Sony A9 III vs A99

The Sony Alpha A9 III and the Sony Alpha SLT-A99 are two professional cameras that were revealed to the public, respectively, in November 2023 and September 2012. The A9 III is a mirrorless interchangeable lens camera, while the A99 is a DSLR. Both cameras 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

Sony A9 III		Sony A99
Mirrorless system camera		Digital single lens reflex
Sony E mount lenses		Sony A mount lenses
24 MP – Full Frame sensor		24 MP – Full Frame sensor
4K/120p Video		1080/60p Video
ISO 250-25,600 (125 - 51,200)		ISO 100-25,600
Electronic viewfinder (9440k dots)		Electronic viewfinder (2359k dots)
3.2" LCD – 2100k dots		3.0" LCD – 1229k dots
Fully flexible touchscreen		Fully flexible screen (no touchscreen)
120 shutter flaps per second		6 shutter flaps per second
In-body stabilization		In-body stabilization
Weathersealed body		Weathersealed body
530 shots per battery charge		500 shots per battery charge
136 x 97 x 83 mm, 702 g		147 x 111 x 78 mm, 812 g

Check A9 III 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 A9 III 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 A9 III and the Sony A99. 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 A99 is notably larger (24 percent) than the Sony A9 III. Moreover, the A99 is markedly heavier (16 percent) than the A9 III. 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 A9 III gets 530 shots out of its Sony NP-FZ100 battery, while the A99 can take 500 images on a single charge of its Sony NP-FM500H power pack. The power pack in the A9 III can be charged via the USB port, so that it is not always necessary to take the battery charger along when travelling.

The table below summarizes the key physical specs of the two cameras alongside a broader set of comparators. 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.		Sony A9 III	136 mm	97 mm	83 mm	702 g	530	Y	Nov 2023	EUR 6 999	amazon.com
2.		Sony A99	147 mm	111 mm	78 mm	812 g	500	Y	Sep 2012	EUR 2 799	ebay.com
3.		Canon R6 Mark II	138 mm	98 mm	88 mm	670 g	450	Y	Nov 2022	EUR 2 899	amazon.com
4.		Fujifilm X-H2S	136 mm	93 mm	85 mm	660 g	580	Y	May 2022	EUR 2 749	amazon.com
5.		Panasonic S5 II	134 mm	102 mm	90 mm	740 g	370	Y	Jan 2023	EUR 2 199	amazon.com
6.		Sony A1	129 mm	97 mm	81 mm	737 g	530	Y	Jan 2021	EUR 7 299	amazon.com
7.		Sony A1 II	136 mm	97 mm	83 mm	743 g	520	Y	Nov 2024	EUR 7 499	amazon.com
8.		Sony A7 II	127 mm	96 mm	60 mm	599 g	350	Y	Nov 2014	EUR 2 099	ebay.com
9.		Sony A7 III	127 mm	96 mm	74 mm	650 g	610	Y	Feb 2018	EUR 2 299	amazon.com
10.		Sony A7R V	131 mm	97 mm	82 mm	723 g	530	Y	Oct 2022	EUR 4 499	amazon.com
11.		Sony A9	127 mm	96 mm	63 mm	673 g	650	Y	Apr 2017	EUR 5 299	ebay.com
12.		Sony A9 II	129 mm	96 mm	76 mm	678 g	690	Y	Oct 2019	EUR 5 399	amazon.com
13.		Sony A77	143 mm	104 mm	81 mm	732 g	470	Y	Aug 2011	EUR 1 299	ebay.com
14.		Sony A99 II	143 mm	104 mm	76 mm	849 g	490	Y	Sep 2016	EUR 3 599	ebay.com
15.		Sony A850	156 mm	117 mm	82 mm	895 g	880	Y	Aug 2009	EUR 1 999	ebay.com
16.		Sony A900	156 mm	117 mm	82 mm	895 g	880	Y	Sep 2008	EUR 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 manufacturer’s suggested retail prices give an idea on the placement of the camera in the maker’s lineup and the broader market. The A99 was launched at a markedly lower price (by 53 percent) than the A9 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.

