Olympus E-M1 III vs OM System OM-1

The Olympus OM-D E-M1 Mark III and the OM System OM-1 are two enthusiast cameras that were announced, respectively, in February 2020 and February 2022. Both the E-M1 III and the OM-1 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-1
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 (5760k dots)
3.0" LCD – 1037k dots		3.0" LCD – 1640k dots
Swivel touchscreen		Swivel touchscreen
18 shutter flaps per second		10 shutter flaps per second
In-body stabilization		In-body stabilization
Weathersealed body		Weathersealed body
420 shots per battery charge		520 shots per battery charge
134 x 91 x 69 mm, 580 g		135 x 92 x 73 mm, 599 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-1? 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-M1 III and the OM System OM-1 is provided 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 width, height and depth dimensions are rounded to the nearest millimeter.

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the OM System OM-1 is somewhat larger (2 percent) than the Olympus E-M1 III. Moreover, the OM-1 is slightly heavier (3 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-1 can take 520 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 adjacent table lists the principal physical characteristics of the two cameras alongside a wider set of alternatives. 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 (USD)	Street Price
1.		Olympus E-M1 III	134 mm	91 mm	69 mm	580 g	420	Y	Feb 2020	1,799	ebay.com
2.		OM System OM-1	135 mm	92 mm	73 mm	599 g	520	Y	Feb 2022	2,199	ebay.com
3.		Olympus E-M5 III	125 mm	85 mm	50 mm	414 g	310	Y	Oct 2019	1,199	ebay.com
4.		Olympus E-M1X	144 mm	147 mm	75 mm	997 g	870	Y	Jan 2019	2,999	ebay.com
5.		Olympus E-M1 II	134 mm	91 mm	67 mm	574 g	440	Y	Sep 2016	1,999	ebay.com
6.		Olympus E-M1	130 mm	94 mm	63 mm	497 g	350	Y	Sep 2013	1,399	ebay.com
7.		OM System OM-1 II	135 mm	92 mm	73 mm	599 g	500	Y	Jan 2024	2,399	amazon.com
8.		Panasonic GH5 II	139 mm	98 mm	87 mm	727 g	400	Y	May 2021	1,699	amazon.com
9.		Panasonic G95	130 mm	94 mm	77 mm	536 g	290	Y	Apr 2019	999	ebay.com
10.		Panasonic G9	137 mm	97 mm	92 mm	658 g	400	Y	Nov 2017	1,699	ebay.com
11.		Panasonic GH5	139 mm	98 mm	87 mm	725 g	410	Y	Jan 2017	1,999	ebay.com
12.		Panasonic GX8	133 mm	78 mm	63 mm	487 g	330	Y	Jul 2015	1,199	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 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-M1 III was launched at a somewhat lower price (by 18 percent) than the OM-1, which makes it more attractive for photographers on a tight budget. 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 imaging sensor is a crucial determinant 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. 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.

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-1 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-1 have the same pixel density, as well as the same pixel size. It should, however, be noted that the OM-1 is much more recent (by 2 years) 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-1 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-1 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.

Since 2007, DXO Mark has published sensor performance measurements that have been derived using a consistent methodology. 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 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-M1 III	Four Thirds	20.2	5184	3888	4K/30p	23.3	13.1	1356	76
2.		OM System OM-1	Four Thirds	20.2	5184	3888	4K/60p	23.4	13.4	1553	77
3.		Olympus E-M5 III	Four Thirds	20.2	5184	3888	4K/30p	23.3	13.1	1324	76
4.		Olympus E-M1X	Four Thirds	20.2	5184	3888	4K/30p	23.2	13.0	1254	75
5.		Olympus E-M1 II	Four Thirds	20.2	5184	3888	4K/30p	23.7	12.8	1312	80
6.		Olympus E-M1	Four Thirds	15.9	4608	3456	1080/30p	23.0	12.7	757	73
7.		OM System OM-1 II	Four Thirds	20.2	5184	3888	4K/60p	23.4	13.6	1749	78
8.		Panasonic GH5 II	Four Thirds	20.2	5184	3888	4K/60p	23.7	13.1	1136	79
9.		Panasonic G95	Four Thirds	20.2	5184	3888	4K/30p	23.2	13.0	1273	75
10.		Panasonic G9	Four Thirds	20.2	5184	3888	4K/60p	23.1	12.8	1138	74
11.		Panasonic GH5	Four Thirds	20.2	5184	3888	4K/60p	23.9	13.0	807	77
12.		Panasonic GX8	Four Thirds	20.2	5184	3888	4K/30p	23.5	12.6	806	75
Note: DXO values in italics represent estimates based on sensor size and age.

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 OM-1 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

