Sony A9 vs A7S II

The Sony Alpha A9 and the Sony Alpha 7S II are two professional cameras that were announced, respectively, in April 2017 and September 2015. Both the A9 and the A7S II are mirrorless interchangeable lens cameras that are equipped with a full frame sensor. The A9 has a resolution of 24 megapixels, whereas the A7S II provides 12 MP.

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

Headline Specifications

Sony A9		Sony A7S II
Mirrorless system camera		Mirrorless system camera
Sony E mount lenses		Sony E mount lenses
24 MP – Full Frame sensor		12 MP – Full Frame sensor
4K/30p Video		4K/30p Video
ISO 100-51,200 (50 - 204,800)		ISO 100-102,400 (50 - 409,600)
Electronic viewfinder (3686k dots)		Electronic viewfinder (2400k dots)
3.0" LCD – 1440k dots		3.0" LCD – 1229k dots
Tilting touchscreen		Tilting screen (no touchscreen)
20 shutter flaps per second		5 shutter flaps per second
In-body stabilization		In-body stabilization
Weathersealed body		Weathersealed body
650 shots per battery charge		370 shots per battery charge
127 x 96 x 63 mm, 673 g		127 x 96 x 60 mm, 627 g

Check A9 offers at
ebay.com
Check A7S II offers at
ebay.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Sony Alpha A9 and the Sony Alpha 7S 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 Sony A9 and the Sony A7S 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 size dimensions are rounded to the nearest millimeter.

In this particular case, the Sony A9 and the Sony A7S II have exactly the same width and height, and, thus, have identically-sized bodies. However, the A7S II is markedly lighter (7 percent) than the A9. 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 Sony FE 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 A9 gets 650 shots out of its Sony NP-FZ100 battery, while the A7S II can take 370 images on a single charge of its Sony NP-FW50 power pack. The battery packs of both cameras can be charged via USB, which can be very convenient when travelling.

The table below summarizes the key physical specs of the two cameras alongside a broader set of comparators. 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.		Sony A9	127 mm	96 mm	63 mm	673 g	650	Y	Apr 2017	4,499	ebay.com
2.		Sony A7S II	127 mm	96 mm	60 mm	627 g	370	Y	Sep 2015	2,999	ebay.com
3.		Nikon Z6	134 mm	101 mm	67 mm	675 g	310	Y	Aug 2018	1,999	ebay.com
4.		Sony A7 II	127 mm	96 mm	60 mm	599 g	350	Y	Nov 2014	1,999	ebay.com
5.		Sony A7 III	127 mm	96 mm	74 mm	650 g	610	Y	Feb 2018	1,999	amazon.com
6.		Sony A7 IV	131 mm	96 mm	80 mm	659 g	580	Y	Oct 2021	2,499	amazon.com
7.		Sony A7R II	127 mm	96 mm	60 mm	625 g	290	Y	Jun 2015	3,199	ebay.com
8.		Sony A7R III	127 mm	96 mm	74 mm	650 g	650	Y	Oct 2017	3,199	ebay.com
9.		Sony A7R IIIA	127 mm	96 mm	74 mm	650 g	650	Y	Apr 2021	3,199	amazon.com
10.		Sony A7R IV	129 mm	96 mm	78 mm	665 g	670	Y	Jul 2019	3,499	ebay.com
11.		Sony A7R V	131 mm	97 mm	82 mm	723 g	530	Y	Oct 2022	3,899	amazon.com
12.		Sony A7S	127 mm	94 mm	48 mm	489 g	380	Y	Apr 2014	2,499	ebay.com
13.		Sony A7S III	127 mm	97 mm	81 mm	699 g	600	Y	Jul 2020	3,499	amazon.com
14.		Sony A9 II	129 mm	96 mm	76 mm	678 g	690	Y	Oct 2019	4,499	amazon.com
15.		Sony A99	147 mm	111 mm	78 mm	812 g	500	Y	Sep 2012	2,799	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 retail prices at the time of the camera’s release place the model in the market relative to other models in the producer’s line-up and the competition. The A7S II was launched at a markedly lower price (by 33 percent) than the A9, which puts it into a different market segment. Normally, street prices remain initially close to the MSRP, but after a couple of months, the first discounts appear. 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. 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 associated with larger, more expensive camera bodies and lenses.

