Olympus E-PM1 vs Sony RX100

The Olympus PEN E-PM1 and the Sony Cyber-shot DSC-RX100 are two digital cameras that were officially introduced, respectively, in June 2011 and June 2012. The E-PM1 is a mirrorless interchangeable lens camera, while the RX100 is a fixed lens compact. The cameras are based on a Four Thirds (E-PM1) and an one-inch (RX100) sensor. The Olympus has a resolution of 12.2 megapixels, whereas the Sony provides 20 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 RX100
Mirrorless system camera		Fixed lens compact camera
Micro Four Thirds lenses		28-100mm f/1.8-4.9
12.2 MP – Four Thirds sensor		20 MP – 1" sensor
1080/60i Video		1080/60p Video
ISO 100-12,800		ISO 100-6,400 (100 - 25,600)
Viewfinder optional		No viewfinder, LCD framing
3.0" LCD – 460k dots		3.0" LCD – 1229k dots
Fixed screen (not touch-sensitive)		Fixed screen (not touch-sensitive)
5.5 shutter flaps per second		10 shutter flaps per second
In-body stabilization		Lens-based stabilization
330 shots per battery charge		330 shots per battery charge
110 x 64 x 34 mm, 265 g		102 x 58 x 36 mm, 240 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 Cyber-shot DSC-RX100? 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-PM1 and the Sony RX100 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-PM1 can be obtained in six different colors (black, silver, brown, pink, purple, white), while the RX100 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 RX100 is notably smaller (16 percent) than the Olympus E-PM1. In this context, it is worth noting that neither the E-PM1 nor the RX100 are weather-sealed.

The above size and weight comparisons are to some extent incomplete and possibly misleading, as the RX100 has a lens built in, whereas the E-PM1 is an interchangeable lens camera that requires a separate lens. Attaching the latter will add extra weight and bulk to the setup. You can compare the optics available for the E-PM1 and their specifications in the Micro Four Thirds Lens Catalog.

The power pack in the RX100 can be charged via the USB port, which can be very convenient when travelling.

The adjacent table lists the principal physical characteristics of the two cameras alongside a wider set of alternatives. 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 RX100	102 mm	58 mm	36 mm	240 g	330	n	Jun 2012	649	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-PM2	110 mm	64 mm	34 mm	269 g	360	n	Sep 2012	499	ebay.com
8.		Olympus XZ-1	111 mm	65 mm	42 mm	275 g	320	n	Jan 2011	499	ebay.com
9.		Olympus XZ-2	113 mm	65 mm	48 mm	346 g	340	n	Sep 2012	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 A5100	110 mm	63 mm	36 mm	283 g	400	n	Aug 2014	549	ebay.com
14.		Sony NEX-5N	111 mm	59 mm	38 mm	269 g	460	n	Aug 2011	699	ebay.com
15.		Sony NEX-5R	111 mm	59 mm	39 mm	276 g	330	n	Aug 2012	749	ebay.com
16.		Sony RX100 II	102 mm	58 mm	38 mm	281 g	350	n	Jun 2013	749	ebay.com
17.		Sony RX100 III	102 mm	58 mm	41 mm	290 g	320	n	May 2014	799	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 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. 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 size of the sensor inside a digital camera is one of the key determinants 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. Furthermore, a large sensor camera will give the photographer more possibilities to use shallow depth-of-field in order to isolate a subject from the 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 RX100 an one-inch sensor. The sensor area in the RX100 is 48 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 2.0 and 2.7. The sensor in the E-PM1 has a native 4:3 aspect ratio, while the one in the RX100 offers a 3:2 aspect.

Despite having a smaller sensor, the RX100 offers a higher resolution of 20 megapixels, compared with 12.2 MP of the E-PM1. 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 2.41μm versus 4.29μm for the E-PM1). However, it should be noted that the RX100 is a somewhat more recent model (by 11 months) than the E-PM1, and its sensor might have benefitted from technological advances during this time that partly offset its pixel-size disadvantage.

