OM System OM-3 vs Sony A1 II

The OM System OM-3 and the Sony A1 II are two digital cameras that were announced, respectively, in February 2025 and November 2024. Both the OM-3 and the A1 II are mirrorless interchangeable lens cameras that are based on a Four Thirds (OM-3) and a full frame (A1 II) sensor. The OM System has a resolution of 20.2 megapixels, whereas the Sony provides 49.8 MP.

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

Headline Specifications

OM System OM-3		Sony A1 II
Mirrorless system camera		Mirrorless system camera
Micro Four Thirds lenses		Sony E mount lenses
20.2 MP – Four Thirds sensor		49.8 MP – Full Frame sensor
4K/60p Video		8k/30p Video
ISO 80-25,600 (80 - 102,400)		ISO 100-32,000 (50 - 102,400)
Electronic viewfinder (2360k dots)		Electronic viewfinder (9437k dots)
3.0" LCD – 1640k dots		3.2" LCD – 2100k dots
Swivel touchscreen		Fully flexible touchscreen
6 shutter flaps per second		30 shutter flaps per second
In-body stabilization		In-body stabilization
Weathersealed body		Weathersealed body
590 shots per battery charge		520 shots per battery charge
139 x 89 x 46 mm, 496 g		136 x 97 x 83 mm, 743 g

Check OM-3 price at
amazon.com
Check A1 II price at
amazon.com

Going beyond this snapshot of core features and characteristics, what are the differences between the OM System OM-3 and the Sony A1 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 physical size and weight of the OM System OM-3 and the Sony A1 II are illustrated 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 OM-3 can be obtained in two different colors (black, silver), while the A1 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 A1 II is notably larger (7 percent) than the OM System OM-3. Moreover, the A1 II is substantially heavier (50 percent) than the OM-3. 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. 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 (OM-3) and the Sony FE Lens Catalog (A1 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 OM-3 gets 590 shots out of its OM System BLX-1 battery, while the A1 II can take 520 images on a single charge of its Sony NP-FZ100 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. 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	Street Price
1.		OM System OM-3	139 mm	89 mm	46 mm	496 g	590	Y	Feb 2025	US$ 1 999	amazon.com
2.		Sony A1 II	136 mm	97 mm	83 mm	743 g	520	Y	Nov 2024	US$ 6 499	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-M1 III	134 mm	91 mm	69 mm	580 g	420	Y	Feb 2020	US$ 1 799	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	125 mm	85 mm	50 mm	414 g	310	Y	Oct 2022	US$ 1 199	amazon.com
9.		OM System OM-5 II	125 mm	85 mm	50 mm	414 g	310	Y	Jun 2025	US$ 1 199	amazon.com
10.		Panasonic G9	137 mm	97 mm	92 mm	658 g	400	Y	Nov 2017	US$ 1 699	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.		Sony A1	129 mm	97 mm	81 mm	737 g	530	Y	Jan 2021	US$ 6 499	amazon.com
14.		Sony A7R II	127 mm	96 mm	60 mm	625 g	290	Y	Jun 2015	US$ 3 199	ebay.com
15.		Sony A7R III	127 mm	96 mm	74 mm	650 g	650	Y	Oct 2017	US$ 3 199	ebay.com
16.		Sony A7R IV	129 mm	96 mm	78 mm	665 g	670	Y	Jul 2019	US$ 3 499	ebay.com
17.		Sony A9 III	136 mm	97 mm	83 mm	702 g	530	Y	Nov 2023	US$ 5 999	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

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 OM-3 was launched at a markedly lower price (by 69 percent) than the A1 II, which puts it into a different market segment. 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 imaging sensor is at the core of digital cameras and its size is one of the main determining factors 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 tend to be more expensive and lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the OM System OM-3 features a Four Thirds sensor and the Sony A1 II a full frame sensor. The sensor area in the A1 II is 283 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 OM-3 has a native 4:3 aspect ratio, while the one in the A1 II offers a 3:2 aspect.

With 49.8MP, the A1 II offers a higher resolution than the OM-3 (20.2MP), but the A1 II nevertheless has larger individual pixels (pixel pitch of 4.16μm versus 3.34μm for the OM-3) due to its larger sensor. It is noteworthy in this context that the two cameras were released in close succession, so that their sensors are from the same technological generation. 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.