Both cameras under consideration feature a full frame sensor and have a format factor (sometimes also referred to as "crop factor") of 1.0. Within the spectrum of camera sensors, this places the review cameras among the large-sensor cameras that aim for top notch image quality. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

While the two cameras under review share the same sensor size, the A9 offers a higher resolution of 24 megapixels, compared with 12 MP of the A7S II. This megapixels advantage translates into a 42 percent gain in linear resolution. On the other hand, these sensor specs imply that the A9 has a higher pixel density and a smaller size of the individual pixel (with a pixel pitch of 5.94μm versus 8.40μm for the A7S II). In this context, it should be noted, however, that the A9 is a somewhat more recent model (by 1 year and 7 months) than the A7S II, and its sensor might have benefitted from technological advances during this time that at least partly compensate for the smaller pixel size.

The resolution advantage of the Sony A9 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A9 for good quality output (200 dots per inch) amounts to 30 x 20 inches or 76.2 x 50.8 cm, for very good quality (250 dpi) 24 x 16 inches or 61 x 40.6 cm, and for excellent quality (300 dpi) 20 x 13.3 inches or 50.8 x 33.9 cm. The corresponding values for the Sony A7S II are 21.2 x 14.2 inches or 53.8 x 36 cm for good quality, 17 x 11.3 inches or 43.1 x 28.8 cm for very good quality, and 14.1 x 9.4 inches or 35.9 x 24 cm for excellent quality prints.

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

The Sony Alpha A9 has a native sensitivity range from ISO 100 to ISO 51200, which can be extended to ISO 50-204800. The corresponding ISO settings for the Sony Alpha 7S II are ISO 100 to ISO 102400, with the possibility to increase the ISO range to 50-409600.

In terms of underlying technology, the A9 is build around a Stacked BSI-CMOS sensor, while the A7S II uses a 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 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. Of the two cameras under review, the A9 has a notably higher overall DXO score than the A7S II (overall score 7 points higher), which gives it an advantage in terms of imaging quality. This advantage is based on 1.3 bits higher color depth, and 0.2 stops in additional low light sensitivity. 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.		Sony A9	Full Frame	24.0	6000	4000	4K/30p	24.9	13.3	3517	92
2.		Sony A7S II	Full Frame	12.0	4240	2832	4K/30p	23.6	13.3	2993	85
3.		Nikon Z6	Full Frame	24.3	6048	4024	4K/30p	25.3	14.3	3299	95
4.		Sony A7 II	Full Frame	24.0	6000	4000	1080/60p	24.9	13.6	2449	90
5.		Sony A7 III	Full Frame	24.0	6000	4000	4K/30p	25.0	14.7	3730	96
6.		Sony A7 IV	Full Frame	32.7	7008	4672	4K/60p	25.4	14.7	3379	97
7.		Sony A7R II	Full Frame	42.2	7952	5304	4K/30p	26.0	13.9	3434	98
8.		Sony A7R III	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
9.		Sony A7R IIIA	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
10.		Sony A7R IV	Full Frame	60.2	9504	6336	4K/30p	26.0	14.8	3344	99
11.		Sony A7R V	Full Frame	60.2	9504	6336	8k/24p	26.5	14.8	3187	100
12.		Sony A7S	Full Frame	12.0	4240	2832	1080/60p	23.9	13.2	3702	87
13.		Sony A7S III	Full Frame	12.0	4240	2832	4K/120p	23.7	13.9	2520	86
14.		Sony A9 II	Full Frame	24.0	6000	4000	4K/30p	25.0	14.0	3434	93
15.		Sony A99	Full Frame	24.0	6000	4000	1080/60p	25.0	14.0	1555	89

Many modern cameras cannot only take still pictures, but also record videos. Both cameras under consideration have a sensor with sufficiently fast read-out times for moving pictures, and both provide the same movie specifications (4K/30p).

