Leica SL2-S vs Sony A9 III

The Leica SL2-S and the Sony Alpha A9 III are two digital cameras that were revealed to the public, respectively, in December 2020 and November 2023. Both the Leica SL2-S and the A9 III are mirrorless interchangeable lens cameras that are equipped with a full frame sensor. Both cameras offer a resolution of 24 megapixels.

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

Headline Specifications

Leica SL2-S		Sony A9 III
Mirrorless system camera		Mirrorless system camera
Leica L mount lenses		Sony E mount lenses
24 MP – Full Frame sensor		24 MP – Full Frame sensor
4K/60p Video		4K/120p Video
ISO 100-50,000 (50 - 100,000)		ISO 250-25,600 (125 - 51,200)
Electronic viewfinder (5760k dots)		Electronic viewfinder (9440k dots)
3.2" LCD – 2100k dots		3.2" LCD – 2100k dots
Fixed touchscreen		Fully flexible touchscreen
20 shutter flaps per second		120 shutter flaps per second
In-body stabilization		In-body stabilization
Weathersealed body		Weathersealed body
510 shots per battery charge		530 shots per battery charge
146 x 107 x 83 mm, 931 g		136 x 97 x 83 mm, 702 g

Check Leica SL2-S price at
amazon.com
Check A9 III price at
amazon.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Leica SL2-S and the Sony Alpha A9 III? 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 Leica SL2-S and the Sony A9 III is provided 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.

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Sony A9 III is notably smaller (16 percent) than the Leica SL2-S. Moreover, the A9 III is markedly lighter (25 percent) than the Leica SL2-S. 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. Hence, you might want to study and compare the specifications of available lenses in order to get the full picture of the size and weight of the two camera systems.

Concerning battery life, the Leica SL2-S gets 510 shots out of its Leica BP-SCL4 battery, while the A9 III 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 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	Street Price
1.		Leica SL2-S	146 mm	107 mm	83 mm	931 g	510	Y	Dec 2020	US$ 4 899	amazon.com
2.		Sony A9 III	136 mm	97 mm	83 mm	702 g	530	Y	Nov 2023	US$ 5 999	amazon.com
3.		Canon R3	150 mm	143 mm	87 mm	1015 g	760	Y	Sep 2021	US$ 5 999	amazon.com
4.		Leica SL	147 mm	104 mm	39 mm	847 g	400	Y	Oct 2015	US$ 7 449	ebay.com
5.		Leica SL2	146 mm	107 mm	42 mm	953 g	370	Y	Nov 2019	US$ 5 999	amazon.com
6.		Nikon Z6 II	134 mm	101 mm	70 mm	705 g	410	Y	Oct 2020	US$ 1 999	amazon.com
7.		Olympus E-M1X	144 mm	147 mm	75 mm	997 g	870	Y	Jan 2019	US$ 2 999	ebay.com
8.		Panasonic S1	149 mm	110 mm	97 mm	1017 g	400	Y	Feb 2019	US$ 2 499	amazon.com
9.		Panasonic S1H	151 mm	114 mm	110 mm	1052 g	400	Y	May 2019	US$ 3 999	amazon.com
10.		Panasonic S1R	149 mm	110 mm	97 mm	1016 g	380	Y	Feb 2019	US$ 3 699	amazon.com
11.		Panasonic S5	133 mm	98 mm	82 mm	714 g	440	Y	Sep 2020	US$ 1 999	amazon.com
12.		Sony A1	129 mm	97 mm	81 mm	737 g	530	Y	Jan 2021	US$ 6 499	amazon.com
13.		Sony A7 II	127 mm	96 mm	60 mm	599 g	350	Y	Nov 2014	US$ 1 999	ebay.com
14.		Sony A7 III	127 mm	96 mm	74 mm	650 g	610	Y	Feb 2018	US$ 1 999	amazon.com
15.		Sony A9	127 mm	96 mm	63 mm	673 g	650	Y	Apr 2017	US$ 4 499	ebay.com
16.		Sony A9 II	129 mm	96 mm	76 mm	678 g	690	Y	Oct 2019	US$ 4 499	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

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 Leica SL2-S was launched at a somewhat lower price (by 18 percent) than the A9 III, 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. 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 tend to be more expensive and lead to bigger and heavier cameras and lenses.

Both cameras under consideration feature a full frame sensor, but their sensors differ slightly in size. The sensor area in the A9 III is 2 percent smaller. They nevertheless have the same format factor of 1.0. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

Even though the Leica SL2-S has a slightly larger sensor, both cameras offer the same resolution of 24 megapixels. This implies that the Leica SL2-S has a lower pixel density and larger individual pixels (with a pixel pitch of 6.00μm versus 5.94μm for the A9 III), which gives it a potential advantage in terms of light gathering capacity. It should, however, be noted that the A9 III is much more recent (by 2 years and 10 months) than the Leica SL2-S, and its sensor will have benefitted from technological advances during this time that at least partly compensate for the smaller pixel size. Coming back to sensor resolution, it should be mentioned that the Leica SL2-S has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

The A9 III has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

Unlike the A9 III, the Leica SL2-S has the capacity to capture high quality composite images (96MP) 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 Leica SL2-S has a native sensitivity range from ISO 100 to ISO 50000, which can be extended to ISO 50-100000. The corresponding ISO settings for the Sony Alpha A9 III are ISO 250 to ISO 25600, with the possibility to increase the ISO range to 125-51200.

