OM System OM-1 vs Sony A7 IV

The OM System OM-1 and the Sony Alpha A7 IV are two enthusiast cameras that were announced, respectively, in February 2022 and October 2021. Both the OM-1 and the A7 IV are mirrorless interchangeable lens cameras that are based on a Four Thirds (OM-1) and a full frame (A7 IV) sensor. The OM System has a resolution of 20.2 megapixels, whereas the Sony provides 32.7 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 A7 IV
Mirrorless system camera		Mirrorless system camera
Micro Four Thirds lenses		Sony E mount lenses
20.2 MP – Four Thirds sensor		32.7 MP – Full Frame sensor
4K/60p Video		4K/60p Video
ISO 80-25,600 (80 - 102,400)		ISO 100-51,200 (50 - 204,800)
Electronic viewfinder (5760k dots)		Electronic viewfinder (3686k dots)
3.0" LCD – 1640k dots		3.0" LCD – 1037k dots
Swivel touchscreen		Swivel 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		580 shots per battery charge
135 x 92 x 73 mm, 599 g		131 x 96 x 80 mm, 659 g

Check OM-1 offers at
ebay.com
Check A7 IV price at
amazon.com

Going beyond this snapshot of core features and characteristics, what are the differences between the OM System OM-1 and the Sony Alpha A7 IV? 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-1 and the Sony A7 IV 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 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 Sony A7 IV is somewhat larger (1 percent) than the OM System OM-1. Moreover, the A7 IV is markedly heavier (10 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 (A7 IV). 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 A7 IV can take 580 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 (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 A7 IV	131 mm	96 mm	80 mm	659 g	580	Y	Oct 2021	2,499	amazon.com
3.		Olympus E-M1 II	134 mm	91 mm	67 mm	574 g	440	Y	Sep 2016	1,999	ebay.com
4.		Olympus E-M1 III	134 mm	91 mm	69 mm	580 g	420	Y	Feb 2020	1,799	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	137 mm	97 mm	92 mm	658 g	400	Y	Nov 2017	1,699	ebay.com
8.		Panasonic G9 II	134 mm	102 mm	90 mm	658 g	390	Y	Sep 2023	1,899	amazon.com
9.		Panasonic G95	130 mm	94 mm	77 mm	536 g	290	Y	Apr 2019	999	ebay.com
10.		Panasonic GH5	139 mm	98 mm	87 mm	725 g	410	Y	Jan 2017	1,999	ebay.com
11.		Panasonic GH5 II	139 mm	98 mm	87 mm	727 g	400	Y	May 2021	1,699	amazon.com
12.		Panasonic GH6	138 mm	100 mm	100 mm	823 g	360	Y	Feb 2022	2,199	amazon.com
13.		Sony A1	129 mm	97 mm	81 mm	737 g	530	Y	Jan 2021	6,499	amazon.com
14.		Sony A7 III	127 mm	96 mm	74 mm	650 g	610	Y	Feb 2018	1,999	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 V	131 mm	97 mm	82 mm	723 g	530	Y	Oct 2022	3,899	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.
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-1 was launched at a somewhat lower price (by 12 percent) than the A7 IV, 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 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. 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-1 features a Four Thirds sensor and the Sony A7 IV a full frame sensor. The sensor area in the A7 IV is 281 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 A7 IV offers a 3:2 aspect.

With 32.7MP, the A7 IV offers a higher resolution than the OM-1 (20.2MP), but the A7 IV nevertheless has larger individual pixels (pixel pitch of 5.12μm versus 3.34μm for the OM-1) due to its larger sensor. However, the OM-1 is a somewhat more recent model (by 3 months) than the A7 IV, 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 A7 IV implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A7 IV for good quality output (200 dots per inch) amounts to 35 x 23.4 inches or 89 x 59.3 cm, for very good quality (250 dpi) 28 x 18.7 inches or 71.2 x 47.5 cm, and for excellent quality (300 dpi) 23.4 x 15.6 inches or 59.3 x 39.6 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.

Unlike the A7 IV, the OM-1 has the capacity to capture high quality composite images (80MP) by combining multiple shots after shifting its 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 Alpha A7 IV are ISO 100 to ISO 51200, with the possibility to increase the ISO range to 50-204800.

In terms of underlying technology, the OM-1 is build around a Stacked BSI-CMOS sensor, while the A7 IV uses a 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 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-1	Four Thirds	20.2	5184	3888	4K/60p	23.4	13.4	1553	77
2.		Sony A7 IV	Full Frame	32.7	7008	4672	4K/60p	25.4	14.7	3379	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.		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	Four Thirds	20.2	5184	3888	4K/60p	23.1	12.8	1138	74
8.		Panasonic G9 II	Four Thirds	25.0	5776	4336	5.7K/60p	23.4	13.5	1710	78
9.		Panasonic G95	Four Thirds	20.2	5184	3888	4K/30p	23.2	13.0	1273	75
10.		Panasonic GH5	Four Thirds	20.2	5184	3888	4K/60p	23.9	13.0	807	77
11.		Panasonic GH5 II	Four Thirds	20.2	5184	3888	4K/60p	23.7	13.1	1136	79
12.		Panasonic GH6	Four Thirds	25.0	5776	4336	5.7K/60p	23.4	13.4	1555	77
13.		Sony A1	Full Frame	49.8	8640	5760	8k/30p	25.9	14.5	3163	98
14.		Sony A7 III	Full Frame	24.0	6000	4000	4K/30p	25.0	14.7	3730	96
15.		Sony A7R IIIA	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
16.		Sony A7R V	Full Frame	60.2	9504	6336	8k/24p	26.5	14.8	3187	100
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 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, and both provide the same movie specifications (4K/60p).