The resolution advantage of the Sony RX100 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the RX100 for good quality output (200 dots per inch) amounts to 27.4 x 18.2 inches or 69.5 x 46.3 cm, for very good quality (250 dpi) 21.9 x 14.6 inches or 55.6 x 37.1 cm, and for excellent quality (300 dpi) 18.2 x 12.2 inches or 46.3 x 30.9 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 Olympus PEN E-PM1 has a native sensitivity range from ISO 100 to ISO 12800. The corresponding ISO settings for the Sony Cyber-shot DSC-RX100 are ISO 100 to ISO 6400, with the possibility to increase the ISO range to 100-25600.

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 RX100 offers substantially better image quality than the E-PM1 (overall score 14 points higher). The advantage is based on 1.6 bits higher color depth, 2.1 EV in additional dynamic range, and 0.4 stops of reduced 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.		Olympus E-PM1	Four Thirds	12.2	4032	3024	1080/60i	21.0	10.3	499	52
2.		Sony RX100	1-inch	20.0	5472	3648	1080/60p	22.6	12.4	390	66
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-PM2	Four Thirds	15.9	4608	3456	1080/30p	22.7	12.2	932	72
8.		Olympus XZ-1	1/1.7	10.1	3664	2752	720/30p	18.8	10.4	117	34
9.		Olympus XZ-2	1/1.7	11.8	3968	2976	1080/30p	20.4	11.3	216	49
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 A5100	APS-C	24.0	6000	4000	1080/60p	23.8	12.7	1347	80
14.		Sony NEX-5N	APS-C	16.0	4912	3264	1080/60i	23.6	12.7	1079	77
15.		Sony NEX-5R	APS-C	16.0	4912	3264	1080/60i	23.7	13.1	910	78
16.		Sony RX100 II	1-inch	20.0	5472	3648	1080/60p	22.5	12.4	483	67
17.		Sony RX100 III	1-inch	20.0	5472	3648	1080/60p	22.4	12.3	495	67

Many modern cameras are not only capable of taking still images, but also of capturing video footage. Both cameras under consideration have a sensor with sufficiently fast read-out times for moving pictures, but the RX100 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. The E-PM1 and the RX100 are similar in the sense that neither of the two has a viewfinder. The images are, thus, framed using live view on the rear LCD. That said, the E-PM1 can be equipped with an optional viewfinder – the VF-2. The adjacent table lists some of the other core features of the Olympus E-PM1 and Sony RX100 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-PM1	optional	n	3.0 / 460	fixed	n	1/4000s	5.5/s	n	Y
2.		Sony RX100	none	n	3.0 / 1229	fixed	n	1/2000s	10.0/s	Y	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-PM2	optional	n	3.0 / 460	fixed	Y	1/4000s	8.0/s	n	Y
8.		Olympus XZ-1	optional	n	3.0 / 614	fixed	n	1/2000s	2.0/s	Y	Y
9.		Olympus XZ-2	optional	n	3.0 / 920	tilting	Y	1/2000s	5.0/s	Y	Y
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 A5100	none	n	3.0 / 922	tilting	Y	1/4000s	6.0/s	Y	n
14.		Sony NEX-5N	optional	n	3.0 / 920	tilting	Y	1/4000s	10.0/s	n	n
15.		Sony NEX-5R	optional	n	3.0 / 920	tilting	Y	1/4000s	10.0/s	n	n
16.		Sony RX100 II	optional	n	3.0 / 1229	tilting	n	1/2000s	10.0/s	Y	Y
17.		Sony RX100 III	1440	n	3.0 / 1229	tilting	n	1/2000s	10.0/s	Y	Y
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 RX100 has one, while the E-PM1 does not. While the built-in flash of the RX100 is not very powerful, it can at times be useful as a fill-in light.

The E-PM1 writes its imaging data to SDXC cards, while the RX100 uses SDXC or Memory Stick PRO Duo 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 Cyber-shot DSC-RX100 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 RX100	-	stereo / mono	-	-	micro	2.0	-	-	-
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-PM2	Y	stereo / mono	-	-	mini	2.0	-	-	-
8.		Olympus XZ-1	Y	mono / -	-	-	mini	2.0	-	-	-
9.		Olympus XZ-2	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 A5100	-	stereo / mono	-	-	micro	2.0	Y	Y	-
14.		Sony NEX-5N	Y	stereo / mono	-	-	mini	2.0	-	-	-
15.		Sony NEX-5R	Y	stereo / mono	-	-	mini	2.0	Y	-	-
16.		Sony RX100 II	Y	stereo / mono	-	-	micro	2.0	Y	Y	-
17.		Sony RX100 III	-	stereo / mono	-	-	micro	2.0	Y	Y	-

It is notable that the E-PM1 has a hotshoe, while the RX100 does not. This socket makes it possible to easily attach optional accessories, such as an external flash gun.

