Olympus E-M5 vs Sony A5100

The Olympus OM-D E-M5 and the Sony Alpha A5100 are two digital cameras that were revealed to the public, respectively, in February 2012 and August 2014. Both the E-M5 and the A5100 are mirrorless interchangeable lens cameras that are based on a Four Thirds (E-M5) and an APS-C (A5100) sensor. The Olympus has a resolution of 15.9 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.

Headline Specifications

Olympus E-M5		Sony A5100
Mirrorless system camera		Mirrorless system camera
Micro Four Thirds lenses		Sony E mount lenses
15.9 MP – Four Thirds sensor		24 MP – APS-C sensor
1080/60i Video		1080/60p Video
ISO 200-25,600		ISO 100-25,600
Electronic viewfinder (1440k dots)		No viewfinder, LCD framing
3.0" LCD – 610k dots		3.0" LCD – 922k dots
Tilting touchscreen		Tilting touchscreen
9 shutter flaps per second		6 shutter flaps per second
In-body stabilization		Lens stabilization only
Weathersealed body		not weather sealed
360 shots per battery charge		400 shots per battery charge
122 x 89 x 43 mm, 425 g		110 x 63 x 36 mm, 283 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Olympus OM-D E-M5 and the Sony Alpha A5100? 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 physical size and weight of the Olympus E-M5 and the Sony A5100 are illustrated 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 size dimensions are rounded to the nearest millimeter.

The E-M5 can be obtained in two different colors (black, silver), while the A5100 is also available in two color-versions, but different ones (black, white).

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Sony A5100 is considerably smaller (36 percent) than the Olympus E-M5. Moreover, the A5100 is markedly lighter (33 percent) than the E-M5. It is worth mentioning in this context that the E-M5 is splash and dust resistant, while the A5100 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 Micro Four Thirds Lens Catalog (E-M5) and the Sony E-Mount Lens Catalog (A5100). 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-M5 gets 360 shots out of its Olympus BLN-1 battery, while the A5100 can take 400 images on a single charge of its Sony NP-FW50 power pack. The power pack in the A5100 can be charged via the USB port, which can be very convenient when travelling.

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, 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.		Olympus E-M5	122 mm	89 mm	43 mm	425 g	360	Y	Feb 2012	1,299	ebay.com
2.		Sony A5100	110 mm	63 mm	36 mm	283 g	400	n	Aug 2014	549	ebay.com
3.		Olympus E-M1	130 mm	94 mm	63 mm	497 g	350	Y	Sep 2013	1,399	ebay.com
4.		Olympus E-M5 II	124 mm	85 mm	45 mm	469 g	310	Y	Feb 2015	1,099	ebay.com
5.		Olympus E-P5	122 mm	69 mm	37 mm	420 g	330	n	May 2013	999	ebay.com
6.		Olympus E-PL5	111 mm	64 mm	38 mm	325 g	360	n	Sep 2012	599	ebay.com
7.		Olympus E-PL7	115 mm	67 mm	38 mm	357 g	350	n	Aug 2014	599	ebay.com
8.		Olympus E-PM2	110 mm	64 mm	34 mm	269 g	360	n	Sep 2012	499	ebay.com
9.		Olympus PEN-F	125 mm	72 mm	37 mm	427 g	330	n	Jan 2016	1,199	ebay.com
10.		Panasonic GH3	133 mm	93 mm	82 mm	550 g	540	Y	Sep 2012	1,299	ebay.com
11.		Panasonic GX7	123 mm	71 mm	55 mm	402 g	350	n	Aug 2013	999	ebay.com
12.		Panasonic GX8	133 mm	78 mm	63 mm	487 g	330	Y	Jul 2015	1,199	ebay.com
13.		Sony A3000	128 mm	91 mm	85 mm	411 g	470	n	Aug 2013	329	ebay.com
14.		Sony A5000	110 mm	63 mm	36 mm	269 g	420	n	Jan 2014	449	ebay.com
15.		Sony A6000	120 mm	67 mm	45 mm	344 g	360	n	Feb 2014	599	ebay.com
16.		Sony NEX-3	117 mm	62 mm	33 mm	297 g	330	n	May 2010	599	ebay.com
17.		Sony NEX-3N	110 mm	62 mm	35 mm	269 g	480	n	Feb 2013	499	ebay.com
Note: Measurements and pricing do not include easily detachable parts, such as add-on or interchangeable lenses or optional viewfinders.
Convert to Imperial

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 A5100 was launched at a markedly lower price (by 58 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. 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 generally have larger individual pixels that offer better low-light sensitivity, provide wider dynamic range, and have 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 tend to be more expensive and lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Olympus E-M5 features a Four Thirds sensor and the Sony A5100 an APS-C sensor. The sensor area in the A5100 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-M5 has a native 4:3 aspect ratio, while the one in the A5100 offers a 3:2 aspect.

