Sony A6400 vs A7S III

The Sony Alpha A6400 and the Sony Alpha 7S III are two digital cameras that were revealed to the public, respectively, in January 2019 and July 2020. Both the A6400 and the A7S III are mirrorless interchangeable lens cameras that are based on an APS-C (A6400) and a full frame (A7S III) sensor. The A6400 has a resolution of 24 megapixels, whereas the A7S III 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 A6400		Sony A7S III
Mirrorless system camera		Mirrorless system camera
Sony E mount lenses		Sony E mount lenses
24 MP – APS-C sensor		12 MP – Full Frame sensor
4K/30p Video		4K/120p Video
ISO 100-32,000 (100 - 102,400)		ISO 80-102,400 (40 - 409,600)
Electronic viewfinder (2359k dots)		Electronic viewfinder (9440k dots)
3.0" LCD – 922k dots		3.0" LCD – 1440k dots
Tilting touchscreen		Swivel touchscreen
11 shutter flaps per second		10 shutter flaps per second
Lens stabilization only		In-body stabilization
Weathersealed body		Weathersealed body
410 shots per battery charge		600 shots per battery charge
120 x 67 x 50 mm, 403 g		127 x 97 x 81 mm, 699 g

Check A6400 price at
amazon.com
Check A7S III price at
amazon.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Sony Alpha A6400 and the Sony Alpha 7S 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 Sony A6400 and the Sony A7S 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 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 A7S III is considerably larger (53 percent) than the Sony A6400. Moreover, the A7S III is substantially heavier (73 percent) than the A6400. 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 Sony E-Mount Lens Catalog (A6400) and the Sony FE Lens Catalog (A7S III). 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 A6400 gets 410 shots out of its Sony NP-FW50 battery, while the A7S III can take 600 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 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.		Sony A6400	120 mm	67 mm	50 mm	403 g	410	Y	Jan 2019	899	amazon.com
2.		Sony A7S III	127 mm	97 mm	81 mm	699 g	600	Y	Jul 2020	3,499	amazon.com
3.		Fujifilm X-T30	118 mm	83 mm	47 mm	383 g	380	n	Feb 2019	899	ebay.com
4.		Nikon D5300	125 mm	98 mm	76 mm	480 g	600	n	Oct 2013	799	ebay.com
5.		Sony A7R III	127 mm	96 mm	74 mm	650 g	650	Y	Oct 2017	3,199	ebay.com
6.		Sony A7R IV	129 mm	96 mm	78 mm	665 g	670	Y	Jul 2019	3,499	ebay.com
7.		Sony A7R IVA	129 mm	96 mm	78 mm	665 g	670	Y	Apr 2021	3,499	amazon.com
8.		Sony A7S II	127 mm	96 mm	60 mm	627 g	370	Y	Sep 2015	2,999	ebay.com
9.		Sony A9 II	129 mm	96 mm	76 mm	678 g	690	Y	Oct 2019	4,499	amazon.com
10.		Sony A3000	128 mm	91 mm	85 mm	411 g	470	n	Aug 2013	329	ebay.com
11.		Sony A5100	110 mm	63 mm	36 mm	283 g	400	n	Aug 2014	549	ebay.com
12.		Sony A6000	120 mm	67 mm	45 mm	344 g	360	n	Feb 2014	599	ebay.com
13.		Sony A6100	120 mm	67 mm	59 mm	396 g	420	n	Aug 2019	749	ebay.com
14.		Sony A6300	120 mm	67 mm	49 mm	404 g	400	Y	Feb 2016	999	ebay.com
15.		Sony NEX-5R	111 mm	59 mm	39 mm	276 g	330	n	Aug 2012	749	ebay.com
16.		Sony NEX-6	120 mm	67 mm	43 mm	345 g	360	n	Sep 2012	999	ebay.com
17.		Sony NEX-7	120 mm	67 mm	43 mm	400 g	430	n	Aug 2011	1,349	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

Any camera decision will obviously take relative prices into account. 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 A6400 was launched at a markedly lower price (by 74 percent) than the A7S III, 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. 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 are more costly to manufacture and tend to lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Sony A6400 features an APS-C sensor and the Sony A7S III a full frame sensor. The sensor area in the A7S III is 131 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.5 and 1.0. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

Technology-wise, the A7S III uses a more advanced image processing engine (BIONZ XR) than the A6400 (BIONZ X), with benefits for noise reduction, color accuracy, and processing speed.

