080/60i	23.6	12.7	1079	77

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 E-M5 provides a faster frame rate than the D5100. It can shoot movie footage at 1080/60i, while the Nikon is limited to 1080/30p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a range of features. For example, the E-M5 has an electronic viewfinder (1440k dots), while the D5100 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 viewfinder in the E-M5 offers a wider field of view (100%) than the one in the D5100 (95%), so that a larger proportion of the captured image is visible in the finder. In addition, the viewfinder of the E-M5 has a higher magnification (0.58x vs 0.51x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The table below summarizes some of the other core capabilities of the Nikon D5100 and Olympus E-M5 in connection with corresponding information for a sample of similar cameras.

Core Features

		Camera Model	Viewfinder (Type or 000 dots)	Control Panel (yes/no)	LCD Specifications (inch/000 dots)	LCD Attach- ment	Touch Screen (yes/no)	Max Shutter Speed *	Max Shutter Flaps *	Built-in Flash (yes/no)	Built-in Image Stab
1.		Nikon D5100	optical	n	3.0 / 921	swivel	n	1/4000s	4.0/s	Y	n
2.		Olympus E-M5	1440	n	3.0 / 610	tilting	Y	1/4000s	9.0/s	n	Y
3.		Canon T2i	optical	n	3.0 / 1040	fixed	n	1/4000s	3.7/s	Y	n
4.		Nikon D3100	optical	n	3.0 / 230	fixed	n	1/4000s	3.0/s	Y	n
5.		Nikon D3200	optical	n	3.0 / 921	fixed	n	1/4000s	4.0/s	Y	n
6.		Nikon D5000	optical	n	2.7 / 230	full-flex	n	1/4000s	4.0/s	Y	n
7.		Nikon D5200	optical	n	3.0 / 921	swivel	n	1/4000s	5.0/s	Y	n
8.		Nikon D5300	optical	n	3.2 / 1037	swivel	n	1/4000s	5.0/s	Y	n
9.		Nikon D5500	optical	n	3.2 / 1037	swivel	Y	1/4000s	5.0/s	Y	n
10.		Nikon D5600	optical	n	3.2 / 1037	swivel	Y	1/4000s	5.0/s	Y	n
11.		Nikon D7000	optical	Y	3.0 / 921	fixed	n	1/8000s	6.0/s	Y	n
12.		Olympus E-M1	2360	n	3.0 / 1037	tilting	Y	1/8000s	10.0/s	n	Y
13.		Olympus E-M5 II	2360	n	3.0 / 1037	swivel	Y	1/8000s	10.0/s	n	Y
14.		Olympus E-P5	optional	n	3.0 / 1037	tilting	Y	1/8000s	9.0/s	Y	Y
15.		Olympus PEN-F	2360	n	3.0 / 1037	swivel	Y	1/8000s	10.0/s	n	Y
16.		Panasonic GX7	2760	n	3.0 / 1040	tilting	Y	1/8000s	5.0/s	Y	Y
17.		Sony NEX-5N	optional	n	3.0 / 920	tilting	Y	1/4000s	10.0/s	n	n
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One difference between the cameras concerns the presence of an on-board flash. The D5100 has one, while the E-M5 does not. While the built-in flash of the D5100 is not very powerful, it can at times be useful as a fill-in light.

The Nikon D5100 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.

Concerning the storage of imaging data, both the D5100 and the E-M5 write their files to SDXC cards. Both cameras can use UHS-I cards, which provide for Ultra High Speed data transfer of up to 104 MB/s.

Connectivity comparison

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 Nikon D5100 and Olympus OM-D E-M5 and, in particular, the interfaces the cameras (and selected comparators) provide for accessory control and data transfer.

Input-Output Connections

		Camera Model	Hotshoe Port	Internal Mic / Speaker	Microphone Port	Headphone Port	HDMI Port	USB Port	WiFi Support	NFC Support	Bluetooth Support
1.		Nikon D5100	Y	mono / mono	Y	-	mini	2.0	-	-	-
2.		Olympus E-M5	Y	stereo / mono	-	-	mini	2.0	-	-	-
3.		Canon T2i	Y	stereo / -	Y	-	mini	2.0	-	-	-
4.		Nikon D3100	Y	mono / mono	-	-	mini	2.0	-	-	-
5.		Nikon D3200	Y	mono / mono	Y	-	mini	2.0	-	-	-
6.		Nikon D5000	Y	mono / mono	-	-	mini	2.0	-	-	-
7.		Nikon D5200	Y	stereo / mono	Y	-	mini	2.0	-	-	-
8.		Nikon D5300	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
9.		Nikon D5500	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
10.		Nikon D5600	Y	stereo / mono	Y	-	mini	2.0	Y	Y	Y
11.		Nikon D7000	Y	mono / mono	Y	-	mini	2.0	-	-	-
12.		Olympus E-M1	Y	stereo / mono	Y	-	micro	2.0	Y	-	-
13.		Olympus E-M5 II	Y	stereo / mono	Y	-	micro	2.0	Y	-	-
14.		Olympus E-P5	Y	stereo / mono	-	-	micro	2.0	Y	-	-
15.		Olympus PEN-F	Y	stereo / mono	-	-	micro	2.0	Y	-	-
16.		Panasonic GX7	Y	stereo / mono	-	-	mini	2.0	Y	Y	-
17.		Sony NEX-5N	Y	stereo / mono	-	-	mini	2.0	-	-	-

It is notable that the D5100 has a microphone port, which is missing on the E-M5. Such an external microphone input can help to substantially improve the quality of audio recordings when a good external microphone is used.