With 24MP, the A5100 offers a higher resolution than the E-M5 (15.9MP), but the A5100 nevertheless has larger individual pixels (pixel pitch of 3.91μm versus 3.76μm for the E-M5) due to its larger sensor. Moreover, the A5100 is a much more recent model (by 2 years and 6 months) than the E-M5, and its sensor will have benefitted from technological advances during this time that further enhance the light gathering capacity of its pixel-units.

The resolution advantage of the Sony A5100 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A5100 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-M5 are 23 x 17.3 inches or 58.5 x 43.9 cm for good quality, 18.4 x 13.8 inches or 46.8 x 35.1 cm for very good quality, and 15.4 x 11.5 inches or 39 x 29.3 cm for excellent quality prints.

The A5100 has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

The Olympus OM-D E-M5 has a native sensitivity range from ISO 200 to ISO 25600. The corresponding ISO settings for the Sony Alpha A5100 are ISO 100 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.

Since 2007, DXO Mark has published sensor performance measurements that have been derived using a consistent methodology. 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 A5100 has a markedly higher DXO score than the E-M5 (overall score 9 points higher), which will translate into better image quality. The advantage is based on 1 bits higher color depth, 0.4 EV in additional dynamic range, and 0.7 stops in additional low light sensitivity. The following table provides an overview of the physical sensor characteristics, as well as the sensor quality measurements for a selection of comparators.

Sensor Characteristics

		Camera Model	Sensor Class	Resolution (MP)	Horiz. Pixels	Vert. Pixels	Video Format	DXO Portrait	DXO Landscape	DXO Sports	DXO Overall
1.		Olympus E-M5	Four Thirds	15.9	4608	3456	1080/60i	22.8	12.3	826	71
2.		Sony A5100	APS-C	24.0	6000	4000	1080/60p	23.8	12.7	1347	80
3.		Olympus E-M1	Four Thirds	15.9	4608	3456	1080/30p	23.0	12.7	757	73
4.		Olympus E-M5 II	Four Thirds	15.9	4608	3456	1080/60p	23.0	12.5	842	73
5.		Olympus E-P5	Four Thirds	15.9	4608	3456	1080/30p	22.8	12.4	895	72
6.		Olympus E-PL5	Four Thirds	15.9	4608	3456	1080/30p	22.8	12.3	889	72
7.		Olympus E-PL7	Four Thirds	15.9	4608	3456	1080/30p	22.7	12.4	873	72
8.		Olympus E-PM2	Four Thirds	15.9	4608	3456	1080/30p	22.7	12.2	932	72
9.		Olympus PEN-F	Four Thirds	20.2	5184	3888	1080/60p	23.1	12.4	894	74
10.		Panasonic GH3	Four Thirds	15.9	4608	3456	1080/60p	22.7	12.4	812	71
11.		Panasonic GX7	Four Thirds	15.8	4592	3448	1080/60p	22.6	12.2	718	70
12.		Panasonic GX8	Four Thirds	20.2	5184	3888	4K/30p	23.5	12.6	806	75
13.		Sony A3000	APS-C	19.8	5456	3632	1080/60i	23.7	12.8	1068	78
14.		Sony A5000	APS-C	19.8	5456	3632	1080/60i	23.8	13.0	1089	79
15.		Sony A6000	APS-C	24.0	6000	4000	1080/60p	24.1	13.1	1347	82
16.		Sony NEX-3	APS-C	14.0	4592	3056	720/30p	22.1	12.0	830	68
17.		Sony NEX-3N	APS-C	16.0	4912	3264	1080/60i	22.8	12.5	1067	74

Many modern cameras cannot only take still pictures, but also record videos. Both cameras under consideration are equipped with sensors that have a sufficiently high read-out speed for moving images, but the A5100 provides a faster frame rate than the E-M5. It can shoot movie footage at 1080/60p, while the Olympus is limited to 1080/60i.