In terms of underlying technology, the Leica SL2-S is build around a CMOS sensor, while the A9 III uses a Stacked 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.		Leica SL2-S	Full Frame	24.0	6000	4000	4K/60p	25.2	14.1	3504	95
2.		Sony A9 III	Full Frame	24.0	6000	4000	4K/120p	25.4	14.7	3243	96
3.		Canon R3	Full Frame	24.0	6000	4000	6K/60p	25.0	14.7	4086	96
4.		Leica SL	Full Frame	24.0	6000	4000	4K/30p	25.0	13.4	1821	88
5.		Leica SL2	Full Frame	46.7	8368	5584	4K/60p	25.3	14.3	2866	95
6.		Nikon Z6 II	Full Frame	24.3	6048	4024	4K/60p	25.0	14.4	3303	94
7.		Olympus E-M1X	Four Thirds	20.2	5184	3888	4K/30p	23.2	13.0	1254	75
8.		Panasonic S1	Full Frame	24.0	6000	4000	4K/60p	25.2	14.5	3333	95
9.		Panasonic S1H	Full Frame	24.0	6000	4000	6K/30p	25.2	14.2	2805	94
10.		Panasonic S1R	Full Frame	46.7	8368	5584	4K/60p	26.4	14.1	3525	100
11.		Panasonic S5	Full Frame	24.0	6000	4000	4K/60p	25.1	14.5	2697	94
12.		Sony A1	Full Frame	49.8	8640	5760	8k/30p	25.9	14.5	3163	98
13.		Sony A7 II	Full Frame	24.0	6000	4000	1080/60p	24.9	13.6	2449	90
14.		Sony A7 III	Full Frame	24.0	6000	4000	4K/30p	25.0	14.7	3730	96
15.		Sony A9	Full Frame	24.0	6000	4000	4K/30p	24.9	13.3	3517	92
16.		Sony A9 II	Full Frame	24.0	6000	4000	4K/30p	25.0	14.0	3434	93
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 A9 III provides a faster frame rate than the Leica SL2-S. It can shoot movie footage at 4K/120p, while the Leica 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 A9 III offers a substantially higher resolution than the one in the Leica SL2-S (9440k vs 5760k dots). The following table reports on some other key feature differences and similarities of the Leica SL2-S, the Sony A9 III, 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.		Leica SL2-S	5760	Y	3.2 / 2100	fixed	Y	1/8000s	20.0/s	n	Y
2.		Sony A9 III	9440	n	3.2 / 2100	full-flex	Y	1/80000s	120.0/s	n	Y
3.		Canon R3	5760	Y	3.2 / 4150	swivel	Y	1/8000s	12.0/s	n	Y
4.		Leica SL	4400	Y	3.0 / 1040	fixed	Y	1/8000s	11.0/s	n	n
5.		Leica SL2	5760	Y	3.2 / 2100	fixed	Y	1/8000s	10.0/s	n	Y
6.		Nikon Z6 II	3690	Y	3.2 / 2100	tilting	Y	1/8000s	14.0/s	n	Y
7.		Olympus E-M1X	2360	n	3.0 / 1037	swivel	Y	1/8000s	18.0/s	n	Y
8.		Panasonic S1	5760	Y	3.2 / 2100	full-flex	Y	1/8000s	9.0/s	n	Y
9.		Panasonic S1H	5760	Y	3.2 / 2330	swivel	Y	1/8000s	9.0/s	n	Y
10.		Panasonic S1R	5760	Y	3.2 / 2100	full-flex	Y	1/8000s	9.0/s	n	Y
11.		Panasonic S5	2360	n	3.0 / 1840	swivel	Y	1/8000s	7.0/s	n	Y
12.		Sony A1	9437	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
13.		Sony A7 II	2400	n	3.0 / 1230	tilting	n	1/8000s	5.0/s	n	Y
14.		Sony A7 III	2359	n	3.0 / 922	tilting	Y	1/8000s	10.0/s	n	Y
15.		Sony A9	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
16.		Sony A9 II	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that is present on the Leica SL2-S, but is missing on the A9 III is a top-level LCD. While being, of course, smaller than the rear screen, the control panel conveys some of the essential shooting information and can be convenient for quick and easy settings verification.

