Nikon D5100 vs Olympus E-P2

The Nikon D5100 and the Olympus PEN E-P2 are two digital cameras that were officially introduced, respectively, in April 2011 and November 2009. The D5100 is a DSLR, while the E-P2 is a mirrorless interchangeable lens camera. The cameras are based on an APS-C (D5100) and a Four Thirds (E-P2) sensor. The Nikon has a resolution of 16.1 megapixels, whereas the Olympus provides 12.2 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-P2
Digital single lens reflex		Mirrorless system camera
Nikon F mount lenses		Micro Four Thirds lenses
16.1 MP – APS-C sensor		12.2 MP – Four Thirds sensor
1080/30p Video		720/30p Video
ISO 100-6,400 (100 - 25,600)		ISO 100-6,400
Optical viewfinder		Viewfinder optional
3.0" LCD – 921k dots		3.0" LCD – 230k dots
Swivel screen (not touch-sensitive)		Fixed screen (not touch-sensitive)
4 shutter flaps per second		3 shutter flaps per second
Lens stabilization only		In-body stabilization
660 shots per battery charge		300 shots per battery charge
128 x 97 x 79 mm, 560 g		121 x 70 x 36 mm, 355 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 PEN E-P2? 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-P2. The two cameras are presented according to their relative size. Three consecutive perspectives from the front, the top, and the back are available. All size dimensions are rounded to the nearest millimeter.

The E-P2 can be obtained in three different colors (black, silver, white), 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-P2 is considerably smaller (32 percent) than the Nikon D5100. Moreover, the E-P2 is substantially lighter (37 percent) than the D5100. In this context, it is worth noting that neither the D5100 nor the E-P2 are weather-sealed.

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-P2). Mirrorless cameras, such as the E-P2, 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-P2 can take 300 images on a single charge of its Olympus BLS-1 power pack.

The following table provides a synthesis of the main physical specifications of the two cameras and other similar ones. 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.

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-P2	121 mm	70 mm	36 mm	355 g	300	n	Nov 2009	799	ebay.com
3.		Canon T2i	129 mm	98 mm	62 mm	530 g	440	n	Feb 2010	699	ebay.com
4.		Nikon D5600	124 mm	97 mm	70 mm	465 g	970	n	Nov 2016	699	ebay.com
5.		Nikon D5500	124 mm	97 mm	70 mm	470 g	820	n	Jan 2015	899	ebay.com
6.		Nikon D5300	125 mm	98 mm	76 mm	480 g	600	n	Oct 2013	799	ebay.com
7.		Nikon D3200	125 mm	96 mm	77 mm	505 g	540	n	Apr 2012	599	ebay.com
8.		Nikon D5200	129 mm	98 mm	78 mm	555 g	500	n	Nov 2012	749	ebay.com
9.		Nikon D7000	132 mm	105 mm	77 mm	780 g	1050	Y	Sep 2010	1,499	ebay.com
10.		Nikon D3100	124 mm	96 mm	75 mm	505 g	550	n	Aug 2010	599	ebay.com
11.		Nikon D5000	127 mm	104 mm	80 mm	590 g	510	n	Apr 2009	749	ebay.com
12.		Olympus E-P3	122 mm	69 mm	34 mm	369 g	330	n	Jun 2011	799	ebay.com
13.		Olympus E-PL2	114 mm	72 mm	42 mm	362 g	280	n	Jan 2011	599	ebay.com
14.		Olympus E-PL3	110 mm	64 mm	37 mm	313 g	300	n	Jun 2011	599	ebay.com
15.		Olympus E-P1	121 mm	70 mm	36 mm	355 g	300	n	Jun 2009	799	ebay.com
16.		Panasonic GH1	124 mm	90 mm	45 mm	385 g	300	n	Mar 2009	899	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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The price is, of course, an important factor in any camera decision. 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 D5100 was somewhat cheaper (by 6 percent) than the E-P2 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.

