Olympus E-PM1 vs Sony A7

The Olympus PEN E-PM1 and the Sony Alpha A7 are two digital cameras that were revealed to the public, respectively, in June 2011 and October 2013. Both the E-PM1 and the A7 are mirrorless interchangeable lens cameras that are based on a Four Thirds (E-PM1) and a full frame (A7) sensor. The Olympus has a resolution of 12.2 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-PM1		Sony A7
Mirrorless system camera		Mirrorless system camera
Micro Four Thirds lenses		Sony E mount lenses
12.2 MP – Four Thirds sensor		24 MP – Full Frame sensor
1080/60i Video		1080/60p Video
ISO 100-12,800		ISO 100-25,600 (50 - 51,200)
Viewfinder optional		Electronic viewfinder (2400k dots)
3.0" LCD – 460k dots		3.0" LCD – 1230k dots
Fixed screen (not touch-sensitive)		Tilting screen (no touchscreen)
5.5 shutter flaps per second		5 shutter flaps per second
In-body stabilization		Lens stabilization only
not weather sealed		Weathersealed body
330 shots per battery charge		340 shots per battery charge
110 x 64 x 34 mm, 265 g		127 x 94 x 48 mm, 474 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Olympus PEN E-PM1 and the Sony Alpha A7? 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

An illustration of the physical size and weight of the Olympus E-PM1 and the Sony A7 is provided in the side-by-side display below. The two cameras are presented according to their relative size. Three consecutive perspectives from the front, the top, and the back are available. All width, height and depth measures are rounded to the nearest millimeter.

The E-PM1 can be obtained in six different colors (black, silver, brown, pink, purple, white), while the A7 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 Sony A7 is considerably larger (70 percent) than the Olympus E-PM1. Moreover, the A7 is substantially heavier (79 percent) than the E-PM1. It is noteworthy in this context that the A7 is splash and dust-proof, while the E-PM1 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-PM1) and the Sony FE Lens Catalog (A7). 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-PM1 gets 330 shots out of its Olympus BLS-5 battery, while the A7 can take 340 images on a single charge of its Sony NP-FW50 power pack. The power pack in the A7 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-PM1	110 mm	64 mm	34 mm	265 g	330	n	Jun 2011	499	ebay.com
2.		Sony A7	127 mm	94 mm	48 mm	474 g	340	Y	Oct 2013	1,699	ebay.com
3.		Olympus E-PL5	111 mm	64 mm	38 mm	325 g	360	n	Sep 2012	599	ebay.com
4.		Olympus E-PM2	110 mm	64 mm	34 mm	269 g	360	n	Sep 2012	499	ebay.com
5.		Olympus E-P3	122 mm	69 mm	34 mm	369 g	330	n	Jun 2011	799	ebay.com
6.		Olympus E-PL2	114 mm	72 mm	42 mm	362 g	280	n	Jan 2011	599	ebay.com
7.		Olympus E-PL3	110 mm	64 mm	37 mm	313 g	300	n	Jun 2011	599	ebay.com
8.		Olympus E-PL1	115 mm	72 mm	42 mm	334 g	290	n	Feb 2010	599	ebay.com
9.		Panasonic GF5	108 mm	67 mm	37 mm	267 g	360	n	Apr 2012	499	ebay.com
10.		Panasonic GF3	108 mm	67 mm	32 mm	264 g	300	n	Jun 2011	549	ebay.com
11.		Panasonic G2	124 mm	84 mm	74 mm	428 g	360	n	Mar 2010	599	ebay.com
12.		Panasonic GF2	113 mm	68 mm	33 mm	310 g	300	n	Nov 2010	549	ebay.com
13.		Sony A7 II	127 mm	96 mm	60 mm	599 g	350	Y	Nov 2014	1,999	ebay.com
14.		Sony A7S	127 mm	94 mm	48 mm	489 g	380	Y	Apr 2014	2,499	ebay.com
15.		Sony A7R	127 mm	94 mm	48 mm	465 g	340	Y	Oct 2013	2,299	ebay.com
16.		Sony RX1R	113 mm	65 mm	70 mm	482 g	270	n	Jun 2013	2,799	ebay.com
17.		Sony RX1	113 mm	65 mm	70 mm	482 g	270	n	Sep 2012	2,799	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

Any camera decision will naturally be influenced heavily by the price. 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 E-PM1 was launched at a markedly lower price (by 71 percent) than the A7, which puts it into a different market segment. 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 size of the sensor inside a digital camera is one of the key determinants 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 associated with larger, more expensive camera bodies and lenses.

