Olympus E-M1 III vs OM System OM-3

The Olympus OM-D E-M1 Mark III and the OM System OM-3 are two enthusiast cameras that were officially introduced, respectively, in February 2020 and February 2025. Both the E-M1 III and the OM-3 are mirrorless interchangeable lens cameras that are equipped with a Four Thirds sensor. Both cameras offer a resolution of 20.2 megapixels.

Below is an overview of the main specs of the two cameras as a starting point for the comparison.

Headline Specifications

Olympus E-M1 III		OM System OM-3
Mirrorless system camera		Mirrorless system camera
Micro Four Thirds lenses		Micro Four Thirds lenses
20.2 MP – Four Thirds sensor		20.2 MP – Four Thirds sensor
4K/30p Video		4K/60p Video
ISO 200-25,600		ISO 80-25,600 (80 - 102,400)
Electronic viewfinder (2360k dots)		Electronic viewfinder (2360k dots)
3.0" LCD – 1037k dots		3.0" LCD – 1640k dots
Swivel touchscreen		Swivel touchscreen
18 shutter flaps per second		6 shutter flaps per second
In-body stabilization		In-body stabilization
Weathersealed body		Weathersealed body
420 shots per battery charge		590 shots per battery charge
134 x 91 x 69 mm, 580 g		139 x 89 x 46 mm, 496 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Olympus OM-D E-M1 Mark III and the OM System OM-3? 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-M1 III and the OM System OM-3 are illustrated in the side-by-side display below. The two cameras are presented according to their relative size. Three successive views from the front, the top, and the rear are shown. All width, height and depth dimensions are rounded to the nearest millimeter.

The OM-3 can be obtained in two different colors (black, silver), while the E-M1 III 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 OM System OM-3 is somewhat larger (1 percent) than the Olympus E-M1 III. However, the OM-3 is markedly lighter (14 percent) than the E-M1 III. In this context, it is worth noting that both cameras are splash and dust-proof and can, hence, be used in inclement weather conditions or harsh environments.

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. In this particular case, both cameras feature the same lens mount, so that they can use the same lenses. You can compare the optics available in the Micro Four Thirds Lens Catalog. 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-M1 III gets 420 shots out of its Olympus BLH-1 battery, while the OM-3 can take 590 images on a single charge of its OM System BLX-1 power pack. The battery packs of both cameras can be charged via USB, which can be very convenient when travelling.

The following table provides a synthesis of the main physical specifications of the two cameras and other similar ones. If you would like to visualize and compare a different camera combination, you can navigate to the CAM-parator app and make your selection from a broad list of cameras there.

Body Specifications

		Camera Model	Camera Width	Camera Height	Camera Depth	Camera Weight	Battery Life	Weather Sealing	Camera Launch	Launch Price	Street Price
1.		Olympus E-M1 III	134 mm	91 mm	69 mm	580 g	420	Y	Feb 2020	US$ 1 799	ebay.com
2.		OM System OM-3	139 mm	89 mm	46 mm	496 g	590	Y	Feb 2025	US$ 1 999	amazon.com
3.		Olympus E-M1 II	134 mm	91 mm	67 mm	574 g	440	Y	Sep 2016	US$ 1 999	ebay.com
4.		Olympus E-M1X	144 mm	147 mm	75 mm	997 g	870	Y	Jan 2019	US$ 2 999	ebay.com
5.		Olympus E-M5 III	125 mm	85 mm	50 mm	414 g	310	Y	Oct 2019	US$ 1 199	ebay.com
6.		OM System OM-1	135 mm	92 mm	73 mm	599 g	520	Y	Feb 2022	US$ 2 199	ebay.com
7.		OM System OM-1 II	135 mm	92 mm	73 mm	599 g	500	Y	Jan 2024	US$ 2 399	amazon.com
8.		OM System OM-5 II	125 mm	85 mm	50 mm	414 g	310	Y	Jun 2025	US$ 1 199	amazon.com
9.		Panasonic G9	137 mm	97 mm	92 mm	658 g	400	Y	Nov 2017	US$ 1 699	ebay.com
10.		Panasonic G97	130 mm	94 mm	77 mm	536 g	290	Y	Apr 2019	US$ 749	ebay.com
11.		Panasonic G95	130 mm	94 mm	77 mm	536 g	290	Y	Apr 2019	US$ 999	ebay.com
12.		Panasonic GH5	139 mm	98 mm	87 mm	725 g	410	Y	Jan 2017	US$ 1 999	ebay.com
13.		Panasonic GH5 II	139 mm	98 mm	87 mm	727 g	400	Y	May 2021	US$ 1 699	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 obviously take relative prices into account. The listed launch prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The E-M1 III was somewhat cheaper (by 10 percent) than the OM-3 at launch, but both cameras fall into the same price category. 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.

