Sony A6400 vs A9 II

The Sony Alpha A6400 and the Sony Alpha A9 II are two digital cameras that were officially introduced, respectively, in January 2019 and October 2019. Both the A6400 and the A9 II are mirrorless interchangeable lens cameras that are based on an APS-C (A6400) and a full frame (A9 II) 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

Sony A6400		Sony A9 II
Mirrorless system camera		Mirrorless system camera
Sony E mount lenses		Sony E mount lenses
24 MP – APS-C sensor		24 MP – Full Frame sensor
4K/30p Video		4K/30p Video
ISO 100-32,000 (100 - 102,400)		ISO 100-51,200 (50 - 204,800)
Electronic viewfinder (2359k dots)		Electronic viewfinder (3686k dots)
3.0" LCD – 922k dots		3.0" LCD – 1440k dots
Tilting touchscreen		Tilting touchscreen
11 shutter flaps per second		20 shutter flaps per second
Lens stabilization only		In-body stabilization
Weathersealed body		Weathersealed body
410 shots per battery charge		690 shots per battery charge
120 x 67 x 50 mm, 403 g		129 x 96 x 76 mm, 678 g

Check A6400 price at
amazon.com
Check A9 II 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 A9 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

An illustration of the physical size and weight of the Sony A6400 and the Sony A9 II is provided in the side-by-side display below. 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 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 II is considerably larger (54 percent) than the Sony A6400. Moreover, the A9 II is substantially heavier (68 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 (A9 II). 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 A9 II can take 690 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 A9 II	129 mm	96 mm	76 mm	678 g	690	Y	Oct 2019	4,499	amazon.com
3.		Canon 2000D	129 mm	101 mm	78 mm	475 g	500	n	Feb 2018	449	amazon.com
4.		Canon M5	116 mm	89 mm	61 mm	427 g	295	n	Sep 2016	979	ebay.com
5.		Canon M50	116 mm	88 mm	59 mm	390 g	235	n	Feb 2018	779	ebay.com
6.		Leica C-LUX	113 mm	67 mm	46 mm	340 g	370	n	Jun 2018	1,049	ebay.com
7.		Sony A7 III	127 mm	96 mm	74 mm	650 g	610	Y	Feb 2018	1,999	amazon.com
8.		Sony A7C	124 mm	71 mm	60 mm	509 g	740	Y	Sep 2020	1,799	amazon.com
9.		Sony A7R IV	129 mm	96 mm	78 mm	665 g	670	Y	Jul 2019	3,499	ebay.com
10.		Sony A7S III	127 mm	97 mm	81 mm	699 g	600	Y	Jul 2020	3,499	amazon.com
11.		Sony A9	127 mm	96 mm	63 mm	673 g	650	Y	Apr 2017	4,499	ebay.com
12.		Sony A3000	128 mm	91 mm	85 mm	411 g	470	n	Aug 2013	329	ebay.com
13.		Sony A6000	120 mm	67 mm	45 mm	344 g	360	n	Feb 2014	599	ebay.com
14.		Sony A6100	120 mm	67 mm	59 mm	396 g	420	n	Aug 2019	749	ebay.com
15.		Sony A6300	120 mm	67 mm	49 mm	404 g	400	Y	Feb 2016	999	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 80 percent) than the A9 II, 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 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. 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 A9 II a full frame sensor. The sensor area in the A9 II 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.

Even though the A9 II has a larger sensor, both cameras offer the same resolution of 24 megapixels. This implies that the A9 II has a lower pixel density and larger individual pixels (with a pixel pitch of 5.94μm versus 3.91μm for the A6400), which gives it a potential advantage in terms of light gathering capacity. In addition, the A9 II is a somewhat more recent model (by 8 months) than the A6400, and its sensor might have benefitted from technological advances during this time.

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 A9 II are ISO 100 to ISO 51200, with the possibility to increase the ISO range to 50-204800.

In terms of underlying technology, the A6400 is build around a CMOS sensor, while the A9 II uses a Stacked 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.