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. The two cameras under consideration 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 A7 IV (5760k vs 3686k dots). The following table reports on some other key feature differences and similarities of the OM System OM-1, the Sony A7 IV, 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-1	5760	n	3.0 / 1640	swivel	Y	1/8000s	10.0/s	n	Y
2.		Sony A7 IV	3686	n	3.0 / 1037	swivel	Y	1/8000s	10.0/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.		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	3680	Y	3.0 / 1040	swivel	Y	1/8000s	20.0/s	n	Y
8.		Panasonic G9 II	3680	n	3.0 / 1840	swivel	Y	1/8000s	10.0/s	n	Y
9.		Panasonic G95	2360	n	3.0 / 1240	swivel	Y	1/4000s	9.0/s	Y	Y
10.		Panasonic GH5	3680	n	3.2 / 1620	swivel	Y	1/8000s	12.0/s	n	Y
11.		Panasonic GH5 II	3680	n	3.0 / 1840	swivel	Y	1/8000s	12.0/s	n	Y
12.		Panasonic GH6	3680	n	3.0 / 1840	full-flex	Y	1/8000s	14.0/s	n	Y
13.		Sony A1	9437	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
14.		Sony A7 III	2359	n	3.0 / 922	tilting	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 V	9440	n	3.2 / 2100	full-flex	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 has 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 A7 IV uses CFexpress (type A) or SDXC cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails. Moreover, both the OM-1 and the A7 IV support UHS-II cards, which provide for Ultra High Speed data transfer of up to 312 MB/s, on both slots.

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 Alpha A7 IV 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 A7 IV	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.		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	Y	stereo / mono	Y	Y	full	3.0	Y	-	Y
8.		Panasonic G9 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 GH5	Y	stereo / mono	Y	Y	full	3.1	Y	-	Y
11.		Panasonic GH5 II	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
12.		Panasonic GH6	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
13.		Sony A1	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
14.		Sony A7 III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
15.		Sony A7R IIIA	Y	stereo / mono	Y	Y	micro	3.2	Y	Y	Y
16.		Sony A7R V	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
17.		Sony A7S III	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y

Studio photographers will appreciate that the OM System OM-1 (unlike the A7 IV) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

The A7 IV 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 A7 IV can be found, respectively, in the OM System OM-1 Manual (free pdf) or the online Sony A7 IV Manual.

Review summary

So what conclusions can be drawn? Is there a clear favorite between the OM System OM-1 and the Sony A7 IV? 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-1:

• High quality composites: Can combine several shots after pixel-shifting its sensor.
• More detailed viewfinder: Has higher resolution electronic viewfinder (5760k vs 3686k dots).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.82x vs 0.78x).
• More detailed LCD: Has a higher resolution rear screen (1640k vs 1037k dots).
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• Better studio light control: Has a PC Sync socket to connect to professional strobe lights.
• More affordable: Was introduced into a lower priced segment (12 percent cheaper at launch).
• More modern: Is somewhat more recent (announced 3 months after the A7 IV).

Arguments in favor of the Sony Alpha A7 IV:

• More detail: Has more megapixels (32.7 vs 20.2MP), which boosts linear resolution by 30%.
• 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.
• Longer lasting: Gets more shots (580 versus 520) out of a single battery charge.
• 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 October 2021).

If the count of relative strengths (bullet points above) is taken as a measure, the match-up finishes in a tie (8 points each). 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-1 and the Sony A7 IV 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-1 or the A7 IV 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 (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 A7 IV	5/5	+ +	4.5/5	89/100	4.5/5	4.5/5	Oct 2021	2,499	amazon.com
3.		Olympus E-M1 II	5/5	+ +	5/5	85/100	4.5/5	4.5/5	Sep 2016	1,999	ebay.com
4.		Olympus E-M1 III	5/5	..	5/5	83/100	4.5/5	4/5	Feb 2020	1,799	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	..	+ +	5/5	85/100	5/5	5/5	Nov 2017	1,699	ebay.com
8.		Panasonic G9 II	5/5	..	4.5/5	87/100	..	4.5/5	Sep 2023	1,899	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 GH5	4.5/5	+ +	..	85/100	4.5/5	5/5	Jan 2017	1,999	ebay.com
11.		Panasonic GH5 II	4.5/5	..	4.5/5	85/100	4.5/5	5/5	May 2021	1,699	amazon.com
12.		Panasonic GH6	5/5	+ +	5/5	87/100	5/5	5/5	Feb 2022	2,199	amazon.com
13.		Sony A1	5/5	o	4.5/5	93/100	4.5/5	5/5	Jan 2021	6,499	amazon.com
14.		Sony A7 III	..	+ +	4.5/5	89/100	5/5	5/5	Feb 2018	1,999	amazon.com
15.		Sony A7R IIIA	..	+ +	4/5	90/100	4.5/5	5/5	Apr 2021	3,199	amazon.com
16.		Sony A7R V	5/5	+ +	4.5/5	92/100	..	..	Oct 2022	3,899	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.

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. 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. 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

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