Sony A6400 vs A99

The Sony Alpha A6400 and the Sony Alpha SLT-A99 are two digital cameras that were officially introduced, respectively, in January 2019 and September 2012. The A6400 is a mirrorless interchangeable lens camera, while the A99 is a DSLR. The cameras are based on an APS-C (A6400) and a full frame (A99) 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 A99
Mirrorless system camera		Digital single lens reflex
Sony E mount lenses		Sony A mount lenses
24 MP – APS-C sensor		24 MP – Full Frame sensor
4K/30p Video		1080/60p Video
ISO 100-32,000 (100 - 102,400)		ISO 100-25,600
Electronic viewfinder (2359k dots)		Electronic viewfinder (2359k dots)
3.0" LCD – 922k dots		3.0" LCD – 1229k dots
Tilting touchscreen		Fully flexible screen (no touchscreen)
11 shutter flaps per second		6 shutter flaps per second
Lens stabilization only		In-body stabilization
Weathersealed body		Weathersealed body
410 shots per battery charge		500 shots per battery charge
120 x 67 x 50 mm, 403 g		147 x 111 x 78 mm, 812 g

Check A6400 price at
amazon.com
Check A99 offers at
ebay.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Sony Alpha A6400 and the Sony Alpha SLT-A99? 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 side-by-side display below illustrates the physical size and weight of the Sony A6400 and the Sony A99. 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 A99 is considerably larger (103 percent) than the Sony A6400. Moreover, the A99 is substantially heavier (101 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. 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 A6400 gets 410 shots out of its Sony NP-FW50 battery, while the A99 can take 500 images on a single charge of its Sony NP-FM500H power pack. The power pack in the A6400 can be charged via the USB port, so that it is not always necessary to take the battery charger along when travelling.

The adjacent table lists the principal physical characteristics of the two cameras alongside a wider set of alternatives. 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 A6400	120 mm	67 mm	50 mm	403 g	410	Y	Jan 2019	899	amazon.com
2.		Sony A99	147 mm	111 mm	78 mm	812 g	500	Y	Sep 2012	2,799	ebay.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 A9 II	129 mm	96 mm	76 mm	678 g	690	Y	Oct 2019	4,499	amazon.com
6.		Sony A77	143 mm	104 mm	81 mm	732 g	470	Y	Aug 2011	1,399	ebay.com
7.		Sony A99 II	143 mm	104 mm	76 mm	849 g	490	Y	Sep 2016	3,199	ebay.com
8.		Sony A850	156 mm	117 mm	82 mm	895 g	880	Y	Aug 2009	1,999	ebay.com
9.		Sony A900	156 mm	117 mm	82 mm	895 g	880	Y	Sep 2008	2,999	ebay.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 naturally be influenced heavily by the price. 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 A6400 was launched at a markedly lower price (by 68 percent) than the A99, 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 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 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 A99 a full frame sensor. The sensor area in the A99 is 132 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 A99 has a larger sensor, both cameras offer the same resolution of 24 megapixels. This implies that the A99 has a lower pixel density and larger individual pixels (with a pixel pitch of 5.96μm versus 3.91μm for the A6400), which gives it a potential advantage in terms of light gathering capacity. It should, however, be noted that the A6400 is much more recent (by 6 years and 4 months) than the A99, and its sensor will have benefitted from technological advances during this time that at least partly compensate for the smaller pixel size.

The A6400 has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

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 SLT-A99 are ISO 100 to ISO 25600, with the possibility to increase the ISO range to 50-25600.

Technology-wise, both cameras are equipped with CMOS (Complementary Metal–Oxide–Semiconductor) sensors. 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 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"). Of the two cameras under consideration, the A99 has a markedly higher DXO score than the A6400 (overall score 6 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 0.1 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 A6400	APS-C	24.0	6000	4000	4K/30p	24.0	13.6	1431	83
2.		Sony A99	Full Frame	24.0	6000	4000	1080/60p	25.0	14.0	1555	89
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 A9 II	Full Frame	24.0	6000	4000	4K/30p	25.0	14.0	3434	93
6.		Sony A77	APS-C	24.0	6000	4000	1080/60p	24.0	13.2	801	78
7.		Sony A99 II	Full Frame	42.2	7952	5304	4K/30p	25.4	13.4	2317	92
8.		Sony A850	Full Frame	24.4	6048	4032	none	23.8	12.2	1415	79
9.		Sony A900	Full Frame	24.4	6048	4032	none	23.7	12.3	1431	79
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. The two cameras under consideration both have sensors whose read-out speed is fast enough to capture moving pictures, but the A6400 provides a higher video resolution than the A99. It can shoot video footage at 4K/30p, while the A99 is limited to 1080/60p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. The A6400 and the A99 are similar in the sense that both feature an electronic viewfinder, which is helpful when framing images in bright sunlight. Moreover, their viewfinders offer an identical resolution of 2359k dots. The table below summarizes some of the other core capabilities of the Sony A6400 and Sony A99 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 A99	2359	Y	3.0 / 1229	full-flex	n	1/8000s	6.0/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 A9 II	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
6.		Sony A77	2359	Y	3.0 / 921	full-flex	n	1/8000s	12.0/s	Y	Y
7.		Sony A99 II	2400	Y	3.0 / 1229	full-flex	n	1/8000s	12.0/s	n	Y
8.		Sony A850	optical	Y	3.0 / 922	fixed	n	1/8000s	3.0/s	n	Y
9.		Sony A900	optical	Y	3.0 / 922	fixed	n	1/8000s	5.0/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 A99 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, the A6400 is one of those camera that have an additional 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 A6400 and the A99 write their files to SDXC or Memory Stick PRO Duo cards. The A99 features dual card slots, which can be very useful in case a memory card fails. In contrast, the A6400 only has one slot. Both cameras can use UHS-I cards, which provide for Ultra High Speed data transfer of up to 104 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 Sony Alpha A6400 and Sony Alpha SLT-A99 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 A99	Y	stereo / mono	Y	Y	mini	2.0	-	-	-
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 A9 II	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
6.		Sony A77	Y	stereo / mono	Y	-	mini	2.0	-	-	-
7.		Sony A99 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	Y
8.		Sony A850	Y	- / -	-	-	mini	2.0	-	-	-
9.		Sony A900	Y	- / -	-	-	mini	2.0	-	-	-
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 A6400 offers wifi support, while the A99 does not. Wifi can be a very convenient means to transfer image data to an off-camera location.