Both the D5100 and the E-M5 have been discontinued, but can regularly be found used on ebay. The D5100 was replaced by the Nikon D5200, while the E-M5 was followed by the Olympus E-M5 II. Further information on the features and operation of the D5100 and E-M5 can be found, respectively, in the Nikon D5100 Manual (free pdf) or the online Olympus E-M5 Manual.

Review summary

So what conclusions can be drawn? Which of the two cameras – the Nikon D5100 or the Olympus E-M5 – has the upper hand? Is one clearly better than the other? A synthesis of the relative strong points of each of the models is listed below.

Advantages of the Nikon D5100:

• Better image quality: Scores markedly higher (9 points) in the DXO overall assessment.
• More dynamic range: Captures a larger spectrum of light and dark details (1.3 EV of extra DR).
• Better low-light sensitivity: Requires less light for good images (0.5 stops ISO advantage).
• Better sound: Can connect to an external microphone for higher quality sound recording.
• Brighter framing: Features an optical viewfinder for clear, lag-free composition.
• More detailed LCD: Has a higher resolution rear screen (921k vs 610k 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.
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• Longer lasting: Can take more shots (660 versus 360) on a single battery charge.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• More affordable: Was introduced into a lower priced category (42 percent cheaper at launch).
• More heavily discounted: Has been on the market for longer (launched in April 2011).

Reasons to prefer the Olympus OM-D E-M5:

• Better video: Provides higher movie framerates (1080/60i versus 1080/30p).
• More framing info: Has an electronic viewfinder that displays shooting data.
• More complete view: Has a viewfinder with a larger field of view (100% vs 95%).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.58x vs 0.51x).
• Fewer buttons to press: Has a touchscreen to facilitate handling and shooting adjustments.
• Faster burst: Shoots at higher frequency (9 vs 4 flaps/sec) to capture the decisive moment.
• More compact: Is smaller (122x89mm vs 128x97mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 135g or 24 percent) and is thus easier to take along.
• Better sealing: Is splash and dust sealed for shooting in inclement weather conditions.
• Sharper images: Has stabilization technology built-in to reduce the impact of hand-shake.
• More legacy lens friendly: Can use many non-native lenses via adapters.
• More modern: Was introduced somewhat (10 months) more recently.

If the number of relative strengths (bullet points above) is taken as a guide, the D5100 comes out slightly ahead of the E-M5 (13 : 12 points). However, the pertinence of the various camera strengths will differ across photographers, so that you might want to weigh individual camera traits according to their importance for your own imaging needs before making a camera decision. 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 Nikon D5100 and the Olympus E-M5 place the cameras among the top in their class? Find out in the latest Best DSLR Camera and Best Mirrorless Interchangeable Lens Camera listings 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 D5100 and the E-M5 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.

Expert reviews

This is why expert reviews are important. The adjacent summary-table relays the overall verdicts of several of the most popular camera review sites (amateurphotographer [AP], cameralabs [CL], digitalcameraworld [DCW], 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.

Expert Camera Reviews

		Camera   Model	AP   score	CL   score	DCW   score	DPR   score	EPZ   score	PB   score	Camera Launch	Launch Price (USD)	Street Price
1.		Nikon D5100	5/5	+ +	..	76/100	4.5/5	4.5/5	Apr 2011	749	ebay.com
2.		Olympus E-M5	4/5	+ +	..	80/100	4.5/5	5/5	Feb 2012	1,299	ebay.com
3.		Canon T2i	..	+ +	..	77/100	4/5	4.5/5	Feb 2010	699	ebay.com
4.		Nikon D3100	5/5	+ +	..	72/100	4.5/5	4.5/5	Aug 2010	599	ebay.com
5.		Nikon D3200	5/5	+ +	..	73/100	4.5/5	4.5/5	Apr 2012	599	ebay.com
6.		Nikon D5000	..	+ +	..	75/100	4/5	4.5/5	Apr 2009	749	ebay.com
7.		Nikon D5200	4/5	+ +	..	79/100	4.5/5	4.5/5	Nov 2012	749	ebay.com
8.		Nikon D5300	4/5	+ +	..	79/100	4.5/5	4.5/5	Oct 2013	799	ebay.com
9.		Nikon D5500	5/5	+	..	79/100	4.5/5	4.5/5	Jan 2015	899	ebay.com
10.		Nikon D5600	4/5	..	4/5	79/100	4.5/5	4/5	Nov 2016	699	ebay.com
11.		Nikon D7000	4/5	..	..	80/100	4.5/5	4.5/5	Sep 2010	1,499	ebay.com
12.		Olympus E-M1	5/5	+ +	..	84/100	4.5/5	4.5/5	Sep 2013	1,399	ebay.com
13.		Olympus E-M5 II	5/5	+ +	4.5/5	81/100	5/5	5/5	Feb 2015	1,099	ebay.com
14.		Olympus E-P5	5/5	+ +	..	78/100	4.5/5	5/5	May 2013	999	ebay.com
15.		Olympus PEN-F	..	..	4/5	82/100	4.5/5	5/5	Jan 2016	1,199	ebay.com
16.		Panasonic GX7	4/5	+	..	79/100	5/5	5/5	Aug 2013	999	ebay.com
17.		Sony NEX-5N	3/5	+ +	..	79/100	4.5/5	4.5/5	Aug 2011	699	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

Care should be taken when interpreting the review scores above, though. The ratings were established in reference to similarly priced cameras that were available in the market at the time of the review. 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.

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Other camera comparisons

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