Of the two cameras under consideration, the Olympus E-PM1 features a Four Thirds sensor and the Sony A7 a full frame sensor. The sensor area in the A7 is 280 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 2.0 and 1.0. The sensor in the E-PM1 has a native 4:3 aspect ratio, while the one in the A7 offers a 3:2 aspect.

With 24MP, the A7 offers a higher resolution than the E-PM1 (12.2MP), but the A7 nevertheless has larger individual pixels (pixel pitch of 5.97μm versus 4.29μm for the E-PM1) due to its larger sensor. Moreover, the A7 is a much more recent model (by 2 years and 3 months) than the E-PM1, 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 A7 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A7 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-PM1 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 A7 has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

The Olympus PEN E-PM1 has a native sensitivity range from ISO 100 to ISO 12800. The corresponding ISO settings for the Sony Alpha A7 are ISO 100 to ISO 25600, with the possibility to increase the ISO range to 50-51200.

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.

For many cameras, data on sensor performance has been reported by DXO Mark. This service is based on lab testing and assigns an overall score to each camera sensor, as well as ratings for dynamic range ("DXO Landscape"), color depth ("DXO Portrait"), and low-light sensitivity ("DXO Sports"). Of the two cameras under consideration, the A7 offers substantially better image quality than the E-PM1 (overall score 38 points higher). The advantage is based on 3.8 bits higher color depth, 3.9 EV in additional dynamic range, and 2.2 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-PM1	Four Thirds	12.2	4032	3024	1080/60i	21.0	10.3	499	52
2.		Sony A7	Full Frame	24.0	6000	4000	1080/60p	24.8	14.2	2248	90
3.		Olympus E-PL5	Four Thirds	15.9	4608	3456	1080/30p	22.8	12.3	889	72
4.		Olympus E-PM2	Four Thirds	15.9	4608	3456	1080/30p	22.7	12.2	932	72
5.		Olympus E-P3	Four Thirds	12.2	4032	3024	1080/60i	20.8	10.1	536	51
6.		Olympus E-PL2	Four Thirds	12.2	4032	3024	720/30p	21.4	10.2	573	55
7.		Olympus E-PL3	Four Thirds	12.2	4032	3024	1080/60i	20.9	10.3	499	52
8.		Olympus E-PL1	Four Thirds	12.2	4032	3024	720/30p	21.5	10.1	487	54
9.		Panasonic GF5	Four Thirds	12.0	4000	3000	1080/60i	20.5	10.0	573	50
10.		Panasonic GF3	Four Thirds	12.0	4000	3000	1080/60i	20.6	10.1	459	50
11.		Panasonic G2	Four Thirds	12.0	4000	3000	720/30p	21.2	10.3	493	53
12.		Panasonic GF2	Four Thirds	12.0	4000	3000	1080/60i	21.2	10.3	506	54
13.		Sony A7 II	Full Frame	24.0	6000	4000	1080/60p	24.9	13.6	2449	90
14.		Sony A7S	Full Frame	12.0	4240	2832	1080/60p	23.9	13.2	3702	87
15.		Sony A7R	Full Frame	36.2	7360	4912	1080/60p	25.6	14.1	2746	95
16.		Sony RX1R	Full Frame	24.0	6000	4000	1080/60p	25.0	13.6	2537	91
17.		Sony RX1	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 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 A7 provides a faster frame rate than the E-PM1. 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 A7 has an electronic viewfinder (2400k dots), which can be very helpful when shooting in bright sunlight. In contrast, the E-PM1 relies on live view and the rear LCD for framing. That said, the E-PM1 can be equipped with an optional viewfinder – the VF-2. The table below summarizes some of the other core capabilities of the Olympus E-PM1 and Sony A7 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.		Olympus E-PM1	optional	n	3.0 / 460	fixed	n	1/4000s	5.5/s	n	Y
2.		Sony A7	2400	n	3.0 / 1230	tilting	n	1/8000s	5.0/s	n	n
3.		Olympus E-PL5	optional	n	3.0 / 460	tilting	Y	1/4000s	8.0/s	n	Y
4.		Olympus E-PM2	optional	n	3.0 / 460	fixed	Y	1/4000s	8.0/s	n	Y
5.		Olympus E-P3	optional	n	3.0 / 614	fixed	Y	1/4000s	3.0/s	Y	Y
6.		Olympus E-PL2	optional	n	3.0 / 460	fixed	n	1/4000s	3.0/s	Y	Y
7.		Olympus E-PL3	optional	n	3.0 / 460	tilting	n	1/4000s	5.5/s	n	Y
8.		Olympus E-PL1	optional	n	2.7 / 230	fixed	n	1/2000s	3.0/s	Y	Y
9.		Panasonic GF5	none	n	3.0 / 920	fixed	Y	1/4000s	4.0/s	Y	n
10.		Panasonic GF3	none	n	3.0 / 460	fixed	Y	1/4000s	3.2/s	Y	n
11.		Panasonic G2	1440	n	3.0 / 460	swivel	Y	1/4000s	2.6/s	Y	n
12.		Panasonic GF2	optional	n	3.0 / 460	fixed	Y	1/4000s	2.6/s	Y	n
13.		Sony A7 II	2400	n	3.0 / 1230	tilting	n	1/8000s	5.0/s	n	Y
14.		Sony A7S	2400	n	3.0 / 921	tilting	n	1/8000s	5.0/s	n	n
15.		Sony A7R	2400	n	3.0 / 1230	tilting	n	1/8000s	4.0/s	n	n
16.		Sony RX1R	optional	n	3.0 / 1229	fixed	n	1/4000s	5.0/s	Y	n
17.		Sony RX1	optional	n	3.0 / 1229	fixed	n	1/4000s	5.0/s	Y	n
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that differentiates the E-PM1 and the A7 is in-body image stabilization (IBIS). The E-PM1 reduces the risk of handshake-induced blur with all attached lenses, while the A7 offers no blur reduction with lenses that themselves do not provide optical image stabilization.