Apart from body and sensor, cameras can and do differ across a range of features. The two cameras under review are similar with respect to both having an electronic viewfinder. However, the one in the OM-1 offers a substantially higher resolution than the one in the E-M1 III (5760k vs 2360k dots). The adjacent table lists some of the other core features of the Olympus E-M1 III and OM System OM-1 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-1	5760	n	3.0 / 1640	swivel	Y	1/8000s	10.0/s	n	Y
3.		Olympus E-M5 III	2360	n	3.0 / 1040	swivel	Y	1/8000s	10.0/s	n	Y
4.		Olympus E-M1X	2360	n	3.0 / 1037	swivel	Y	1/8000s	18.0/s	n	Y
5.		Olympus E-M1 II	2360	n	3.0 / 1037	swivel	Y	1/8000s	18.0/s	n	Y
6.		Olympus E-M1	2360	n	3.0 / 1037	tilting	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.		Panasonic GH5 II	3680	n	3.0 / 1840	swivel	Y	1/8000s	12.0/s	n	Y
9.		Panasonic G95	2360	n	3.0 / 1240	swivel	Y	1/4000s	9.0/s	Y	Y
10.		Panasonic G9	3680	Y	3.0 / 1040	swivel	Y	1/8000s	20.0/s	n	Y
11.		Panasonic GH5	3680	n	3.2 / 1620	swivel	Y	1/8000s	12.0/s	n	Y
12.		Panasonic GX8	2360	n	3.0 / 1040	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, 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-1 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-1 write their files to SDXC cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails. However, while the OM-1 supports UHS-II cards (Ultra High Speed data transfer of up to 312 MB/s) on both slots, the E-M1 III supports UHS-II only on its first slot and UHS-I (data transfer speed up to 104 MB/s) on the second one.

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-1 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-1	Y	stereo / mono	Y	Y	micro	3.0	Y	-	Y
3.		Olympus E-M5 III	Y	stereo / mono	Y	-	micro	2.0	Y	-	Y
4.		Olympus E-M1X	Y	stereo / mono	Y	Y	micro	3.0	Y	-	Y
5.		Olympus E-M1 II	Y	stereo / mono	Y	Y	micro	3.0	Y	-	-
6.		Olympus E-M1	Y	stereo / mono	Y	-	micro	2.0	Y	-	-
7.		OM System OM-1 II	Y	stereo / mono	Y	Y	micro	3.0	Y	-	Y
8.		Panasonic GH5 II	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
9.		Panasonic G95	Y	stereo / mono	Y	Y	micro	2.0	Y	-	Y
10.		Panasonic G9	Y	stereo / mono	Y	Y	full	3.0	Y	-	Y
11.		Panasonic GH5	Y	stereo / mono	Y	Y	full	3.1	Y	-	Y
12.		Panasonic GX8	Y	stereo / mono	Y	-	micro	2.0	Y	Y	-

Both cameras feature a PC Sync terminal to control professional strobe lights, which will be appreciated by studio photographers.

Both the E-M1 III and the OM-1 have been discontinued, but can regularly be found used on ebay. The E-M1 III was replaced by the OM System OM-1, while the OM-1 was followed by the OM System OM-1 II. Further information on the features and operation of the E-M1 III and OM-1 can be found, respectively, in the Olympus E-M1 III Manual (free pdf) or the online OM System OM-1 Manual.

Review summary

So what conclusions can be drawn? Is the Olympus E-M1 III better than the OM System OM-1 or vice versa? Below is a summary of the relative strengths of each of the two contestants.

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

• Faster burst: Shoots at higher frequency (18 vs 10 flaps/sec) to capture the decisive moment.
• More affordable: Was introduced into a lower priced segment (18 percent cheaper at launch).
• More heavily discounted: Has been available for much longer (launched in February 2020).

Advantages of the OM System OM-1:

• 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 viewfinder: Has higher resolution electronic viewfinder (5760k vs 2360k dots).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.82x vs 0.74x).
• More detailed LCD: Has a higher resolution rear screen (1640k vs 1037k dots).
• Longer lasting: Gets more shots (520 versus 420) out of a single battery charge.
• More modern: Reflects 2 years of technical progress since the E-M1 III launch.

If the count of individual advantages (bullet points above) is taken as a guide, the OM-1 is the clear winner of the contest (7 : 3 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-M1 III and the OM System OM-1 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-M1 III and the OM-1 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 expert reviews 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-M1 III	5/5	..	5/5	83/100	4.5/5	4/5	Feb 2020	1,799	ebay.com
2.		OM System OM-1	5/5	..	..	87/100	5/5	4.5/5	Feb 2022	2,199	ebay.com
3.		Olympus E-M5 III	5/5	+	5/5	82/100	4.5/5	4.5/5	Oct 2019	1,199	ebay.com
4.		Olympus E-M1X	4.5/5	o	5/5	85/100	4.5/5	..	Jan 2019	2,999	ebay.com
5.		Olympus E-M1 II	5/5	+ +	5/5	85/100	4.5/5	4.5/5	Sep 2016	1,999	ebay.com
6.		Olympus E-M1	5/5	+ +	..	84/100	4.5/5	4.5/5	Sep 2013	1,399	ebay.com
7.		OM System OM-1 II	..	..	..	..	..	..	Jan 2024	2,399	amazon.com
8.		Panasonic GH5 II	4.5/5	..	4.5/5	85/100	4.5/5	5/5	May 2021	1,699	amazon.com
9.		Panasonic G95	4.5/5	+	4.5/5	83/100	4.5/5	4.5/5	Apr 2019	999	ebay.com
10.		Panasonic G9	..	+ +	5/5	85/100	5/5	5/5	Nov 2017	1,699	ebay.com
11.		Panasonic GH5	4.5/5	+ +	..	85/100	4.5/5	5/5	Jan 2017	1,999	ebay.com
12.		Panasonic GX8	5/5	+	..	82/100	4.5/5	4.5/5	Jul 2015	1,199	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The review scores listed above should be treated 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. Thus, a score needs to be put into the context of the launch date and the launch price of the camera, and comparisons of ratings among very different cameras or across long time periods 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? If you would like to see a different side-by-side camera review, just make a corresponding selection in the search boxes below. Alternatively, you can follow any of the listed hyperlinks for comparisons that others found interesting.

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