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. The two cameras under consideration are similar with respect to both having an electronic viewfinder. However, the one in the A9 offers a substantially higher resolution than the one in the A7S II (3686k vs 2400k dots). The adjacent table lists some of the other core features of the Sony A9 and Sony A7S II 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.		Sony A9	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
2.		Sony A7S II	2400	n	3.0 / 1229	tilting	n	1/8000s	5.0/s	n	Y
3.		Nikon Z6	3690	Y	3.2 / 2100	tilting	Y	1/8000s	12.0/s	n	Y
4.		Sony A7 II	2400	n	3.0 / 1230	tilting	n	1/8000s	5.0/s	n	Y
5.		Sony A7 III	2359	n	3.0 / 922	tilting	Y	1/8000s	10.0/s	n	Y
6.		Sony A7 IV	3686	n	3.0 / 1037	swivel	Y	1/8000s	10.0/s	n	Y
7.		Sony A7R II	2400	n	3.0 / 1229	tilting	n	1/8000s	5.0/s	n	Y
8.		Sony A7R III	3686	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
9.		Sony A7R IIIA	3686	n	3.0 / 2340	tilting	Y	1/8000s	10.0/s	n	Y
10.		Sony A7R IV	5760	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
11.		Sony A7R V	9440	n	3.2 / 2100	full-flex	Y	1/8000s	10.0/s	n	Y
12.		Sony A7S	2400	n	3.0 / 921	tilting	n	1/8000s	5.0/s	n	n
13.		Sony A7S III	9440	n	3.0 / 1440	swivel	Y	1/8000s	10.0/s	n	Y
14.		Sony A9 II	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
15.		Sony A99	2359	Y	3.0 / 1229	full-flex	n	1/8000s	6.0/s	n	Y
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One differentiating feature between the two cameras concerns the touch sensitivity of the rear screen. The A9 has a touchscreen, while the A7S II has a conventional panel. Touch control can be particularly helpful, for example, for setting the focus point.

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).

Concerning the storage of imaging data, both the A9 and the A7S II write their files to SDXC or Memory Stick PRO Duo cards. The A9 features dual card slots, which can be very useful in case a memory card fails. In contrast, the A7S II only has one slot. The A9 supports UHS-II cards (on its first slot), while the A7S II can use UHS-I cards.

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 Sony Alpha A9 and Sony Alpha 7S 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.		Sony A9	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	Y
2.		Sony A7S II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
3.		Nikon Z6	Y	stereo / mono	Y	Y	micro	3.1	Y	-	Y
4.		Sony A7 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
5.		Sony A7 III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
6.		Sony A7 IV	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
7.		Sony A7R II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
8.		Sony A7R III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
9.		Sony A7R IIIA	Y	stereo / mono	Y	Y	micro	3.2	Y	Y	Y
10.		Sony A7R IV	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
11.		Sony A7R V	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
12.		Sony A7S	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
13.		Sony A7S III	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
14.		Sony A9 II	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
15.		Sony A99	Y	stereo / mono	Y	Y	mini	2.0	-	-	-

Studio photographers will appreciate that the Sony A9 (unlike the A7S II) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the A9 and the A7S II have been discontinued, but can regularly be found used on ebay. The A7S II was replaced by the Sony A7S III, while the A9 was followed by the Sony A9 II. Further information on the features and operation of the A9 and A7S II can be found, respectively, in the Sony A9 Manual (free pdf) or the online Sony A7S II Manual.

Review summary

So what conclusions can be drawn? Is there a clear favorite between the Sony A9 and the Sony A7S II? Which camera is better? Below is a summary of the relative strengths of each of the two contestants.

