Olympus E-PM1 vs Sony A7S II

The Olympus PEN E-PM1 and the Sony Alpha 7S II are two digital cameras that were announced, respectively, in June 2011 and September 2015. Both the E-PM1 and the A7S II are mirrorless interchangeable lens cameras that are based on a Four Thirds (E-PM1) and a full frame (A7S II) sensor. The Olympus has a resolution of 12.2 megapixels, whereas the Sony provides 12 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 A7S II
Mirrorless system camera		Mirrorless system camera
Micro Four Thirds lenses		Sony E mount lenses
12.2 MP – Four Thirds sensor		12 MP – Full Frame sensor
1080/60i Video		4K/30p Video
ISO 100-12,800		ISO 100-102,400 (50 - 409,600)
Viewfinder optional		Electronic viewfinder (2400k dots)
3.0" LCD – 460k dots		3.0" LCD – 1229k dots
Fixed screen (not touch-sensitive)		Tilting screen (no touchscreen)
5.5 shutter flaps per second		5 shutter flaps per second
In-body stabilization		In-body stabilization
not weather sealed		Weathersealed body
330 shots per battery charge		370 shots per battery charge
110 x 64 x 34 mm, 265 g		127 x 96 x 60 mm, 627 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 7S II? 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 Olympus E-PM1 and the Sony A7S II. 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-PM1 can be obtained in six different colors (black, silver, brown, pink, purple, white), while the A7S II 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 A7S II is considerably larger (73 percent) than the Olympus E-PM1. Moreover, the A7S II is substantially heavier (137 percent) than the E-PM1. It is noteworthy in this context that the A7S II 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 (A7S II). 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 A7S II can take 370 images on a single charge of its Sony NP-FW50 power pack. The power pack in the A7S II 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. In case you want to display and compare another camera duo, you can use the CAM-parator app to select your camera combination among a large number of options.

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 A7S II	127 mm	96 mm	60 mm	627 g	370	Y	Sep 2015	2,999	ebay.com
3.		Olympus E-P3	122 mm	69 mm	34 mm	369 g	330	n	Jun 2011	799	ebay.com
4.		Olympus E-PL1	115 mm	72 mm	42 mm	334 g	290	n	Feb 2010	599	ebay.com
5.		Olympus E-PL2	114 mm	72 mm	42 mm	362 g	280	n	Jan 2011	599	ebay.com
6.		Olympus E-PL3	110 mm	64 mm	37 mm	313 g	300	n	Jun 2011	599	ebay.com
7.		Olympus E-PL5	111 mm	64 mm	38 mm	325 g	360	n	Sep 2012	599	ebay.com
8.		Olympus E-PM2	110 mm	64 mm	34 mm	269 g	360	n	Sep 2012	499	ebay.com
9.		Panasonic G2	124 mm	84 mm	74 mm	428 g	360	n	Mar 2010	599	ebay.com
10.		Panasonic GF2	113 mm	68 mm	33 mm	310 g	300	n	Nov 2010	549	ebay.com
11.		Panasonic GF3	108 mm	67 mm	32 mm	264 g	300	n	Jun 2011	549	ebay.com
12.		Panasonic GF5	108 mm	67 mm	37 mm	267 g	360	n	Apr 2012	499	ebay.com
13.		Sony A7 IV	131 mm	96 mm	80 mm	659 g	580	Y	Oct 2021	2,499	amazon.com
14.		Sony A7R II	127 mm	96 mm	60 mm	625 g	290	Y	Jun 2015	3,199	ebay.com
15.		Sony A7R IV	129 mm	96 mm	78 mm	665 g	670	Y	Jul 2019	3,499	ebay.com
16.		Sony A7S	127 mm	94 mm	48 mm	489 g	380	Y	Apr 2014	2,499	ebay.com
17.		Sony A7S III	127 mm	97 mm	81 mm	699 g	600	Y	Jul 2020	3,499	amazon.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 manufacturer’s suggested retail prices give an idea on the placement of the camera in the maker’s lineup and the broader market. The E-PM1 was launched at a markedly lower price (by 83 percent) than the A7S II, 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 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 Olympus E-PM1 features a Four Thirds sensor and the Sony A7S II a full frame sensor. The sensor area in the A7S II is 276 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 A7S II offers a 3:2 aspect.

Despite having a smaller sensor, the Olympus E-PM1 offers a higher resolution of 12.2 megapixels, compared with 12 MP of the Sony A7S II. This megapixels advantage comes at the cost of a higher pixel density and a smaller size of the individual pixel (with a pixel pitch of 4.29μm versus 8.40μm for the A7S II). Moreover, it should be noted that the A7S II is much more recent (by 4 years and 2 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 Olympus PEN E-PM1 has a native sensitivity range from ISO 100 to ISO 12800. The corresponding ISO settings for the Sony Alpha 7S II are ISO 100 to ISO 102400, with the possibility to increase the ISO range to 50-409600.

