OM System OM-1 vs Sony A1

The OM System OM-1 and the Sony A1 are two digital cameras that were announced, respectively, in February 2022 and January 2021. Both the OM-1 and the A1 are mirrorless interchangeable lens cameras that are based on a Four Thirds (OM-1) and a full frame (A1) 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-1		Sony A1
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 (5760k dots)		Electronic viewfinder (9437k dots)
3.0" LCD – 1640k dots		3.0" LCD – 1440k dots
Swivel touchscreen		Tilting touchscreen
10 shutter flaps per second		10 shutter flaps per second
In-body stabilization		In-body stabilization
Weathersealed body		Weathersealed body
520 shots per battery charge		530 shots per battery charge
135 x 92 x 73 mm, 599 g		129 x 97 x 81 mm, 737 g

Check OM-1 offers at
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Check A1 price at
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Going beyond this snapshot of core features and characteristics, what are the differences between the OM System OM-1 and the Sony A1? 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 OM System OM-1 and the Sony A1. 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 and the Sony A1 are of equal size. However, the A1 is markedly heavier (23 percent) than the OM-1. 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-1) and the Sony FE Lens Catalog (A1). 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-1 gets 520 shots out of its OM System BLX-1 battery, while the A1 can take 530 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. If you want to switch the focus of the display and review another camera pair, you can move across to the CAM-parator tool and choose from the broad selection of possible camera comparisons 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.		OM System OM-1	135 mm	92 mm	73 mm	599 g	520	Y	Feb 2022	2,199	ebay.com
2.		Sony A1	129 mm	97 mm	81 mm	737 g	530	Y	Jan 2021	6,499	amazon.com
3.		Olympus E-M1 III	134 mm	91 mm	69 mm	580 g	420	Y	Feb 2020	1,799	ebay.com
4.		Olympus E-M1 II	134 mm	91 mm	67 mm	574 g	440	Y	Sep 2016	1,999	ebay.com
5.		OM System OM-1 II	135 mm	92 mm	73 mm	599 g	500	Y	Jan 2024	2,399	amazon.com
6.		OM System OM-5	125 mm	85 mm	50 mm	414 g	310	Y	Oct 2022	1,199	amazon.com
7.		Panasonic G9 II	134 mm	102 mm	90 mm	658 g	390	Y	Sep 2023	1,899	amazon.com
8.		Panasonic GH6	138 mm	100 mm	100 mm	823 g	360	Y	Feb 2022	2,199	amazon.com
9.		Panasonic GH5 II	139 mm	98 mm	87 mm	727 g	400	Y	May 2021	1,699	amazon.com
10.		Panasonic G95	130 mm	94 mm	77 mm	536 g	290	Y	Apr 2019	999	ebay.com
11.		Panasonic G9	137 mm	97 mm	92 mm	658 g	400	Y	Nov 2017	1,699	ebay.com
12.		Panasonic GH5	139 mm	98 mm	87 mm	725 g	410	Y	Jan 2017	1,999	ebay.com
13.		Sony A7R V	131 mm	97 mm	82 mm	723 g	530	Y	Oct 2022	3,899	amazon.com
14.		Sony A7 IV	131 mm	96 mm	80 mm	659 g	580	Y	Oct 2021	2,499	amazon.com
15.		Sony A7R IIIA	127 mm	96 mm	74 mm	650 g	650	Y	Apr 2021	3,199	amazon.com
16.		Sony A7R IVA	129 mm	96 mm	78 mm	665 g	670	Y	Apr 2021	3,499	amazon.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.
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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 OM-1 was launched at a markedly lower price (by 66 percent) than the A1, 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.

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. Moreover, a large sensor camera will give the photographer more control over depth-of-field in the image and, thus, the ability to better isolate a subject from the background. On the downside, larger sensors tend to be associated with larger, more expensive camera bodies and lenses.

Of the two cameras under consideration, the OM System OM-1 features a Four Thirds sensor and the Sony A1 a full frame sensor. The sensor area in the A1 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-1 has a native 4:3 aspect ratio, while the one in the A1 offers a 3:2 aspect.