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. For example, the E-M5 has an electronic viewfinder (1440k dots), which can be very helpful when shooting in bright sunlight. In contrast, the A5100 relies on live view and the rear LCD for framing. The adjacent table lists some of the other core features of the Olympus E-M5 and Sony A5100 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.		Olympus E-M5	1440	n	3.0 / 610	tilting	Y	1/4000s	9.0/s	n	Y
2.		Sony A5100	none	n	3.0 / 922	tilting	Y	1/4000s	6.0/s	Y	n
3.		Olympus E-M1	2360	n	3.0 / 1037	tilting	Y	1/8000s	10.0/s	n	Y
4.		Olympus E-M5 II	2360	n	3.0 / 1037	swivel	Y	1/8000s	10.0/s	n	Y
5.		Olympus E-P5	optional	n	3.0 / 1037	tilting	Y	1/8000s	9.0/s	Y	Y
6.		Olympus E-PL5	optional	n	3.0 / 460	tilting	Y	1/4000s	8.0/s	n	Y
7.		Olympus E-PL7	optional	n	3.0 / 1037	tilting	Y	1/4000s	8.0/s	n	Y
8.		Olympus E-PM2	optional	n	3.0 / 460	fixed	Y	1/4000s	8.0/s	n	Y
9.		Olympus PEN-F	2360	n	3.0 / 1037	swivel	Y	1/8000s	10.0/s	n	Y
10.		Panasonic GH3	1746	n	3.0 / 614	swivel	Y	1/4000s	6.0/s	Y	n
11.		Panasonic GX7	2760	n	3.0 / 1040	tilting	Y	1/8000s	5.0/s	Y	Y
12.		Panasonic GX8	2360	n	3.0 / 1040	swivel	Y	1/8000s	10.0/s	n	Y
13.		Sony A3000	202	n	3.0 / 230	fixed	n	1/4000s	2.5/s	Y	n
14.		Sony A5000	none	n	3.0 / 461	tilting	n	1/4000s	3.5/s	Y	n
15.		Sony A6000	1440	n	3.0 / 922	tilting	n	1/4000s	11.0/s	Y	n
16.		Sony NEX-3	optional	n	3.0 / 920	tilting	n	1/4000s	7.0/s	n	n
17.		Sony NEX-3N	optional	n	3.0 / 460	tilting	n	1/4000s	4.0/s	Y	n
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that differentiates the E-M5 and the A5100 is in-body image stabilization (IBIS). The E-M5 reduces the risk of handshake-induced blur with all attached lenses, while the A5100 offers no blur reduction with lenses that themselves do not provide optical image stabilization.

The E-M5 writes its imaging data to SDXC cards, while the A5100 uses SDXC or Memory Stick PRO Duo 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 Olympus OM-D E-M5 and Sony Alpha A5100 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.		Olympus E-M5	Y	stereo / mono	-	-	mini	2.0	-	-	-
2.		Sony A5100	-	stereo / mono	-	-	micro	2.0	Y	Y	-
3.		Olympus E-M1	Y	stereo / mono	Y	-	micro	2.0	Y	-	-
4.		Olympus E-M5 II	Y	stereo / mono	Y	-	micro	2.0	Y	-	-
5.		Olympus E-P5	Y	stereo / mono	-	-	micro	2.0	Y	-	-
6.		Olympus E-PL5	Y	stereo / mono	-	-	mini	2.0	-	-	-
7.		Olympus E-PL7	Y	stereo / mono	-	-	micro	2.0	Y	-	-
8.		Olympus E-PM2	Y	stereo / mono	-	-	mini	2.0	-	-	-
9.		Olympus PEN-F	Y	stereo / mono	-	-	micro	2.0	Y	-	-
10.		Panasonic GH3	Y	stereo / mono	Y	Y	mini	2.0	Y	-	-
11.		Panasonic GX7	Y	stereo / mono	-	-	mini	2.0	Y	Y	-
12.		Panasonic GX8	Y	stereo / mono	Y	-	micro	2.0	Y	Y	-
13.		Sony A3000	Y	stereo / mono	-	-	mini	2.0	-	-	-
14.		Sony A5000	-	stereo / mono	-	-	micro	2.0	Y	Y	-
15.		Sony A6000	Y	stereo / mono	-	-	micro	2.0	Y	Y	-
16.		Sony NEX-3	Y	stereo / mono	-	-	mini	2.0	-	-	-
17.		Sony NEX-3N	-	stereo / mono	-	-	micro	2.0	-	-	-

It is notable that the E-M5 has a hotshoe, while the A5100 does not. This socket makes it possible to easily attach optional accessories, such as an external flash gun.

Both the E-M5 and the A5100 have been discontinued, but can regularly be found used on ebay. The E-M5 was replaced by the Olympus E-M5 II, while the A5100 does not have a direct successor. Further information on the features and operation of the E-M5 and A5100 can be found, respectively, in the Olympus E-M5 Manual (free pdf) or the online Sony A5100 Manual.

Review summary

So what conclusions can be drawn? Is there a clear favorite between the Olympus E-M5 and the Sony A5100? Which camera is better? The listing below highlights the relative strengths of the two models.