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. 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. 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 are more costly to manufacture and tend to 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-P2 a Four Thirds sensor. The sensor area in the E-P2 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-P2 offers a 4:3 aspect.

With 16.1MP, the D5100 offers a higher resolution than the E-P2 (12.2MP), but the D5100 nevertheless has larger individual pixels (pixel pitch of 4.80μm versus 4.29μm for the E-P2) due to its larger sensor. Moreover, the D5100 is a somewhat more recent model (by 1 year and 4 months) than the E-P2, and its sensor might have benefitted from technological advances during this time that further enhance the light gathering capacity of its pixels.

The resolution advantage of the Nikon D5100 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the D5100 for good quality output (200 dots per inch) amounts to 24.6 x 16.3 inches or 62.6 x 41.5 cm, for very good quality (250 dpi) 19.7 x 13.1 inches or 50.1 x 33.2 cm, and for excellent quality (300 dpi) 16.4 x 10.9 inches or 41.7 x 27.6 cm. The corresponding values for the Olympus E-P2 are 20.2 x 15.1 inches or 51.2 x 38.4 cm for good quality, 16.1 x 12.1 inches or 41 x 30.7 cm for very good quality, and 13.4 x 10.1 inches or 34.1 x 25.6 cm for excellent quality prints.

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 PEN E-P2 are ISO 100 to ISO 6400 (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 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 D5100 provides substantially higher image quality than the E-P2, with an overall score that is 24 points higher. This advantage is based on 2 bits higher color depth, 3.2 EV in additional dynamic range, and 1.2 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-P2	Four Thirds	12.2	4032	3024	720/30p	21.5	10.4	505	56
3.		Canon T2i	APS-C	17.9	5184	3456	1080/30p	22.1	11.5	784	66
4.		Nikon D5600	APS-C	24.0	6000	4000	1080/60p	24.1	14.0	1306	84
5.		Nikon D5500	APS-C	24.0	6000	4000	1080/60p	24.1	14.0	1438	84
6.		Nikon D5300	APS-C	24.0	6000	4000	1080/60p	24.0	13.9	1338	83
7.		Nikon D3200	APS-C	24.1	6016	4000	1080/30p	24.1	13.2	1131	81
8.		Nikon D5200	APS-C	24.0	6000	4000	1080/60i	24.2	13.9	1284	84
9.		Nikon D7000	APS-C	16.1	4928	3264	1080/24p	23.5	13.9	1167	80
10.		Nikon D3100	APS-C	14.2	4608	3072	1080/24p	22.5	11.3	919	67
11.		Nikon D5000	APS-C	12.2	4288	2848	720/24p	22.7	12.5	868	72
12.		Olympus E-P3	Four Thirds	12.2	4032	3024	1080/60i	20.8	10.1	536	51
13.		Olympus E-PL2	Four Thirds	12.2	4032	3024	720/30p	21.4	10.2	573	55
14.		Olympus E-PL3	Four Thirds	12.2	4032	3024	1080/60i	20.9	10.3	499	52
15.		Olympus E-P1	Four Thirds	12.2	4032	3024	720/30p	21.4	10.4	536	55
16.		Panasonic GH1	Four Thirds	12.0	4000	3000	1080/24p	21.6	11.6	772	64
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 also of capturing video footage. The two cameras under consideration both have sensors whose read-out speed is fast enough to capture moving pictures, but the D5100 provides a higher video resolution than the E-P2. It can shoot video footage at 1080/30p, while the Olympus is limited to 720/30p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a range of features. For example, the D5100 has an optical viewfinder, which can be very useful when shooting in bright sunlight. In contrast, the E-P2 relies on live view and the rear LCD for framing. That said, the E-P2 can be equipped with an optional viewfinder – the VF-2. The adjacent table lists some of the other core features of the Nikon D5100 and Olympus E-P2 along with similar information for a selection of comparators.