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 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 A7S II offers substantially better image quality than the E-PM1 (overall score 33 points higher). The advantage is based on 2.6 bits higher color depth, 3 EV in additional dynamic range, and 2.6 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 A7S II	Full Frame	12.0	4240	2832	4K/30p	23.6	13.3	2993	85
3.		Olympus E-P3	Four Thirds	12.2	4032	3024	1080/60i	20.8	10.1	536	51
4.		Olympus E-PL1	Four Thirds	12.2	4032	3024	720/30p	21.5	10.1	487	54
5.		Olympus E-PL2	Four Thirds	12.2	4032	3024	720/30p	21.4	10.2	573	55
6.		Olympus E-PL3	Four Thirds	12.2	4032	3024	1080/60i	20.9	10.3	499	52
7.		Olympus E-PL5	Four Thirds	15.9	4608	3456	1080/30p	22.8	12.3	889	72
8.		Olympus E-PM2	Four Thirds	15.9	4608	3456	1080/30p	22.7	12.2	932	72
9.		Panasonic G2	Four Thirds	12.0	4000	3000	720/30p	21.2	10.3	493	53
10.		Panasonic GF2	Four Thirds	12.0	4000	3000	1080/60i	21.2	10.3	506	54
11.		Panasonic GF3	Four Thirds	12.0	4000	3000	1080/60i	20.6	10.1	459	50
12.		Panasonic GF5	Four Thirds	12.0	4000	3000	1080/60i	20.5	10.0	573	50
13.		Sony A7 IV	Full Frame	32.7	7008	4672	4K/60p	25.4	14.7	3379	97
14.		Sony A7R II	Full Frame	42.2	7952	5304	4K/30p	26.0	13.9	3434	98
15.		Sony A7R IV	Full Frame	60.2	9504	6336	4K/30p	26.0	14.8	3344	99
16.		Sony A7S	Full Frame	12.0	4240	2832	1080/60p	23.9	13.2	3702	87
17.		Sony A7S III	Full Frame	12.0	4240	2832	4K/120p	23.7	13.9	2520	86

Many modern cameras are not only capable of taking still images, but can also record movies. The two cameras under consideration both have sensors whose read-out speed is fast enough to capture moving pictures, but the A7S II provides a better video resolution than the E-PM1. It can shoot movie footage at 4K/30p, while the Olympus is limited to 1080/60i.

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. For example, the A7S II 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 A7S II 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 A7S II	2400	n	3.0 / 1229	tilting	n	1/8000s	5.0/s	n	Y
3.		Olympus E-P3	optional	n	3.0 / 614	fixed	Y	1/4000s	3.0/s	Y	Y
4.		Olympus E-PL1	optional	n	2.7 / 230	fixed	n	1/2000s	3.0/s	Y	Y
5.		Olympus E-PL2	optional	n	3.0 / 460	fixed	n	1/4000s	3.0/s	Y	Y
6.		Olympus E-PL3	optional	n	3.0 / 460	tilting	n	1/4000s	5.5/s	n	Y
7.		Olympus E-PL5	optional	n	3.0 / 460	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.		Panasonic G2	1440	n	3.0 / 460	swivel	Y	1/4000s	2.6/s	Y	n
10.		Panasonic GF2	optional	n	3.0 / 460	fixed	Y	1/4000s	2.6/s	Y	n
11.		Panasonic GF3	none	n	3.0 / 460	fixed	Y	1/4000s	3.2/s	Y	n
12.		Panasonic GF5	none	n	3.0 / 920	fixed	Y	1/4000s	4.0/s	Y	n
13.		Sony A7 IV	3686	n	3.0 / 1037	swivel	Y	1/8000s	10.0/s	n	Y
14.		Sony A7R II	2400	n	3.0 / 1229	tilting	n	1/8000s	5.0/s	n	Y
15.		Sony A7R IV	5760	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
16.		Sony A7S	2400	n	3.0 / 921	tilting	n	1/8000s	5.0/s	n	n
17.		Sony A7S III	9440	n	3.0 / 1440	swivel	Y	1/8000s	10.0/s	n	Y
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

The reported shutter speed information refers to the use of the mechanical shutter. Yet, some cameras only have an electronic shutter, while others have an electronic shutter in addition to a mechanical one. In fact, the A7S II is one of those camera that have an additional electronic shutter, which makes completely silent shooting possible. However, this mode is less suitable for photographing moving objects (risk of rolling shutter) or shooting under artificial light sources (risk of flickering).