Arguments in favor of the Olympus OM-D E-M5:

• Easier framing: Has an electronic viewfinder for image composition and settings control.
• Faster burst: Shoots at higher frequency (9 vs 6 flaps/sec) to capture the decisive moment.
• Better sealing: Is weather sealed to enable shooting in dusty or wet environments.
• Sharper images: Has hand-shake reducing image stabilization built-in.
• Better lighting: Features a hotshoe and can thus hold and trigger an external flash gun.
• More heavily discounted: Has been available for much longer (launched in February 2012).

Advantages of the Sony Alpha A5100:

• More detail: Has more megapixels (24 vs 15.9MP), which boosts linear resolution by 25%.
• Better image quality: Scores markedly higher (9 points) in the DXO overall evaluation.
• Better low-light sensitivity: Can shoot in dim conditions (0.7 stops ISO advantage).
• Better video: Provides higher movie framerates (1080/60p versus 1080/60i).
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• More detailed LCD: Has a higher resolution rear screen (922k vs 610k dots).
• More selfie-friendly: Has an articulated screen that can be turned to be front-facing.
• More compact: Is smaller (110x63mm vs 122x89mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 142g or 33 percent) and is thus easier to take along.
• Longer lasting: Gets more shots (400 versus 360) out of a single battery charge.
• Easier travel charging: Can be conveniently charged via its USB port.
• Easier fill-in: Has a small integrated flash to brighten shadows of backlit subjects.
• Easier file upload: Has wifi built in for automatic backup or image transfer to the web.
• Easier device pairing: Supports NFC for fast wireless image transfer over short distances.
• More affordable: Was introduced into a lower priced category (58 percent cheaper at launch).
• More modern: Reflects 2 years and 6 months of technical progress since the E-M5 launch.

If the count of relative strengths (bullet points above) is taken as a measure, the A5100 is the clear winner of the contest (16 : 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-M5 and the Sony A5100 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 specs-based evaluation of cameras can be instructive in revealing their potential as photographic tools, it says little about, for example, the shooting experience and imaging performance of the E-M5 and the A5100 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 hands-on reviews by experts 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.		Olympus E-M5	4/5	+ +	..	80/100	4.5/5	5/5	Feb 2012	1,299	ebay.com
2.		Sony A5100	4.5/5	+	..	..	4.5/5	5/5	Aug 2014	549	ebay.com
3.		Olympus E-M1	5/5	+ +	..	84/100	4.5/5	4.5/5	Sep 2013	1,399	ebay.com
4.		Olympus E-M5 II	5/5	+ +	4.5/5	81/100	5/5	5/5	Feb 2015	1,099	ebay.com
5.		Olympus E-P5	5/5	+ +	..	78/100	4.5/5	5/5	May 2013	999	ebay.com
6.		Olympus E-PL5	3/5	+ +	..	..	4.5/5	4.5/5	Sep 2012	599	ebay.com
7.		Olympus E-PL7	4/5	+	..	..	5/5	4/5	Aug 2014	599	ebay.com
8.		Olympus E-PM2	3/5	..	..	77/100	5/5	4.5/5	Sep 2012	499	ebay.com
9.		Olympus PEN-F	..	..	4/5	82/100	4.5/5	5/5	Jan 2016	1,199	ebay.com
10.		Panasonic GH3	5/5	+ +	..	79/100	4.5/5	4.5/5	Sep 2012	1,299	ebay.com
11.		Panasonic GX7	4/5	+	..	79/100	5/5	5/5	Aug 2013	999	ebay.com
12.		Panasonic GX8	5/5	+	..	82/100	4.5/5	4.5/5	Jul 2015	1,199	ebay.com
13.		Sony A3000	3/5	+	..	..	4/5	4/5	Aug 2013	329	ebay.com
14.		Sony A5000	3/5	+	..	..	4.5/5	4.5/5	Jan 2014	449	ebay.com
15.		Sony A6000	5/5	+	4.5/5	80/100	4.5/5	5/5	Feb 2014	599	ebay.com
16.		Sony NEX-3	..	..	..	70/100	4.5/5	4/5	May 2010	599	ebay.com
17.		Sony NEX-3N	3/5	..	..	..	4.5/5	4.5/5	Feb 2013	499	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The review scores listed above should be treated with care, though. The ratings are only valid when referring to cameras in the same category and of the same age. Thus, a score needs to be put into the context of the launch date and the launch price of the camera, and comparing ratings of very distinct cameras or ones that are far apart in terms of their release date 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

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 use the search menu below. As an alternative, you can also directly jump to any one of the listed comparisons that were previously generated by the CAM-parator tool.

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