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-P2	optional	n	3.0 / 230	fixed	n	1/4000s	3.0/s	n	Y
3.		Canon T2i	optical	n	3.0 / 1040	fixed	n	1/4000s	3.7/s	Y	n
4.		Nikon D5600	optical	n	3.2 / 1037	swivel	Y	1/4000s	5.0/s	Y	n
5.		Nikon D5500	optical	n	3.2 / 1037	swivel	Y	1/4000s	5.0/s	Y	n
6.		Nikon D5300	optical	n	3.2 / 1037	swivel	n	1/4000s	5.0/s	Y	n
7.		Nikon D3200	optical	n	3.0 / 921	fixed	n	1/4000s	4.0/s	Y	n
8.		Nikon D5200	optical	n	3.0 / 921	swivel	n	1/4000s	5.0/s	Y	n
9.		Nikon D7000	optical	Y	3.0 / 921	fixed	n	1/8000s	6.0/s	Y	n
10.		Nikon D3100	optical	n	3.0 / 230	fixed	n	1/4000s	3.0/s	Y	n
11.		Nikon D5000	optical	n	2.7 / 230	full-flex	n	1/4000s	4.0/s	Y	n
12.		Olympus E-P3	optional	n	3.0 / 614	fixed	Y	1/4000s	3.0/s	Y	Y
13.		Olympus E-PL2	optional	n	3.0 / 460	fixed	n	1/4000s	3.0/s	Y	Y
14.		Olympus E-PL3	optional	n	3.0 / 460	tilting	n	1/4000s	5.5/s	n	Y
15.		Olympus E-P1	none	n	3.0 / 230	fixed	n	1/4000s	3.0/s	n	Y
16.		Panasonic GH1	1440	n	3.0 / 460	swivel	n	1/4000s	3.0/s	Y	n
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-P2 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.

The D5100 writes its imaging data to SDXC cards, while the E-P2 uses SDHC cards. The D5100 supports UHS-I cards (Ultra High Speed data transfer of up to 104 MB/s), while the E-P2 cannot take advantage of Ultra High Speed SD cards.

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 PEN E-P2 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-P2	Y	stereo / -	-	-	mini	2.0	-	-	-
3.		Canon T2i	Y	stereo / -	Y	-	mini	2.0	-	-	-
4.		Nikon D5600	Y	stereo / mono	Y	-	mini	2.0	Y	Y	Y
5.		Nikon D5500	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
6.		Nikon D5300	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
7.		Nikon D3200	Y	mono / mono	Y	-	mini	2.0	-	-	-
8.		Nikon D5200	Y	stereo / mono	Y	-	mini	2.0	-	-	-
9.		Nikon D7000	Y	mono / mono	Y	-	mini	2.0	-	-	-
10.		Nikon D3100	Y	mono / mono	-	-	mini	2.0	-	-	-
11.		Nikon D5000	Y	mono / mono	-	-	mini	2.0	-	-	-
12.		Olympus E-P3	Y	stereo / -	-	-	mini	2.0	-	-	-
13.		Olympus E-PL2	Y	stereo / -	-	-	mini	2.0	-	-	-
14.		Olympus E-PL3	Y	stereo / -	-	-	mini	2.0	-	-	-
15.		Olympus E-P1	Y	stereo / -	-	-	mini	2.0	-	-	-
16.		Panasonic GH1	Y	stereo / -	Y	-	mini	2.0	-	-	-
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-P2. 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-P2 have been discontinued, but can regularly be found used on ebay. The E-P2 was replaced by the Olympus E-P3, while the D5100 was followed by the Nikon D5200. Further information on the features and operation of the D5100 and E-P2 can be found, respectively, in the Nikon D5100 Manual (free pdf) or the online Olympus E-P2 Manual.

Review summary

So what conclusions can be drawn? Is there a clear favorite between the Nikon D5100 and the Olympus E-P2? Which camera is better? A synthesis of the relative strong points of each of the models is listed below.