Despite having a smaller sensor, the Sony A6400 offers a higher resolution of 24 megapixels, compared with 12 MP of the Sony A7S III. This megapixels advantage comes at the cost of a higher pixel density and a smaller size of the individual pixel (with a pixel pitch of 3.91μm versus 8.40μm for the A7S III). Moreover, it should be noted that the A7S III is a somewhat more recent model (by 1 year and 6 months) than the A6400, and its sensor might have benefitted from technological advances during this time that further enhance the light gathering capacity of its pixel-units.

The resolution advantage of the Sony A6400 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A6400 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 III 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 Sony Alpha A6400 has a native sensitivity range from ISO 100 to ISO 32000, which can be extended to ISO 100-102400. The corresponding ISO settings for the Sony Alpha 7S III are ISO 80 to ISO 102400, with the possibility to increase the ISO range to 40-409600.

In terms of underlying technology, the A6400 is build around a CMOS sensor, while the A7S III 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.

Consistent information on actual sensor performance is available from DXO Mark for many cameras. 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 Overall DXO ratings for the two cameras under consideration are close, suggesting that they provide similar imaging performance. The table below summarizes the physical sensor characteristics and sensor quality findings and compares them across a set of similar 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 A6400	APS-C	24.0	6000	4000	4K/30p	24.0	13.6	1431	83
2.		Sony A7S III	Full Frame	12.0	4240	2832	4K/120p	23.7	13.9	2520	86
3.		Fujifilm X-T30	APS-C	26.0	6240	4160	4K/30p	24.1	13.5	1895	83
4.		Nikon D5300	APS-C	24.0	6000	4000	1080/60p	24.0	13.9	1338	83
5.		Sony A7R III	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
6.		Sony A7R IV	Full Frame	60.2	9504	6336	4K/30p	26.0	14.8	3344	99
7.		Sony A7R IVA	Full Frame	60.2	9504	6336	4K/30p	26.0	14.8	3344	99
8.		Sony A7S II	Full Frame	12.0	4240	2832	4K/30p	23.6	13.3	2993	85
9.		Sony A9 II	Full Frame	24.0	6000	4000	4K/30p	25.0	14.0	3434	93
10.		Sony A3000	APS-C	19.8	5456	3632	1080/60i	23.7	12.8	1068	78
11.		Sony A5100	APS-C	24.0	6000	4000	1080/60p	23.8	12.7	1347	80
12.		Sony A6000	APS-C	24.0	6000	4000	1080/60p	24.1	13.1	1347	82
13.		Sony A6100	APS-C	24.0	6000	4000	4K/30p	24.1	13.6	1947	84
14.		Sony A6300	APS-C	24.0	6000	4000	4K/30p	24.4	13.7	1437	85
15.		Sony NEX-5R	APS-C	16.0	4912	3264	1080/60i	23.7	13.1	910	78
16.		Sony NEX-6	APS-C	16.0	4912	3264	1080/60i	23.7	13.1	1018	78
17.		Sony NEX-7	APS-C	24.0	6000	4000	1080/60i	24.1	13.4	1016	81
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 have a sensor with sufficiently fast read-out times for moving pictures, but the A7S III provides a faster frame rate than the A6400. It can shoot movie footage at 4K/120p, while the A6400 is limited to 4K/30p.