The E-PM1 writes its imaging data to SDXC cards, while the A7S II uses SDXC or Memory Stick PRO Duo cards. The A7S II 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 7S II 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 A7S II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
3.		Olympus E-P3	Y	stereo / -	-	-	mini	2.0	-	-	-
4.		Olympus E-PL1	Y	stereo / -	-	-	mini	2.0	-	-	-
5.		Olympus E-PL2	Y	stereo / -	-	-	mini	2.0	-	-	-
6.		Olympus E-PL3	Y	stereo / -	-	-	mini	2.0	-	-	-
7.		Olympus E-PL5	Y	stereo / mono	-	-	mini	2.0	-	-	-
8.		Olympus E-PM2	Y	stereo / mono	-	-	mini	2.0	-	-	-
9.		Panasonic G2	Y	stereo / mono	-	-	mini	2.0	-	-	-
10.		Panasonic GF2	Y	stereo / mono	-	-	mini	2.0	-	-	-
11.		Panasonic GF3	-	stereo / mono	-	-	mini	2.0	-	-	-
12.		Panasonic GF5	-	stereo / mono	-	-	mini	2.0	-	-	-
13.		Sony A7 IV	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
14.		Sony A7R II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
15.		Sony A7R IV	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
16.		Sony A7S	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
17.		Sony A7S III	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y

It is notable that the A7S II 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 A7S II have been discontinued, but can regularly be found used on ebay. The E-PM1 was replaced by the Olympus E-PM2, while the A7S II was followed by the Sony A7S III. Further information on the features and operation of the E-PM1 and A7S II can be found, respectively, in the Olympus E-PM1 Manual (free pdf) or the online Sony A7S II Manual.

Review summary

So what is the bottom line? Is there a clear favorite between the Olympus E-PM1 and the Sony A7S II? 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 127x96mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 362g or 58 percent) and hence easier to carry around.
• More affordable: Was introduced into a lower priced category (83 percent cheaper at launch).
• More heavily discounted: Has been available for much longer (launched in June 2011).

Advantages of the Sony Alpha 7S II:

• Better image quality: Scores substantially higher (33 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (2.6 bits more color depth).
• More dynamic range: Captures a broader range of light and dark details (3 EV of extra DR).
• Better low-light sensitivity: Can shoot in dim conditions (2.6 stops ISO advantage).
• Better video: Provides higher definition movie capture (4K/30p vs 1080/60i).
• 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 (1229k 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.
• Less disturbing: Has an electronic shutter option for completely silent shooting.
• Longer lasting: Gets more shots (370 versus 330) out of a single battery charge.
• 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 4 years and 2 months of technical progress since the E-PM1 launch.

If the number of relative strengths (bullet points above) is taken as a guide, the A7S II is the clear winner of the contest (19 : 4 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-PM1 and the Sony A7S II 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 A7S II 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 A7S II	5/5	+	..	..	4.5/5	5/5	Sep 2015	2,999	ebay.com
3.		Olympus E-P3	..	83/100	..	74/100	4.5/5	4.5/5	Jun 2011	799	ebay.com
4.		Olympus E-PL1	..	86/100	..	69/100	4/5	4.5/5	Feb 2010	599	ebay.com
5.		Olympus E-PL2	3/5	83/100	..	71/100	4.5/5	4.5/5	Jan 2011	599	ebay.com
6.		Olympus E-PL3	3/5	+ +	..	72/100	4.5/5	4/5	Jun 2011	599	ebay.com
7.		Olympus E-PL5	3/5	+ +	..	..	4.5/5	4.5/5	Sep 2012	599	ebay.com
8.		Olympus E-PM2	3/5	..	..	77/100	5/5	4.5/5	Sep 2012	499	ebay.com
9.		Panasonic G2	..	..	..	72/100	4/5	4.5/5	Mar 2010	599	ebay.com
10.		Panasonic GF2	3/5	82/100	..	70/100	4.5/5	4.5/5	Nov 2010	549	ebay.com
11.		Panasonic GF3	3/5	82/100	..	71/100	4.5/5	4/5	Jun 2011	549	ebay.com
12.		Panasonic GF5	3/5	..	..	..	4.5/5	4.5/5	Apr 2012	499	ebay.com
13.		Sony A7 IV	5/5	+ +	4.5/5	89/100	4.5/5	4.5/5	Oct 2021	2,499	amazon.com
14.		Sony A7R II	5/5	+ +	5/5	90/100	5/5	5/5	Jun 2015	3,199	ebay.com
15.		Sony A7R IV	5/5	+	4.5/5	91/100	4.5/5	5/5	Jul 2019	3,499	ebay.com
16.		Sony A7S	4/5	..	..	86/100	4.5/5	5/5	Apr 2014	2,499	ebay.com
17.		Sony A7S III	4.5/5	+ +	5/5	91/100	4.5/5	5/5	Jul 2020	3,499	amazon.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The above review scores should be interpreted with care, though. The assessments were made in relation to similar cameras of the same technological generation. A score, therefore, has to be seen in close connection to the price and market introduction time 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

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