The resolution advantage of the Sony A1 II implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A1 II for good quality output (200 dots per inch) amounts to 43.2 x 28.8 inches or 109.7 x 73.2 cm, for very good quality (250 dpi) 34.6 x 23 inches or 87.8 x 58.5 cm, and for excellent quality (300 dpi) 28.8 x 19.2 inches or 73.2 x 48.8 cm. The corresponding values for the OM System OM-3 are 25.9 x 19.4 inches or 65.8 x 49.4 cm for good quality, 20.7 x 15.6 inches or 52.7 x 39.5 cm for very good quality, and 17.3 x 13 inches or 43.9 x 32.9 cm for excellent quality prints.

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 OM System OM-3 has a native sensitivity range from ISO 80 to ISO 25600, which can be extended to ISO 80-102400. The corresponding ISO settings for the Sony A1 II are ISO 100 to ISO 32000, with the possibility to increase the ISO range to 50-102400.

Technology-wise, both cameras are equipped with Stacked BSI-CMOS (Stacked Backside Illuminated 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.

Since 2007, DXO Mark has published sensor performance measurements that have been derived using a consistent methodology. 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"). 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.		OM System OM-3	Four Thirds	20.2	5184	3888	4K/60p	23.4	13.7	1852	78
2.		Sony A1 II	Full Frame	49.8	8640	5760	8k/30p	25.4	14.8	3363	97
3.		Olympus E-M1 II	Four Thirds	20.2	5184	3888	4K/30p	23.7	12.8	1312	80
4.		Olympus E-M1 III	Four Thirds	20.2	5184	3888	4K/30p	23.3	13.1	1356	76
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	Four Thirds	20.2	5184	3888	4K/30p	23.4	13.4	1622	78
9.		OM System OM-5 II	Four Thirds	20.2	5184	3888	4K/30p	23.4	13.7	1889	78
10.		Panasonic G9	Four Thirds	20.2	5184	3888	4K/60p	23.1	12.8	1138	74
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.		Sony A1	Full Frame	49.8	8640	5760	8k/30p	25.9	14.5	3163	98
14.		Sony A7R II	Full Frame	42.2	7952	5304	4K/30p	26.0	13.9	3434	98
15.		Sony A7R III	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
16.		Sony A7R IV	Full Frame	60.2	9504	6336	4K/30p	26.0	14.8	3344	99
17.		Sony A9 III	Full Frame	24.0	6000	4000	4K/120p	25.4	14.7	3243	96
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. Both cameras under consideration are equipped with sensors that have a sufficiently high read-out speed for moving images, but the A1 II provides a better video resolution than the OM-3. It can shoot movie footage at 8k/30p, while the OM System is limited to 4K/60p.

Feature comparison

Beyond 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 A1 II offers a substantially higher resolution than the one in the OM-3 (9437k vs 2360k dots). The following table reports on some other key feature differences and similarities of the OM System OM-3, the Sony A1 II, and comparable 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.		OM System OM-3	2360	n	3.0 / 1640	swivel	Y	1/8000s	6.0/s	n	Y
2.		Sony A1 II	9437	n	3.2 / 2100	full-flex	Y	1/8000s	30.0/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-M1 III	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	2360	n	3.0 / 1040	swivel	Y	1/8000s	10.0/s	n	Y
9.		OM System OM-5 II	2360	n	3.0 / 1040	swivel	Y	1/8000s	10.0/s	n	Y
10.		Panasonic G9	3680	Y	3.0 / 1040	swivel	Y	1/8000s	20.0/s	n	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.		Sony A1	9437	n	3.0 / 1440	tilting	Y	1/8000s	30.0/s	n	Y
14.		Sony A7R II	2400	n	3.0 / 1229	tilting	n	1/8000s	5.0/s	n	Y
15.		Sony A7R III	3686	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
16.		Sony A7R IV	5760	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
17.		Sony A9 III	9440	n	3.2 / 2100	full-flex	Y	1/80000s	120.0/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 OM System OM-3 and the Sony A1 II 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.

The OM-3 writes its imaging data to SDXC cards, while the A1 II uses CFexpress (type A) or SDXC cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails. Both cameras support UHS-II cards, which provide for Ultra High Speed data transfer of up to 312 MB/s.