Sensor comparison

The size of the imaging sensor is a crucial determinant 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. 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.

Both cameras under consideration feature a Four Thirds sensor and have a format factor (sometimes also referred to as "crop factor") of 2.0. Within the spectrum of camera sensors, this places the review cameras among the medium-sized sensor cameras that aim to strike a balance between image quality and portability. Both cameras feature a native aspect ratio (sensor width to sensor height) of 4:3.

Technology-wise, the OM-3 uses a more advanced image processing engine (TruePic X) than the E-M1 III (TruePic IX), with benefits for noise reduction, color accuracy, and processing speed.

The two cameras under review do not only share the same sensor size, but also offer an identical resolution of 20.2 megapixels. This similarity in sensor specs implies that both the E-M1 III and the OM-3 have the same pixel density, as well as the same pixel size. It should, however, be noted that the OM-3 is much more recent (by 4 years and 11 months) than the E-M1 III, and its sensor will have benefitted from technological advances during this time. Coming back to sensor resolution, it should be mentioned that neither of the two cameras has an anti-alias filter installed, so they are able to capture all the detail the sensor resolves.

Both cameras have the capacity to capture high quality composite images by combining multiple shots after shifting the sensor by miniscule distances. This multi-shot, pixel-shift mode is most suitable for photography of stationary objects (landscapes, studio scenes).

The Olympus OM-D E-M1 Mark III has a native sensitivity range from ISO 200 to ISO 25600, which can be extended to ISO 64-25600. The corresponding ISO settings for the OM System OM-3 are ISO 80 to ISO 25600, with the possibility to increase the ISO range to 80-102400.

In terms of underlying technology, the E-M1 III is build around a CMOS sensor, while the OM-3 uses a Stacked BSI-CMOS imager. 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 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"). 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-M1 III	Four Thirds	20.2	5184	3888	4K/30p	23.3	13.1	1356	76
2.		OM System OM-3	Four Thirds	20.2	5184	3888	4K/60p	23.4	13.7	1852	78
3.		Olympus E-M1 II	Four Thirds	20.2	5184	3888	4K/30p	23.7	12.8	1312	80
4.		Olympus E-M1X	Four Thirds	20.2	5184	3888	4K/30p	23.2	13.0	1254	75
5.		Olympus E-M5 III	Four Thirds	20.2	5184	3888	4K/30p	23.3	13.1	1324	76
6.		OM System OM-1	Four Thirds	20.2	5184	3888	4K/60p	23.4	13.4	1553	77
7.		OM System OM-1 II	Four Thirds	20.2	5184	3888	4K/60p	23.4	13.6	1749	78
8.		OM System OM-5 II	Four Thirds	20.2	5184	3888	4K/30p	23.4	13.7	1889	78
9.		Panasonic G9	Four Thirds	20.2	5184	3888	4K/60p	23.1	12.8	1138	74
10.		Panasonic G97	Four Thirds	20.2	5184	3888	4K/30p	23.2	13.0	1273	75
11.		Panasonic G95	Four Thirds	20.2	5184	3888	4K/30p	23.2	13.0	1273	75
12.		Panasonic GH5	Four Thirds	20.2	5184	3888	4K/60p	23.9	13.0	807	77
13.		Panasonic GH5 II	Four Thirds	20.2	5184	3888	4K/60p	23.7	13.1	1136	79
Note: DXO values in italics represent estimates based on sensor size and age.