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 A7S III offers a substantially higher resolution than the one in the A6400 (9440k vs 2359k dots). The adjacent table lists some of the other core features of the Sony A6400 and Sony A7S III 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 A6400	2359	n	3.0 / 922	tilting	Y	1/4000s	11.0/s	Y	n
2.		Sony A7S III	9440	n	3.0 / 1440	swivel	Y	1/8000s	10.0/s	n	Y
3.		Fujifilm X-T30	2360	n	3.0 / 1040	tilting	Y	1/4000s	8.0/s	Y	n
4.		Nikon D5300	optical	n	3.2 / 1037	swivel	n	1/4000s	5.0/s	Y	n
5.		Sony A7R III	3686	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
6.		Sony A7R IV	5760	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
7.		Sony A7R IVA	5760	n	3.0 / 2340	tilting	Y	1/8000s	10.0/s	n	Y
8.		Sony A7S II	2400	n	3.0 / 1229	tilting	n	1/8000s	5.0/s	n	Y
9.		Sony A9 II	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
10.		Sony A3000	202	n	3.0 / 230	fixed	n	1/4000s	2.5/s	Y	n
11.		Sony A5100	none	n	3.0 / 922	tilting	Y	1/4000s	6.0/s	Y	n
12.		Sony A6000	1440	n	3.0 / 922	tilting	n	1/4000s	11.0/s	Y	n
13.		Sony A6100	1440	n	3.0 / 922	tilting	Y	1/4000s	11.0/s	Y	n
14.		Sony A6300	2359	n	3.0 / 922	tilting	n	1/4000s	11.0/s	Y	n
15.		Sony NEX-5R	optional	n	3.0 / 920	tilting	Y	1/4000s	10.0/s	n	n
16.		Sony NEX-6	2359	n	3.0 / 921	tilting	n	1/4000s	10.0/s	Y	n
17.		Sony NEX-7	2359	n	3.0 / 921	tilting	n	1/4000s	10.0/s	Y	n
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One difference between the cameras concerns the presence of an on-board flash. The A6400 has one, while the A7S III does not. While the built-in flash of the A6400 is not very powerful, it can at times be useful as a fill-in light.

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 A6400 writes its imaging data to SDXC or Memory Stick PRO Duo cards, while the A7S III uses CFexpress (type A) or SDXC cards. The A7S III features dual card slots, which can be very useful in case a memory card fails. In contrast, the A6400 only has one slot. The A7S III supports UHS-II cards (on both slots), while the A6400 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 A6400 and Sony Alpha 7S 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.		Sony A6400	Y	stereo / mono	Y	-	micro	2.0	Y	Y	Y
2.		Sony A7S III	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
3.		Fujifilm X-T30	Y	stereo / mono	Y	-	micro	3.1	Y	-	Y
4.		Nikon D5300	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
5.		Sony A7R III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
6.		Sony A7R IV	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
7.		Sony A7R IVA	Y	stereo / mono	Y	Y	micro	3.2	Y	Y	Y
8.		Sony A7S II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
9.		Sony A9 II	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
10.		Sony A3000	Y	stereo / mono	-	-	mini	2.0	-	-	-
11.		Sony A5100	-	stereo / mono	-	-	micro	2.0	Y	Y	-
12.		Sony A6000	Y	stereo / mono	-	-	micro	2.0	Y	Y	-
13.		Sony A6100	Y	stereo / mono	Y	-	micro	2.0	Y	Y	Y
14.		Sony A6300	Y	stereo / mono	Y	-	micro	2.0	Y	Y	-
15.		Sony NEX-5R	Y	stereo / mono	-	-	mini	2.0	Y	-	-
16.		Sony NEX-6	Y	stereo / mono	-	-	mini	2.0	Y	-	-
17.		Sony NEX-7	Y	stereo / mono	Y	-	mini	2.0	-	-	-

It is notable that the A7S III has a headphone jack, which makes it possible to attach external headphones and monitor the quality of sound during the recording process. The A6400 lacks such a headphone port.

Both the A6400 and the A7S III are recent models that are part of the current product line-up. The A6400 replaced the earlier Sony A6300, while the A7S III followed on from the Sony A7S II. Further information on the features and operation of the A6400 and A7S III can be found, respectively, in the Sony A6400 Manual (free pdf) or the online Sony A7S III Manual.

Review summary

So how do things add up? Is there a clear favorite between the Sony A6400 and the Sony A7S III? 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 A6400:

• More detail: Offers more megapixels (24 vs 12MP) with a 41% higher linear resolution.
• More compact: Is smaller (120x67mm vs 127x97mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 296g or 42 percent) and hence easier to carry around.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• Easier device pairing: Supports NFC for fast wireless image transfer over short distances.
• More affordable: Was introduced into a lower priced category (74 percent cheaper at launch).
• More heavily discounted: Has been on the market for longer (launched in January 2019).