Both the E-PM1 and the RX100 have been discontinued, but can regularly be found used on ebay. The E-PM1 was replaced by the Olympus E-PM2, while the RX100 was followed by the Sony RX100 II. Further information on the features and operation of the E-PM1 and RX100 can be found, respectively, in the Olympus E-PM1 Manual (free pdf) or the online Sony RX100 Manual.

Review summary

So how do things add up? Which of the two cameras – the Olympus E-PM1 or the Sony RX100 – has the upper hand? Is one clearly better than the other? Below is a summary of the relative strengths of each of the two contestants.

Advantages of the Olympus PEN E-PM1:

• Better low-light sensitivity: Requires less light for good images (0.4 stops ISO advantage).
• More framing options: Can be equipped with a hotshoe-mounted accessory-viewfinder.
• Faster shutter: Has higher mechanical shutter speed (1/4000s vs 1/2000s) to freeze action.
• More flexible: Accepts interchangeable lenses, so that lens characteristics can be altered.
• Better lighting: Features a hotshoe and can thus hold and trigger an external flash gun.
• More heavily discounted: Has been on the market for longer (launched in June 2011).

Arguments in favor of the Sony Cyber-shot DSC-RX100:

• More detail: Has more megapixels (20 vs 12.2MP), which boosts linear resolution by 30%.
• Better image quality: Scores substantially higher (14 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (1.6 bits more color depth).
• More dynamic range: Captures a broader range of light and dark details (2.1 EV of extra DR).
• Better video: Provides higher movie framerates (1080/60p versus 1080/60i).
• More detailed LCD: Has a higher resolution rear screen (1229k vs 460k dots).
• Faster burst: Shoots at higher frequency (10 vs 5.5 flaps/sec) to capture the decisive moment.
• Ready to shoot: Has an integrated lens, whereas the E-PM1 necessitates an extra lens.
• More compact: Is smaller (102x58mm vs 110x64mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight even though it has a lens built in (unlike the E-PM1).
• 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.
• More modern: Was introduced somewhat (11 months) more recently.

If the number of relative strengths (bullet points above) is taken as a guide, the RX100 is the clear winner of the contest (13 : 6 points). However, the relative importance of the various individual camera aspects will vary according to personal preferences and needs, so that you might like to apply corresponding weights to the particular features before making a decision on a new camera. A professional sports photographer will view the differences between cameras in a way that diverges from the perspective of a street photog, and a person interested in family portraits has distinct needs from a landscape 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 RX100 place the cameras among the top in their class? Find out in the latest Best Mirrorless Interchangeable Lens Camera and Best Travel-Zoom 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 remains incomplete and does no justice, for example, to the way the E-PM1 or the RX100 perform in practice. 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 where reviews by experts come in. 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 RX100	5/5	+ +	..	78/100	4/5	5/5	Jun 2012	649	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-PM2	3/5	..	..	77/100	5/5	4.5/5	Sep 2012	499	ebay.com
8.		Olympus XZ-1	4/5	..	..	74/100	4.5/5	4.5/5	Jan 2011	499	ebay.com
9.		Olympus XZ-2	4/5	+	..	..	4.5/5	4.5/5	Sep 2012	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 A5100	4.5/5	+	..	..	4.5/5	5/5	Aug 2014	549	ebay.com
14.		Sony NEX-5N	3/5	+ +	..	79/100	4.5/5	4.5/5	Aug 2011	699	ebay.com
15.		Sony NEX-5R	..	..	..	..	4.5/5	4.5/5	Aug 2012	749	ebay.com
16.		Sony RX100 II	5/5	+ +	..	79/100	4.5/5	4.5/5	Jun 2013	749	ebay.com
17.		Sony RX100 III	5/5	+ +	..	82/100	4.5/5	5/5	May 2014	799	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

Care should be taken when interpreting the review scores above, 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 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

Did this review help to inform your camera decision process? In case you are interested in seeing how other cameras pair up, just make a corresponding selection in the search boxes below. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored.

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