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 OM-3 provides a faster frame rate than the E-M1 III. It can shoot movie footage at 4K/60p, while the Olympus is limited to 4K/30p.

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. The E-M1 III and the OM-3 are similar in the sense that both feature an electronic viewfinder, which is helpful when framing images in bright sunlight. Moreover, their viewfinders offer an identical resolution of 2360k dots. The adjacent table lists some of the other core features of the Olympus E-M1 III and OM System OM-3 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-M1 III	2360	n	3.0 / 1037	swivel	Y	1/8000s	18.0/s	n	Y
2.		OM System OM-3	2360	n	3.0 / 1640	swivel	Y	1/8000s	6.0/s	n	Y
3.		Olympus E-M1 II	2360	n	3.0 / 1037	swivel	Y	1/8000s	18.0/s	n	Y
4.		Olympus E-M1X	2360	n	3.0 / 1037	swivel	Y	1/8000s	18.0/s	n	Y
5.		Olympus E-M5 III	2360	n	3.0 / 1040	swivel	Y	1/8000s	10.0/s	n	Y
6.		OM System OM-1	5760	n	3.0 / 1640	swivel	Y	1/8000s	10.0/s	n	Y
7.		OM System OM-1 II	5760	n	3.0 / 1640	swivel	Y	1/8000s	10.0/s	n	Y
8.		OM System OM-5 II	2360	n	3.0 / 1040	swivel	Y	1/8000s	10.0/s	n	Y
9.		Panasonic G9	3680	Y	3.0 / 1040	swivel	Y	1/8000s	20.0/s	n	Y
10.		Panasonic G97	2360	n	3.0 / 1840	swivel	Y	1/4000s	9.0/s	Y	Y
11.		Panasonic G95	2360	n	3.0 / 1240	swivel	Y	1/4000s	9.0/s	Y	Y
12.		Panasonic GH5	3680	n	3.2 / 1620	swivel	Y	1/8000s	12.0/s	n	Y
13.		Panasonic GH5 II	3680	n	3.0 / 1840	swivel	Y	1/8000s	12.0/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, both cameras under consideration feature an 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 Olympus E-M1 III and the OM System OM-3 both have 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.

Concerning the storage of imaging data, both the E-M1 III and the OM-3 write their files to SDXC cards. The E-M1 III features dual card slots, which can be very useful in case a memory card fails. In contrast, the OM-3 only has one slot. Both cameras support UHS-II cards, which provide for Ultra High Speed data transfer of up to 312 MB/s (the second slot of the E-M1 III supports only UHS-I, though).

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-M1 Mark III and OM System OM-3 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-M1 III	Y	stereo / mono	Y	Y	micro	3.1	Y	-	Y
2.		OM System OM-3	Y	stereo / mono	Y	Y	micro	3.0	Y	-	Y
3.		Olympus E-M1 II	Y	stereo / mono	Y	Y	micro	3.0	Y	-	-
4.		Olympus E-M1X	Y	stereo / mono	Y	Y	micro	3.0	Y	-	Y
5.		Olympus E-M5 III	Y	stereo / mono	Y	-	micro	2.0	Y	-	Y
6.		OM System OM-1	Y	stereo / mono	Y	Y	micro	3.0	Y	-	Y
7.		OM System OM-1 II	Y	stereo / mono	Y	Y	micro	3.0	Y	-	Y
8.		OM System OM-5 II	Y	stereo / mono	Y	-	micro	2.0	Y	-	Y
9.		Panasonic G9	Y	stereo / mono	Y	Y	full	3.0	Y	-	Y
10.		Panasonic G97	Y	stereo / mono	Y	Y	micro	2.0	Y	-	Y
11.		Panasonic G95	Y	stereo / mono	Y	Y	micro	2.0	Y	-	Y
12.		Panasonic GH5	Y	stereo / mono	Y	Y	full	3.1	Y	-	Y
13.		Panasonic GH5 II	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y

Studio photographers will appreciate that the Olympus E-M1 III (unlike the OM-3) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

The OM-3 is a recent model that features in the current product line-up of OM System. In contrast, the E-M1 III has been discontinued (but can be found pre-owned on ebay). As a replacement in the same line of cameras, the E-M1 III was succeeded by the OM System OM-1. Further information on the two cameras (e.g. user guides, manuals), as well as related accessories, can be found on the official Olympus and OM System websites.