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 OM System OM-3 and Sony A1 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.		OM System OM-3	Y	stereo / mono	Y	Y	micro	3.0	Y	-	Y
2.		Sony A1 II	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
3.		Olympus E-M1 II	Y	stereo / mono	Y	Y	micro	3.0	Y	-	-
4.		Olympus E-M1 III	Y	stereo / mono	Y	Y	micro	3.1	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	Y	stereo / mono	Y	-	micro	2.0	Y	-	Y
9.		OM System OM-5 II	Y	stereo / mono	Y	-	micro	2.0	Y	-	Y
10.		Panasonic G9	Y	stereo / mono	Y	Y	full	3.0	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.		Sony A1	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 III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
16.		Sony A7R IV	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
17.		Sony A9 III	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y

Studio photographers will appreciate that the Sony A1 II (unlike the OM-3) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the OM-3 and the A1 II are recent models that are part of the current product line-up. The A1 II replaced the earlier Sony A1, while the OM-3 does not have a direct predecessor. Further information on the two cameras (e.g. user guides, manuals), as well as related accessories, can be found on the official OM System and Sony websites.

Review summary

So what conclusions can be drawn? Is there a clear favorite between the OM System OM-3 and the Sony A1 II? Which camera is better? Below is a summary of the relative strengths of each of the two contestants.

Reasons to prefer the OM System OM-3:

• Less heavy: Is lighter (by 247g or 33 percent) and hence easier to carry around.
• Longer lasting: Can take more shots (590 versus 520) on a single battery charge.
• More affordable: Was introduced into a lower priced category (69 percent cheaper at launch).

Arguments in favor of the Sony A1 II:

• More detail: Has more megapixels (49.8 vs 20.2MP), which boosts linear resolution by 60%.
• Better image quality: Features bigger pixels on a larger sensor for higher quality imaging.
• Richer colors: The pixel size advantage translates into images with better, more accurate colors.
• More dynamic range: Larger pixels capture a wider spectrum of light and dark details.
• Better low-light sensitivity: Larger pixels means good image quality even under poor lighting.
• Better video: Provides higher definition movie capture (8k/30p vs 4K/60p).
• More detailed viewfinder: Has higher resolution electronic viewfinder (9437k vs 2360k dots).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.9x vs 0.69x).
• Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
• More detailed LCD: Has a higher resolution rear screen (2100k vs 1640k dots).
• Faster burst: Shoots at higher frequency (30 vs 6 flaps/sec) to capture the decisive moment.
• More solid recording: Has a full-sized HDMI port for a sturdy connection to an external recorder.
• Better studio light control: Has a PC Sync socket to connect to professional strobe lights.

If the count of relative strengths (bullet points above) is taken as a measure, the A1 II is the clear winner of the contest (13 : 3 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 wildlife photographer will view the differences between cameras in a way that diverges from the perspective of a family photog, and a person interested in architecture has distinct needs from a sports 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 OM System OM-3 and the Sony A1 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 remains incomplete and does no justice, for example, to the way the OM-3 or the A1 II 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 why hands-on reviews by experts are important. The following table reports the overall ratings of the cameras as published by some of the major 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.		OM System OM-3	..	..	..	86/100	..	..	Feb 2025	US$ 1 999	amazon.com
2.		Sony A1 II	..	..	..	..	..	..	Nov 2024	US$ 6 499	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-M1 III	5/5	..	5/5	83/100	4.5/5	4/5	Feb 2020	US$ 1 799	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	5/5	..	4.5/5	83/100	5/5	4.5/5	Oct 2022	US$ 1 199	amazon.com
9.		OM System OM-5 II	..	..	..	..	..	..	Jun 2025	US$ 1 199	amazon.com
10.		Panasonic G9	..	+ +	5/5	85/100	5/5	5/5	Nov 2017	US$ 1 699	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.		Sony A1	5/5	o	4.5/5	93/100	4.5/5	5/5	Jan 2021	US$ 6 499	amazon.com
14.		Sony A7R II	5/5	+ +	5/5	90/100	5/5	5/5	Jun 2015	US$ 3 199	ebay.com
15.		Sony A7R III	..	+ +	4/5	90/100	4.5/5	5/5	Oct 2017	US$ 3 199	ebay.com
16.		Sony A7R IV	5/5	+	4.5/5	91/100	4.5/5	5/5	Jul 2019	US$ 3 499	ebay.com
17.		Sony A9 III	4.5/5	..	..	91/100	..	..	Nov 2023	US$ 5 999	amazon.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The review scores listed above should be treated 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 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? In case you are interested in seeing how other cameras pair up, just make your choice using the following search menu. As an alternative, you can also directly jump to any one of the listed comparisons that were previously generated by the CAM-parator tool.

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