Arguments in favor of the Sony Alpha A9:

• More detail: Offers more megapixels (24 vs 12MP) with a 41% higher linear resolution.
• Better image quality: Scores markedly higher (7 points) in the DXO overall assessment.
• Richer colors: Generates images with noticeably better colors (1.3 bits more color depth).
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• More detailed viewfinder: Has higher resolution electronic viewfinder (3686k vs 2400k dots).
• More detailed LCD: Has a higher resolution rear screen (1440k vs 1229k dots).
• Fewer buttons to press: Is equipped with a touch-sensitive rear screen to facilitate handling.
• Faster burst: Shoots at higher frequency (20 vs 5 flaps/sec) to capture the decisive moment.
• Longer lasting: Can take more shots (650 versus 370) on a single battery charge.
• Easier wireless transfer: Supports Bluetooth for image sharing without cables.
• Better studio light control: Has a PC Sync socket to connect to professional strobe lights.
• Greater peace of mind: Features a second card slot as a backup in case of memory card failure.
• Faster buffer clearing: Supports a more advanced SD data transfer standard (UHS-II vs UHS-I).
• More modern: Is somewhat more recent (announced 1 year and 7 months after the A7S II).

Advantages of the Sony Alpha 7S II:

• More affordable: Was introduced into a lower priced category (33 percent cheaper at launch).
• More heavily discounted: Has been on the market for longer (launched in September 2015).

If the count of individual advantages (bullet points above) is taken as a guide, the A9 is the clear winner of the match-up (14 : 2 points). However, the relevance of individual strengths will vary across photographers, so that you might want to apply your own weighing scheme to the summary points when reflecting and deciding 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 Sony A9 and the Sony A7S 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 the spec-sheets of cameras can offer a general idea of their imaging potential, it says little about, for example, the shooting experience and imaging performance of the A9 and the A7S II 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 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.		Sony A9	5/5	+ +	4.8/5	89/100	5/5	5/5	Apr 2017	4,499	ebay.com
2.		Sony A7S II	5/5	+	..	..	4.5/5	5/5	Sep 2015	2,999	ebay.com
3.		Nikon Z6	5/5	..	5/5	89/100	4.5/5	5/5	Aug 2018	1,999	ebay.com
4.		Sony A7 II	5/5	+	4/5	82/100	4.5/5	5/5	Nov 2014	1,999	ebay.com
5.		Sony A7 III	..	+ +	4.5/5	89/100	5/5	5/5	Feb 2018	1,999	amazon.com
6.		Sony A7 IV	5/5	+ +	4.5/5	89/100	4.5/5	4.5/5	Oct 2021	2,499	amazon.com
7.		Sony A7R II	5/5	+ +	5/5	90/100	5/5	5/5	Jun 2015	3,199	ebay.com
8.		Sony A7R III	..	+ +	4/5	90/100	4.5/5	5/5	Oct 2017	3,199	ebay.com
9.		Sony A7R IIIA	..	+ +	4/5	90/100	4.5/5	5/5	Apr 2021	3,199	amazon.com
10.		Sony A7R IV	5/5	+	4.5/5	91/100	4.5/5	5/5	Jul 2019	3,499	ebay.com
11.		Sony A7R V	5/5	+ +	4.5/5	92/100	..	..	Oct 2022	3,899	amazon.com
12.		Sony A7S	4/5	..	..	86/100	4.5/5	5/5	Apr 2014	2,499	ebay.com
13.		Sony A7S III	4.5/5	+ +	5/5	91/100	4.5/5	5/5	Jul 2020	3,499	amazon.com
14.		Sony A9 II	..	..	5/5	90/100	5/5	5/5	Oct 2019	4,499	amazon.com
15.		Sony A99	5/5	..	..	84/100	4.5/5	4.5/5	Sep 2012	2,799	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

Care should be taken when interpreting the review scores above, 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, kindly note that some of the listed sites have over time developped their review approaches and their reporting style.

Check A9 offers at
ebay.com
Check A7S II offers at
ebay.com

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.

~

Check A9 offers at
ebay.com
Check A7S II offers at
ebay.com

Did you notice an error on this page? If so, please get in touch, so that we can correct the information.