The E-PM1 writes its imaging data to SDXC cards, while the A7 uses SDXC or Memory Stick PRO Duo cards. The A7 supports UHS-I cards (Ultra High Speed data transfer of up to 104 MB/s), while the E-PM1 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 Olympus PEN E-PM1 and Sony Alpha A7 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-PM1	Y	stereo / mono	-	-	mini	2.0	-	-	-
2.		Sony A7	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
3.		Olympus E-PL5	Y	stereo / mono	-	-	mini	2.0	-	-	-
4.		Olympus E-PM2	Y	stereo / mono	-	-	mini	2.0	-	-	-
5.		Olympus E-P3	Y	stereo / -	-	-	mini	2.0	-	-	-
6.		Olympus E-PL2	Y	stereo / -	-	-	mini	2.0	-	-	-
7.		Olympus E-PL3	Y	stereo / -	-	-	mini	2.0	-	-	-
8.		Olympus E-PL1	Y	stereo / -	-	-	mini	2.0	-	-	-
9.		Panasonic GF5	-	stereo / mono	-	-	mini	2.0	-	-	-
10.		Panasonic GF3	-	stereo / mono	-	-	mini	2.0	-	-	-
11.		Panasonic G2	Y	stereo / mono	-	-	mini	2.0	-	-	-
12.		Panasonic GF2	Y	stereo / mono	-	-	mini	2.0	-	-	-
13.		Sony A7 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
14.		Sony A7S	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
15.		Sony A7R	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
16.		Sony RX1R	Y	stereo / mono	Y	-	mini	2.0	-	-	-
17.		Sony RX1	Y	stereo / mono	Y	-	mini	2.0	-	-	-

It is notable that the A7 offers wifi support, which can be a very convenient means to transfer image data to an off-camera location. In contrast, the E-PM1 does not provide wifi capability.

Both the E-PM1 and the A7 have been discontinued, but can regularly be found used on ebay. The E-PM1 was replaced by the Olympus E-PM2, while the A7 was followed by the Sony A7 II. Further information on the features and operation of the E-PM1 and A7 can be found, respectively, in the Olympus E-PM1 Manual (free pdf) or the online Sony A7 Manual.

Review summary

So what is the bottom line? Is there a clear favorite between the Olympus E-PM1 and the Sony A7? Which camera is better? The listing below highlights the relative strengths of the two models.