Review summary

So how do things add up? Is there a clear favorite between the Olympus E-M1 III and the OM System OM-3? Which camera is better? The listing below highlights the relative strengths of the two models.

Arguments in favor of the Olympus OM-D E-M1 Mark III:

• Larger viewfinder image: Features a viewfinder with a higher magnification (0.74x vs 0.69x).
• Faster burst: Shoots at higher frequency (18 vs 6 flaps/sec) to capture the decisive moment.
• Better studio light control: Has a PC Sync socket to connect to professional strobe lights.
• Greater peace of mind: Features a second card slot as a backup in case of memory card failure.
• More heavily discounted: Has been available for much longer (launched in February 2020).

Advantages of the OM System OM-3:

• Better jpgs: Has a more modern image processing engine (TruePic X vs TruePic IX).
• Better video: Provides higher movie framerates (4K/60p versus 4K/30p).
• More detailed LCD: Has a higher resolution rear screen (1640k vs 1037k dots).
• Less heavy: Has a lower weight (by 84g or 14 percent) and is thus easier to take along.
• Longer lasting: Gets more shots (590 versus 420) out of a single battery charge.
• More modern: Reflects 4 years and 11 months of technical progress since the E-M1 III launch.

If the number of relative strengths (bullet points above) is taken as a guide, the OM-3 comes out slightly ahead of the E-M1 III (6 : 5 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 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-M1 III and the OM System OM-3 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 remains partial and cannot reveal, for example, the shooting experience and imaging performance when actually working with the E-M1 III or the OM-3. At times, user reviews, such as those published at amazon, address these issues in a useful manner, but such feedback is on many occasions incomplete, inconsistent, and unreliable.

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	Street Price
1.		Olympus E-M1 III	5/5	..	5/5	83/100	4.5/5	4/5	Feb 2020	US$ 1 799	ebay.com
2.		OM System OM-3	..	..	..	86/100	..	..	Feb 2025	US$ 1 999	amazon.com
3.		Olympus E-M1 II	5/5	+ +	5/5	85/100	4.5/5	4.5/5	Sep 2016	US$ 1 999	ebay.com
4.		Olympus E-M1X	4.5/5	o	5/5	85/100	4.5/5	..	Jan 2019	US$ 2 999	ebay.com
5.		Olympus E-M5 III	5/5	+	5/5	82/100	4.5/5	4.5/5	Oct 2019	US$ 1 199	ebay.com
6.		OM System OM-1	5/5	..	..	87/100	5/5	4.5/5	Feb 2022	US$ 2 199	ebay.com
7.		OM System OM-1 II	..	..	..	..	..	..	Jan 2024	US$ 2 399	amazon.com
8.		OM System OM-5 II	..	..	..	..	..	..	Jun 2025	US$ 1 199	amazon.com
9.		Panasonic G9	..	+ +	5/5	85/100	5/5	5/5	Nov 2017	US$ 1 699	ebay.com
10.		Panasonic G97	..	..	..	..	..	..	Apr 2019	US$ 749	ebay.com
11.		Panasonic G95	4.5/5	+	4.5/5	83/100	4.5/5	4.5/5	Apr 2019	US$ 999	ebay.com
12.		Panasonic GH5	4.5/5	+ +	..	85/100	4.5/5	5/5	Jan 2017	US$ 1 999	ebay.com
13.		Panasonic GH5 II	4.5/5	..	4.5/5	85/100	4.5/5	5/5	May 2021	US$ 1 699	amazon.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. Hence, a score should always be seen in the context of the camera's market launch date and its price, and comparisons of ratings among very different cameras or across long time periods have little meaning. 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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