Advantages of the Sony Alpha 7S III:

• Better low-light sensitivity: Can shoot in dim conditions (0.8 stops ISO advantage).
• Better jpgs: Has a more modern image processing engine (BIONZ XR vs BIONZ X).
• Better video: Provides higher movie framerates (4K/120p versus 4K/30p).
• Better sound control: Has a headphone port that enables audio monitoring while recording.
• More detailed viewfinder: Has higher resolution electronic viewfinder (9440k vs 2359k dots).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.91x vs 0.70x).
• More detailed LCD: Has a higher resolution rear screen (1440k vs 922k dots).
• More flexible LCD: Has a swivel screen for odd-angle shots in portrait or landscape orientation.
• Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
• Longer lasting: Gets more shots (600 versus 410) out of a single battery charge.
• Sharper images: Has stabilization technology built-in to reduce the impact of hand-shake.
• Faster data transfer: Supports a more advanced USB protocol (3.2 vs 2.0).
• More solid recording: Has a full-sized HDMI port for a sturdy connection to an external recorder.
• 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: Was introduced somewhat (1 year and 6 months) more recently.

If the count of individual advantages (bullet points above) is taken as a guide, the A7S III is the clear winner of the contest (16 : 7 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 wedding photographer will view the differences between cameras in a way that diverges from the perspective of a travel photog, and a person interested in cityscapes has distinct needs from a macro 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 A6400 and the Sony A7S 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 specs-based evaluation of cameras can be instructive in revealing their potential as photographic tools, it remains partial and cannot reveal, for example, the shooting experience and imaging performance when actually working with the A6400 or the A7S III. 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.		Sony A6400	4/5	+	4/5	85/100	4.5/5	4/5	Jan 2019	899	amazon.com
2.		Sony A7S III	4.5/5	+ +	5/5	91/100	4.5/5	5/5	Jul 2020	3,499	amazon.com
3.		Fujifilm X-T30	5/5	+ +	5/5	84/100	4.5/5	4.5/5	Feb 2019	899	ebay.com
4.		Nikon D5300	4/5	+ +	..	79/100	4.5/5	4.5/5	Oct 2013	799	ebay.com
5.		Sony A7R III	..	+ +	4/5	90/100	4.5/5	5/5	Oct 2017	3,199	ebay.com
6.		Sony A7R IV	5/5	+	4.5/5	91/100	4.5/5	5/5	Jul 2019	3,499	ebay.com
7.		Sony A7R IVA	5/5	+	4.5/5	91/100	4.5/5	5/5	Apr 2021	3,499	amazon.com
8.		Sony A7S II	5/5	+	..	..	4.5/5	5/5	Sep 2015	2,999	ebay.com
9.		Sony A9 II	..	..	5/5	90/100	5/5	5/5	Oct 2019	4,499	amazon.com
10.		Sony A3000	3/5	+	..	..	4/5	4/5	Aug 2013	329	ebay.com
11.		Sony A5100	4.5/5	+	..	..	4.5/5	5/5	Aug 2014	549	ebay.com
12.		Sony A6000	5/5	+	4.5/5	80/100	4.5/5	5/5	Feb 2014	599	ebay.com
13.		Sony A6100	..	..	4/5	82/100	4/5	5/5	Aug 2019	749	ebay.com
14.		Sony A6300	4.5/5	+	..	85/100	5/5	5/5	Feb 2016	999	ebay.com
15.		Sony NEX-5R	..	..	..	..	4.5/5	4.5/5	Aug 2012	749	ebay.com
16.		Sony NEX-6	5/5	+ +	..	78/100	4.5/5	4.5/5	Sep 2012	999	ebay.com
17.		Sony NEX-7	5/5	+ +	..	81/100	4.5/5	5/5	Aug 2011	1,349	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. Thus, a score needs to be put into the context of the launch date and the launch price 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.

Check A6400 price at
amazon.com
Check A7S III price at
amazon.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 use the search menu below. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored.

~

Check A6400 price at
amazon.com
Check A7S III price at
amazon.com

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