For many cameras, data on sensor performance has been reported by DXO Mark. 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 consideration, the A9 II has a markedly higher DXO score than the A6400 (overall score 10 points higher), which will translate into better image quality. The advantage is based on 1 bits higher color depth, 0.4 EV in additional dynamic range, and 1.3 stops in additional low light sensitivity. 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.		Sony A6400	APS-C	24.0	6000	4000	4K/30p	24.0	13.6	1431	83
2.		Sony A9 II	Full Frame	24.0	6000	4000	4K/30p	25.0	14.0	3434	93
3.		Canon 2000D	APS-C	24.0	6000	4000	1080/30p	22.6	11.9	1009	71
4.		Canon M5	APS-C	24.0	6000	4000	1080/60p	23.4	12.4	1262	77
5.		Canon M50	APS-C	24.0	6000	4000	4K/24p	23.8	13.3	1684	81
6.		Leica C-LUX	1-inch	20.0	5472	3648	4K/30p	22.1	12.3	481	64
7.		Sony A7 III	Full Frame	24.0	6000	4000	4K/30p	25.0	14.7	3730	96
8.		Sony A7C	Full Frame	24.0	6000	4000	4K/30p	25.0	14.7	3407	95
9.		Sony A7R IV	Full Frame	60.2	9504	6336	4K/30p	26.0	14.8	3344	99
10.		Sony A7S III	Full Frame	12.0	4240	2832	4K/120p	23.7	13.9	2520	86
11.		Sony A9	Full Frame	24.0	6000	4000	4K/30p	24.9	13.3	3517	92
12.		Sony A3000	APS-C	19.8	5456	3632	1080/60i	23.7	12.8	1068	78
13.		Sony A6000	APS-C	24.0	6000	4000	1080/60p	24.1	13.1	1347	82
14.		Sony A6100	APS-C	24.0	6000	4000	4K/30p	24.1	13.6	1947	84
15.		Sony A6300	APS-C	24.0	6000	4000	4K/30p	24.4	13.7	1437	85
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, and both provide the same movie specifications (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 A9 II offers a substantially higher resolution than the one in the A6400 (3686k vs 2359k dots). The table below summarizes some of the other core capabilities of the Sony A6400 and Sony A9 II in connection with corresponding information for a sample of similar 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.		Sony A6400	2359	n	3.0 / 922	tilting	Y	1/4000s	11.0/s	Y	n
2.		Sony A9 II	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
3.		Canon 2000D	optical	n	3.0 / 920	fixed	n	1/4000s	3.0/s	Y	n
4.		Canon M5	2360	n	3.2 / 1620	tilting	Y	1/4000s	9.0/s	Y	n
5.		Canon M50	2360	n	3.0 / 1040	swivel	Y	1/4000s	10.0/s	Y	n
6.		Leica C-LUX	2330	n	3.0 / 1240	fixed	Y	1/2000s	10.0/s	Y	Y
7.		Sony A7 III	2359	n	3.0 / 922	tilting	Y	1/8000s	10.0/s	n	Y
8.		Sony A7C	2360	n	3.0 / 922	swivel	Y	1/4000s	10.0/s	n	Y
9.		Sony A7R IV	5760	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
10.		Sony A7S III	9440	n	3.0 / 1440	swivel	Y	1/8000s	10.0/s	n	Y
11.		Sony A9	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
12.		Sony A3000	202	n	3.0 / 230	fixed	n	1/4000s	2.5/s	Y	n
13.		Sony A6000	1440	n	3.0 / 922	tilting	n	1/4000s	11.0/s	Y	n
14.		Sony A6100	1440	n	3.0 / 922	tilting	Y	1/4000s	11.0/s	Y	n
15.		Sony A6300	2359	n	3.0 / 922	tilting	n	1/4000s	11.0/s	Y	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 A9 II 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 Sony A9 II 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 A6400 writes its imaging data to SDXC or Memory Stick PRO Duo cards, while the A9 II uses SDXC cards. The A9 II features dual card slots, which can be very useful in case a memory card fails. In contrast, the A6400 only has one slot. The A9 II 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 A9 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 A6400	Y	stereo / mono	Y	-	micro	2.0	Y	Y	Y
2.		Sony A9 II	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
3.		Canon 2000D	Y	mono / mono	-	-	mini	2.0	Y	Y	-
4.		Canon M5	Y	stereo / mono	Y	-	mini	2.0	Y	Y	Y
5.		Canon M50	Y	stereo / mono	Y	-	micro	2.0	Y	-	Y
6.		Leica C-LUX	-	stereo / mono	-	-	micro	2.0	Y	-	-
7.		Sony A7 III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
8.		Sony A7C	Y	stereo / mono	Y	Y	micro	3.2	Y	Y	Y
9.		Sony A7R IV	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
10.		Sony A7S III	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
11.		Sony A9	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	Y
12.		Sony A3000	Y	stereo / mono	-	-	mini	2.0	-	-	-
13.		Sony A6000	Y	stereo / mono	-	-	micro	2.0	Y	Y	-
14.		Sony A6100	Y	stereo / mono	Y	-	micro	2.0	Y	Y	Y
15.		Sony A6300	Y	stereo / mono	Y	-	micro	2.0	Y	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 A9 II 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.