Advantages of the Nikon D5100:

• More detail: Offers more megapixels (16.1 vs 12.2MP) with a 17% higher linear resolution.
• Better image quality: Scores substantially higher (24 points) in the DXO overall assessment.
• Richer colors: Generates images with noticeably better colors (2 bits more color depth).
• More dynamic range: Captures a larger spectrum of light and dark details (3.2 EV of extra DR).
• Better low-light sensitivity: Requires less light for good images (1.2 stops ISO advantage).
• Better video: Provides higher definition movie capture (1080/30p vs 720/30p).
• Better sound: Can connect to an external microphone for higher quality sound recording.
• Easier framing: Has an optical viewfinder for image composition and settings control.
• More detailed LCD: Has a higher resolution rear screen (921k vs 230k 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 (4 vs 3 flaps/sec) to capture the decisive moment.
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• Longer lasting: Can take more shots (660 versus 300) on a single battery charge.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• Faster buffer clearing: Has an SD card interface that supports the UHS-I standard.
• More modern: Is somewhat more recent (announced 1 year and 4 months after the E-P2).

Arguments in favor of the Olympus PEN E-P2:

• More compact: Is smaller (121x70mm vs 128x97mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 205g or 37 percent) and is thus easier to take along.
• 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 heavily discounted: Has been on the market for longer (launched in November 2009).

If the count of individual advantages (bullet points above) is taken as a guide, the D5100 is the clear winner of the match-up (17 : 5 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-P2 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 specs-based evaluation of cameras can be instructive in revealing their potential as photographic tools, it remains incomplete and does no justice, for example, to the way the D5100 or the E-P2 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.

Expert reviews

This is where reviews by experts come in. The following table reports the overall ratings of the cameras as published by some of the major 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-P2	3/5	+	..	69/100	4/5	4.5/5	Nov 2009	799	ebay.com
3.		Canon T2i	..	+ +	..	77/100	4/5	4.5/5	Feb 2010	699	ebay.com
4.		Nikon D5600	4/5	..	4/5	79/100	4.5/5	4/5	Nov 2016	699	ebay.com
5.		Nikon D5500	5/5	+	..	79/100	4.5/5	4.5/5	Jan 2015	899	ebay.com
6.		Nikon D5300	4/5	+ +	..	79/100	4.5/5	4.5/5	Oct 2013	799	ebay.com
7.		Nikon D3200	5/5	+ +	..	73/100	4.5/5	4.5/5	Apr 2012	599	ebay.com
8.		Nikon D5200	4/5	+ +	..	79/100	4.5/5	4.5/5	Nov 2012	749	ebay.com
9.		Nikon D7000	4/5	..	..	80/100	4.5/5	4.5/5	Sep 2010	1,499	ebay.com
10.		Nikon D3100	5/5	+ +	..	72/100	4.5/5	4.5/5	Aug 2010	599	ebay.com
11.		Nikon D5000	..	+ +	..	75/100	4/5	4.5/5	Apr 2009	749	ebay.com
12.		Olympus E-P3	..	83/100	..	74/100	4.5/5	4.5/5	Jun 2011	799	ebay.com
13.		Olympus E-PL2	3/5	83/100	..	71/100	4.5/5	4.5/5	Jan 2011	599	ebay.com
14.		Olympus E-PL3	3/5	+ +	..	72/100	4.5/5	4/5	Jun 2011	599	ebay.com
15.		Olympus E-P1	..	+	..	66/100	4/5	4.5/5	Jun 2009	799	ebay.com
16.		Panasonic GH1	..	+ +	..	72/100	4.5/5	4.5/5	Mar 2009	899	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.

The review scores listed above should be treated with care, though. The ratings were established in reference to similarly priced cameras that were available in the market at the time of the review. Hence, a score should always be seen in the context of the camera's market launch date and its price, and rating-comparisons among cameras that span long time periods or concern very differently equipped models make little sense. Also, kindly note that some of the listed sites have over time developped their review approaches and their reporting style.

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Other camera comparisons

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