Studio photographers will appreciate that the Sony A99 (unlike the A6400) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Travel and landscape photographers will find it useful that the A99 has an internal geolocalization sensor and can record GPS coordinates in its EXIF data.

The A6400 is a recent model that features in the current product line-up of Sony. In contrast, the A99 has been discontinued (but can be found pre-owned on ebay). As a replacement in the same line of cameras, the A99 was succeeded by the Sony A99. Further information on the features and operation of the A6400 and A99 can be found, respectively, in the Sony A6400 Manual (free pdf) or the online Sony A99 Manual.

Review summary

So what conclusions can be drawn? Which of the two cameras – the Sony A6400 or the Sony A99 – 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.

Advantages of the Sony Alpha A6400:

• Better video: Provides higher definition movie capture (4K/30p vs 1080/60p).
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• Fewer buttons to press: Is equipped with a touch-sensitive rear screen to facilitate handling.
• Faster burst: Shoots at higher frequency (11 vs 6 flaps/sec) to capture the decisive moment.
• Less disturbing: Has an electronic shutter option for completely silent shooting.
• More compact: Is smaller (120x67mm vs 147x111mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 409g or 50 percent) and hence easier to carry around.
• Easier travel charging: Can be conveniently charged via its USB port.
• More legacy lens friendly: Can take a broad range of non-native lenses via adapters.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• Easier file upload: Has wifi built in for automatic backup or image transfer to the web.
• Easier device pairing: Supports NFC for fast wireless image transfer over short distances.
• Easier wireless transfer: Supports Bluetooth for image sharing without cables.
• More affordable: Was introduced into a lower priced category (68 percent cheaper at launch).
• More modern: Reflects 6 years and 4 months of technical progress since the A99 launch.

Reasons to prefer the Sony Alpha SLT-A99:

• Better image quality: Scores markedly higher (6 points) in the DXO overall evaluation.
• Better sound control: Has a headphone port that enables audio monitoring while recording.
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.71x vs 0.70x).
• Easier setting verification: Features a control panel on top to check shooting parameters.
• More detailed LCD: Has a higher resolution rear screen (1229k vs 922k dots).
• More flexible LCD: Has a full-flex 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 (500 versus 410) out of a single battery charge.
• Sharper images: Has stabilization technology built-in to reduce the impact of hand-shake.
• Easier geotagging: Features an internal GPS sensor to log localization data.
• 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.
• More heavily discounted: Has been around for much longer (launched in September 2012).

If the count of relative strengths (bullet points above) is taken as a measure, the A6400 emerges as the winner of the contest (15 : 13 points). 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 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 A99 place the cameras among the top in their class? Find out in the latest Best Mirrorless Interchangeable Lens Camera and Best DSLR Camera listings 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 says little about, for example, the shooting experience and imaging performance of the A6400 and the A99 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 (USD)	Street Price
1.		Sony A6400	4/5	+	4/5	85/100	4.5/5	4/5	Jan 2019	899	amazon.com
2.		Sony A99	5/5	..	..	84/100	4.5/5	4.5/5	Sep 2012	2,799	ebay.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 A9 II	..	..	5/5	90/100	5/5	5/5	Oct 2019	4,499	amazon.com
6.		Sony A77	5/5	91/100	..	81/100	..	5/5	Aug 2011	1,399	ebay.com
7.		Sony A99 II	..	..	4.5/5	85/100	4.5/5	4.5/5	Sep 2016	3,199	ebay.com
8.		Sony A850	3/5	..	..	75/100	..	4.5/5	Aug 2009	1,999	ebay.com
9.		Sony A900	..	+ +	..	+ +	4.5/5	5/5	Sep 2008	2,999	ebay.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.

The review scores listed above should be treated with care, though. The ratings are only valid when referring to cameras in the same category and of the same age. 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. Also, please note that some of the review sites have changed their methodology and reporting over time.

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Other camera comparisons

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