With 49.8MP, the A1 offers a higher resolution than the OM-1 (20.2MP), but the A1 nevertheless has larger individual pixels (pixel pitch of 4.16μm versus 3.34μm for the OM-1) due to its larger sensor. However, the OM-1 is a somewhat more recent model (by 1 year) than the A1, and its sensor might have benefitted from technological advances during this time that enhance the light gathering capacity of its pixel-units. 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 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A1 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-1 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-1 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 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 assesses and scores the color depth ("DXO Portrait"), dynamic range ("DXO Landscape"), and low-light sensitivity ("DXO Sports") of camera sensors, and also publishes an overall camera score. 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.		OM System OM-1	Four Thirds	20.2	5184	3888	4K/60p	23.4	13.4	1553	77
2.		Sony A1	Full Frame	49.8	8640	5760	8k/30p	25.9	14.5	3163	98
3.		Olympus E-M1 III	Four Thirds	20.2	5184	3888	4K/30p	23.3	13.1	1356	76
4.		Olympus E-M1 II	Four Thirds	20.2	5184	3888	4K/30p	23.7	12.8	1312	80
5.		OM System OM-1 II	Four Thirds	20.2	5184	3888	4K/60p	23.4	13.6	1749	78
6.		OM System OM-5	Four Thirds	20.2	5184	3888	4K/30p	23.4	13.4	1622	78
7.		Panasonic G9 II	Four Thirds	25.0	5776	4336	5.7K/60p	23.4	13.5	1710	78
8.		Panasonic GH6	Four Thirds	25.0	5776	4336	5.7K/60p	23.4	13.4	1555	77
9.		Panasonic GH5 II	Four Thirds	20.2	5184	3888	4K/60p	23.7	13.1	1136	79
10.		Panasonic G95	Four Thirds	20.2	5184	3888	4K/30p	23.2	13.0	1273	75
11.		Panasonic G9	Four Thirds	20.2	5184	3888	4K/60p	23.1	12.8	1138	74
12.		Panasonic GH5	Four Thirds	20.2	5184	3888	4K/60p	23.9	13.0	807	77
13.		Sony A7R V	Full Frame	60.2	9504	6336	8k/24p	26.5	14.8	3187	100
14.		Sony A7 IV	Full Frame	32.7	7008	4672	4K/60p	25.4	14.7	3379	97
15.		Sony A7R IIIA	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
16.		Sony A7R IVA	Full Frame	60.2	9504	6336	4K/30p	26.0	14.8	3344	99
17.		Sony A7S III	Full Frame	12.0	4240	2832	4K/120p	23.7	13.9	2520	86
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 can also record movies. Both cameras under consideration are equipped with sensors that have a sufficiently high read-out speed for moving images, but the A1 provides a better video resolution than the OM-1. It can shoot movie footage at 8k/30p, while the OM System is limited to 4K/60p.

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 A1 offers a substantially higher resolution than the one in the OM-1 (9437k vs 5760k dots). The adjacent table lists some of the other core features of the OM System OM-1 and Sony A1 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.		OM System OM-1	5760	n	3.0 / 1640	swivel	Y	1/8000s	10.0/s	n	Y
2.		Sony A1	9437	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
3.		Olympus E-M1 III	2360	n	3.0 / 1037	swivel	Y	1/8000s	18.0/s	n	Y
4.		Olympus E-M1 II	2360	n	3.0 / 1037	swivel	Y	1/8000s	18.0/s	n	Y
5.		OM System OM-1 II	5760	n	3.0 / 1640	swivel	Y	1/8000s	10.0/s	n	Y
6.		OM System OM-5	2360	n	3.0 / 1040	swivel	Y	1/8000s	10.0/s	n	Y
7.		Panasonic G9 II	3680	n	3.0 / 1840	swivel	Y	1/8000s	10.0/s	n	Y
8.		Panasonic GH6	3680	n	3.0 / 1840	full-flex	Y	1/8000s	14.0/s	n	Y
9.		Panasonic GH5 II	3680	n	3.0 / 1840	swivel	Y	1/8000s	12.0/s	n	Y
10.		Panasonic G95	2360	n	3.0 / 1240	swivel	Y	1/4000s	9.0/s	Y	Y
11.		Panasonic G9	3680	Y	3.0 / 1040	swivel	Y	1/8000s	20.0/s	n	Y
12.		Panasonic GH5	3680	n	3.2 / 1620	swivel	Y	1/8000s	12.0/s	n	Y
13.		Sony A7R V	9440	n	3.2 / 2100	full-flex	Y	1/8000s	10.0/s	n	Y
14.		Sony A7 IV	3686	n	3.0 / 1037	swivel	Y	1/8000s	10.0/s	n	Y
15.		Sony A7R IIIA	3686	n	3.0 / 2340	tilting	Y	1/8000s	10.0/s	n	Y
16.		Sony A7R IVA	5760	n	3.0 / 2340	tilting	Y	1/8000s	10.0/s	n	Y
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, 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-1 and the Sony A1 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-1 writes its imaging data to SDXC cards, while the A1 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-1 and Sony A1 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-1	Y	stereo / mono	Y	Y	micro	3.0	Y	-	Y
2.		Sony A1	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
3.		Olympus E-M1 III	Y	stereo / mono	Y	Y	micro	3.1	Y	-	Y
4.		Olympus E-M1 II	Y	stereo / mono	Y	Y	micro	3.0	Y	-	-
5.		OM System OM-1 II	Y	stereo / mono	Y	Y	micro	3.0	Y	-	Y
6.		OM System OM-5	Y	stereo / mono	Y	-	micro	2.0	Y	-	Y
7.		Panasonic G9 II	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
8.		Panasonic GH6	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
9.		Panasonic GH5 II	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
10.		Panasonic G95	Y	stereo / mono	Y	Y	micro	2.0	Y	-	Y
11.		Panasonic G9	Y	stereo / mono	Y	Y	full	3.0	Y	-	Y
12.		Panasonic GH5	Y	stereo / mono	Y	Y	full	3.1	Y	-	Y
13.		Sony A7R V	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
14.		Sony A7 IV	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
15.		Sony A7R IIIA	Y	stereo / mono	Y	Y	micro	3.2	Y	Y	Y
16.		Sony A7R IVA	Y	stereo / mono	Y	Y	micro	3.2	Y	Y	Y
17.		Sony A7S III	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y