Studio photographers will appreciate that the Sony A9 II (unlike the A6400) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the A6400 and the A9 II are recent models that are part of the current product line-up. The A6400 replaced the earlier Sony A6300, while the A9 II followed on from the Sony A9. Further information on the features and operation of the A6400 and A9 II can be found, respectively, in the Sony A6400 Manual (free pdf) or the online Sony A9 II Manual.

Review summary

So what conclusions can be drawn? Is the Sony A6400 better than the Sony A9 II or vice versa? The listing below highlights the relative strengths of the two models.

Advantages of the Sony Alpha A6400:

• More selfie-friendly: Has an articulated screen that can be turned to be front-facing.
• More compact: Is smaller (120x67mm vs 129x96mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 275g or 41 percent) and hence easier to carry around.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• More affordable: Was introduced into a lower priced category (80 percent cheaper at launch).
• More heavily discounted: Has been on the market for longer (launched in January 2019).

Reasons to prefer the Sony Alpha A9 II:

• Better image quality: Scores markedly higher (10 points) in the DXO overall evaluation.
• Better low-light sensitivity: Can shoot in dim conditions (1.3 stops ISO advantage).
• Better sound control: Has a headphone port that enables audio monitoring while recording.
• More detailed viewfinder: Has higher resolution electronic viewfinder (3686k vs 2359k dots).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.78x vs 0.70x).
• More detailed LCD: Has a higher resolution rear screen (1440k vs 922k dots).
• Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
• Faster burst: Shoots at higher frequency (20 vs 11 flaps/sec) to capture the decisive moment.
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• Longer lasting: Gets more shots (690 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 (3.1 vs 2.0).
• 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: Was introduced somewhat (8 months) more recently.

If the number of relative strengths (bullet points above) is taken as a guide, the A9 II is the clear winner of the contest (16 : 6 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 A9 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 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 A6400 or the A9 II perform in practice. User reviews that are available, for instance, at amazon can sometimes shed light on these issues, but such feedback is all too often partial, inconsistent, and inaccurate.

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 A9 II	..	..	5/5	90/100	5/5	5/5	Oct 2019	4,499	amazon.com
3.		Canon 2000D	3/5	o	3.5/5	..	3.5/5	3.5/5	Feb 2018	449	amazon.com
4.		Canon M5	4/5	+	4/5	82/100	4/5	4/5	Sep 2016	979	ebay.com
5.		Canon M50	..	+	4/5	79/100	..	3.5/5	Feb 2018	779	ebay.com
6.		Leica C-LUX	..	..	3.5/5	..	4.5/5	4/5	Jun 2018	1,049	ebay.com
7.		Sony A7 III	..	+ +	4.5/5	89/100	5/5	5/5	Feb 2018	1,999	amazon.com
8.		Sony A7C	3.5/5	..	3.5/5	86/100	4/5	4/5	Sep 2020	1,799	amazon.com
9.		Sony A7R IV	5/5	+	4.5/5	91/100	4.5/5	5/5	Jul 2019	3,499	ebay.com
10.		Sony A7S III	4.5/5	+ +	5/5	91/100	4.5/5	5/5	Jul 2020	3,499	amazon.com
11.		Sony A9	5/5	+ +	4.8/5	89/100	5/5	5/5	Apr 2017	4,499	ebay.com
12.		Sony A3000	3/5	+	..	..	4/5	4/5	Aug 2013	329	ebay.com
13.		Sony A6000	5/5	+	4.5/5	80/100	4.5/5	5/5	Feb 2014	599	ebay.com
14.		Sony A6100	..	..	4/5	82/100	4/5	5/5	Aug 2019	749	ebay.com
15.		Sony A6300	4.5/5	+	..	85/100	5/5	5/5	Feb 2016	999	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.

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 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 A6400 price at
amazon.com
Check A9 II price at
amazon.com

Other camera comparisons

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