Reasons to prefer the Olympus PEN E-PM1:

• More compact: Is smaller (110x64mm vs 127x94mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 209g or 44 percent) and hence easier to carry around.
• Sharper images: Has hand-shake reducing image stabilization built-in.
• More affordable: Was introduced into a lower priced category (71 percent cheaper at launch).
• More heavily discounted: Has been available for much longer (launched in June 2011).

Advantages of the Sony Alpha A7:

• More detail: Has more megapixels (24 vs 12.2MP), which boosts linear resolution by 43%.
• Better image quality: Scores substantially higher (38 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (3.8 bits more color depth).
• More dynamic range: Captures a broader range of light and dark details (3.9 EV of extra DR).
• Better low-light sensitivity: Can shoot in dim conditions (2.2 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.
• Better sound: Can connect to an external microphone for higher quality sound recording.
• Better sound control: Has a headphone port that enables audio monitoring while recording.
• Easier framing: Has an electronic viewfinder for image composition and settings control.
• More detailed LCD: Has a higher resolution rear screen (1230k vs 460k dots).
• More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
• Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
• Easier travel charging: Can be conveniently charged via its USB port.
• Better sealing: Is splash and dust sealed for shooting in inclement weather conditions.
• 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.
• Faster buffer clearing: Has an SD card interface that supports the UHS-I standard.
• More modern: Reflects 2 years and 3 months of technical progress since the E-PM1 launch.

If the number of relative strengths (bullet points above) is taken as a guide, the A7 is the clear winner of the contest (19 : 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 Olympus E-PM1 and the Sony A7 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 comparison of technical specifications can provide a useful overview of the capabilities of different cameras, it says little about, for example, the shooting experience and imaging performance of the E-PM1 and the A7 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.

Expert reviews

This is why hands-on reviews by experts are important. The table below provides a synthesis of the camera assessments of some of the best known photo-gear 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-PM1	..	86/100	..	71/100	4.5/5	4.5/5	Jun 2011	499	ebay.com
2.		Sony A7	5/5	+ +	..	80/100	5/5	5/5	Oct 2013	1,699	ebay.com
3.		Olympus E-PL5	3/5	+ +	..	..	4.5/5	4.5/5	Sep 2012	599	ebay.com
4.		Olympus E-PM2	3/5	..	..	77/100	5/5	4.5/5	Sep 2012	499	ebay.com
5.		Olympus E-P3	..	83/100	..	74/100	4.5/5	4.5/5	Jun 2011	799	ebay.com
6.		Olympus E-PL2	3/5	83/100	..	71/100	4.5/5	4.5/5	Jan 2011	599	ebay.com
7.		Olympus E-PL3	3/5	+ +	..	72/100	4.5/5	4/5	Jun 2011	599	ebay.com
8.		Olympus E-PL1	..	86/100	..	69/100	4/5	4.5/5	Feb 2010	599	ebay.com
9.		Panasonic GF5	3/5	..	..	..	4.5/5	4.5/5	Apr 2012	499	ebay.com
10.		Panasonic GF3	3/5	82/100	..	71/100	4.5/5	4/5	Jun 2011	549	ebay.com
11.		Panasonic G2	..	..	..	72/100	4/5	4.5/5	Mar 2010	599	ebay.com
12.		Panasonic GF2	3/5	82/100	..	70/100	4.5/5	4.5/5	Nov 2010	549	ebay.com
13.		Sony A7 II	5/5	+	4/5	82/100	4.5/5	5/5	Nov 2014	1,999	ebay.com
14.		Sony A7S	4/5	..	..	86/100	4.5/5	5/5	Apr 2014	2,499	ebay.com
15.		Sony A7R	5/5	+ +	..	82/100	4.5/5	5/5	Oct 2013	2,299	ebay.com
16.		Sony RX1R	5/5	..	..	..	4/5	4.5/5	Jun 2013	2,799	ebay.com
17.		Sony RX1	5/5	..	..	79/100	4/5	4.5/5	Sep 2012	2,799	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The above review scores should be interpreted 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. A score, therefore, has to be seen in close connection to the price and market introduction time of the camera, and rating-comparisons among cameras that span long time periods or concern very differently equipped models make little sense. 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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