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

The A1 is a recent model that features in the current product line-up of Sony. In contrast, the OM-1 has been discontinued (but can be found pre-owned on ebay). As a replacement in the same line of cameras, the OM-1 was succeeded by the OM System OM-1 II. Further information on the features and operation of the OM-1 and A1 can be found, respectively, in the OM System OM-1 Manual (free pdf) or the online Sony A1 Manual.

Review summary

So what is the bottom line? Which of the two cameras – the OM System OM-1 or the Sony A1 – has the upper hand? Is one clearly better than the other? A synthesis of the relative strong points of each of the models is listed below.

Advantages of the OM System OM-1:

• More detailed LCD: Has a higher resolution rear screen (1640k vs 1440k dots).
• More flexible LCD: Has a swivel screen for odd-angle shots in portrait or landscape orientation.
• More selfie-friendly: Has an articulated screen that can be turned to be front-facing.
• Less heavy: Is lighter (by 138g or 19 percent) and hence easier to carry around.
• More affordable: Was introduced into a lower priced category (66 percent cheaper at launch).
• More modern: Is somewhat more recent (announced 1 year after the A1).

Arguments in favor of the Sony A1:

• 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 5760k dots).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.9x vs 0.82x).
• More solid recording: Has a full-sized HDMI port for a sturdy connection to an external recorder.
• More heavily discounted: Has been on the market for longer (launched in January 2021).

If the count of relative strengths (bullet points above) is taken as a measure, the A1 is the clear winner of the contest (10 : 6 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 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 OM System OM-1 and the Sony A1 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 specs-based evaluation of cameras can be instructive in revealing their potential as photographic tools, it remains incomplete and does no justice, for example, to the way the OM-1 or the A1 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 expert reviews 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.		OM System OM-1	5/5	..	..	87/100	5/5	4.5/5	Feb 2022	2,199	ebay.com
2.		Sony A1	5/5	o	4.5/5	93/100	4.5/5	5/5	Jan 2021	6,499	amazon.com
3.		Olympus E-M1 III	5/5	..	5/5	83/100	4.5/5	4/5	Feb 2020	1,799	ebay.com
4.		Olympus E-M1 II	5/5	+ +	5/5	85/100	4.5/5	4.5/5	Sep 2016	1,999	ebay.com
5.		OM System OM-1 II	..	..	..	..	..	..	Jan 2024	2,399	amazon.com
6.		OM System OM-5	5/5	..	4.5/5	83/100	5/5	4.5/5	Oct 2022	1,199	amazon.com
7.		Panasonic G9 II	5/5	..	4.5/5	87/100	..	4.5/5	Sep 2023	1,899	amazon.com
8.		Panasonic GH6	5/5	+ +	5/5	87/100	5/5	5/5	Feb 2022	2,199	amazon.com
9.		Panasonic GH5 II	4.5/5	..	4.5/5	85/100	4.5/5	5/5	May 2021	1,699	amazon.com
10.		Panasonic G95	4.5/5	+	4.5/5	83/100	4.5/5	4.5/5	Apr 2019	999	ebay.com
11.		Panasonic G9	..	+ +	5/5	85/100	5/5	5/5	Nov 2017	1,699	ebay.com
12.		Panasonic GH5	4.5/5	+ +	..	85/100	4.5/5	5/5	Jan 2017	1,999	ebay.com
13.		Sony A7R V	5/5	+ +	4.5/5	92/100	..	..	Oct 2022	3,899	amazon.com
14.		Sony A7 IV	5/5	+ +	4.5/5	89/100	4.5/5	4.5/5	Oct 2021	2,499	amazon.com
15.		Sony A7R IIIA	..	+ +	4/5	90/100	4.5/5	5/5	Apr 2021	3,199	amazon.com
16.		Sony A7R IVA	5/5	+	4.5/5	91/100	4.5/5	5/5	Apr 2021	3,499	amazon.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.

Care should be taken when interpreting the review scores above, though. The ratings are only valid when referring to cameras in the same category and of the same age. 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. Also, please note that some of the review sites have changed their methodology and reporting over time.

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Other camera comparisons

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