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 Leica SL2-S and the Sony A9 III 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 Leica SL2-S writes its imaging data to SDXC cards, while the A9 III 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 Leica SL2-S and Sony Alpha A9 III 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.		Leica SL2-S	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
2.		Sony A9 III	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
3.		Canon R3	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
4.		Leica SL	Y	stereo / mono	Y	Y	full	3.0	Y	-	-
5.		Leica SL2	Y	stereo / mono	Y	Y	full	3.1	Y	-	Y
6.		Nikon Z6 II	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
7.		Olympus E-M1X	Y	stereo / mono	Y	Y	micro	3.0	Y	-	Y
8.		Panasonic S1	Y	stereo / mono	Y	Y	full	3.1	Y	-	Y
9.		Panasonic S1H	Y	stereo / mono	Y	Y	full	3.1	Y	-	Y
10.		Panasonic S1R	Y	stereo / mono	Y	Y	full	3.1	Y	-	Y
11.		Panasonic S5	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
12.		Sony A1	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
13.		Sony A7 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
14.		Sony A7 III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
15.		Sony A9	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	Y
16.		Sony A9 II	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y

Studio photographers will appreciate that the Sony A9 III (unlike the Leica SL2-S) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the Leica SL2-S and the A9 III are recent models that are part of the current product line-up. The A9 III replaced the earlier Sony A9 II, while the Leica SL2-S does not have a direct predecessor. Further information on the features and operation of the Leica SL2-S and A9 III can be found, respectively, in the Leica SL2-S Manual (free pdf) or the online Sony A9 III Manual.

Review summary

So how do things add up? Which of the two cameras – the Leica SL2-S or the Sony A9 III – has the upper hand? Is one clearly better than the other? Below is a summary of the relative strengths of each of the two contestants.

Arguments in favor of the Leica SL2-S:

• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• High quality composites: Can combine several shots after pixel-shifting its sensor.
• Easier setting verification: Features an LCD display on top to control shooting parameters.
• More prestigious: Has the Leica luxury appeal, which ensures a high resale price.
• 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 December 2020).

Reasons to prefer the Sony Alpha A9 III:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Better video: Provides higher movie framerates (4K/120p versus 4K/60p).
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• More detailed viewfinder: Has higher resolution electronic viewfinder (9440k vs 5760k dots).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.9x vs 0.78x).
• More flexible LCD: Has a full-flex 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.
• Faster shutter: Has higher mechanical shutter speed (1/80000s vs 1/8000s) to freeze action.
• Faster burst: Shoots at higher frequency (120 vs 20 flaps/sec) to capture the decisive moment.
• More compact: Is smaller (136x97mm vs 146x107mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 229g or 25 percent) and is thus easier to take along.
• Better studio light control: Has a PC Sync socket to connect to professional strobe lights.
• More modern: Reflects 2 years and 10 months of technical progress since the Leica SL2-S launch.

If the number of relative strengths (bullet points above) is taken as a guide, the A9 III is the clear winner of the contest (13 : 6 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 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 Leica SL2-S and the Sony A9 III 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 Leica SL2-S and the A9 III in practical situations. 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 where reviews by experts come in. 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	Street Price
1.		Leica SL2-S	4/5	..	4/5	..	4.5/5	4.5/5	Dec 2020	US$ 4 899	amazon.com
2.		Sony A9 III	4.5/5	..	..	..	..	..	Nov 2023	US$ 5 999	amazon.com
3.		Canon R3	5/5	o	4.5/5	..	5/5	4.5/5	Sep 2021	US$ 5 999	amazon.com
4.		Leica SL	4/5	..	4/5	84/100	4.5/5	4/5	Oct 2015	US$ 7 449	ebay.com
5.		Leica SL2	4/5	..	4.5/5	..	4.5/5	4/5	Nov 2019	US$ 5 999	amazon.com
6.		Nikon Z6 II	4.5/5	..	4/5	89/100	4.5/5	4.5/5	Oct 2020	US$ 1 999	amazon.com
7.		Olympus E-M1X	4.5/5	o	5/5	85/100	4.5/5	..	Jan 2019	US$ 2 999	ebay.com
8.		Panasonic S1	4.5/5	+ +	4.5/5	88/100	4.5/5	4/5	Feb 2019	US$ 2 499	amazon.com
9.		Panasonic S1H	..	..	4/5	90/100	..	..	May 2019	US$ 3 999	amazon.com
10.		Panasonic S1R	4.5/5	..	4.6/5	89/100	4.5/5	4.5/5	Feb 2019	US$ 3 699	amazon.com
11.		Panasonic S5	4.5/5	+ +	4.5/5	88/100	4.5/5	4.5/5	Sep 2020	US$ 1 999	amazon.com
12.		Sony A1	5/5	o	4.5/5	93/100	4.5/5	5/5	Jan 2021	US$ 6 499	amazon.com
13.		Sony A7 II	5/5	+	4/5	82/100	4.5/5	5/5	Nov 2014	US$ 1 999	ebay.com
14.		Sony A7 III	..	+ +	4.5/5	89/100	5/5	5/5	Feb 2018	US$ 1 999	amazon.com
15.		Sony A9	5/5	+ +	4.8/5	89/100	5/5	5/5	Apr 2017	US$ 4 499	ebay.com
16.		Sony A9 II	..	..	5/5	90/100	5/5	5/5	Oct 2019	US$ 4 499	amazon.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The above review scores should be interpreted 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. 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.

Check Leica SL2-S price at
amazon.com
Check A9 III price at
amazon.com

Other camera comparisons

Did this review help to inform your camera decision process? In case you would like to check on the differences and similarities of other camera models, just make your choice using the following search menu. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored.

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Check Leica SL2-S price at
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Check A9 III price at
amazon.com

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