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. 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.

Both cameras under consideration feature a full frame sensor, but their sensors differ slightly in size. The sensor area in the A99 is 1 percent bigger. 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.

In terms of chip-set technology, the A9 III uses a more advanced image processing engine (Dual BIONZ XR) than the A99 (BIONZ X), with benefits for noise reduction, color accuracy, and processing speed.

Even though the A99 has a slightly larger sensor, both cameras offer the same resolution of 24 megapixels. This implies that the A99 has a lower pixel density and marginally larger individual pixels (with a pixel pitch of 5.96μm 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 11 years and 1 month) 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 A9 III has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

The Sony Alpha A9 III has a native sensitivity range from ISO 250 to ISO 25600, which can be extended to ISO 125-51200. 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.

In terms of underlying technology, the A9 III is build around a Stacked CMOS sensor, while the A99 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.

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 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 A9 III	Full Frame	24.0	6000	4000	4K/120p	25.4	14.7	3243	96
2.		Sony A99	Full Frame	24.0	6000	4000	1080/60p	25.0	14.0	1555	89
3.		Canon R6 Mark II	Full Frame	24.0	6000	4000	4k/60p	25.4	14.6	3154	96
4.		Fujifilm X-H2S	APS-C	26.0	6240	4160	6.2k/30p	24.3	13.9	2224	86
5.		Panasonic S5 II	Full Frame	24.0	6000	4000	6K/30p	25.4	14.6	3158	96
6.		Sony A1	Full Frame	49.8	8640	5760	8k/30p	25.9	14.5	3163	98
7.		Sony A1 II	Full Frame	49.8	8640	5760	8k/30p	25.4	14.8	3363	97
8.		Sony A7 II	Full Frame	24.0	6000	4000	1080/60p	24.9	13.6	2449	90
9.		Sony A7 III	Full Frame	24.0	6000	4000	4K/30p	25.0	14.7	3730	96
10.		Sony A7R V	Full Frame	60.2	9504	6336	8k/24p	26.5	14.8	3187	100
11.		Sony A9	Full Frame	24.0	6000	4000	4K/30p	24.9	13.3	3517	92
12.		Sony A9 II	Full Frame	24.0	6000	4000	4K/30p	25.0	14.0	3434	93
13.		Sony A77	APS-C	24.0	6000	4000	1080/60p	24.0	13.2	801	78
14.		Sony A99 II	Full Frame	42.2	7952	5304	4K/30p	25.4	13.4	2317	92
15.		Sony A850	Full Frame	24.4	6048	4032	none	23.8	12.2	1415	79
16.		Sony A900	Full Frame	24.4	6048	4032	none	23.7	12.3	1431	79
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 also of capturing video footage. The two cameras under consideration both have sensors whose read-out speed is fast enough to capture moving pictures, but the A9 III provides a higher video resolution than the A99. It can shoot video footage at 4K/120p, while the A99 is limited to 1080/60p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a range of features. The two cameras under consideration 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 A99 (9440k vs 2359k dots). The table below summarizes some of the other core capabilities of the Sony A9 III 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 A9 III	9440	n	3.2 / 2100	full-flex	Y	1/80000s	120.0/s	n	Y
2.		Sony A99	2359	Y	3.0 / 1229	full-flex	n	1/8000s	6.0/s	n	Y
3.		Canon R6 Mark II	3690	n	3.0 / 1620	swivel	Y	1/8000s	12.0/s	n	Y
4.		Fujifilm X-H2S	5760	Y	3.0 / 1620	swivel	Y	1/8000s	15.0/s	n	Y
5.		Panasonic S5 II	3680	n	3.0 / 1840	swivel	Y	1/8000s	9.0/s	n	Y
6.		Sony A1	9437	n	3.0 / 1440	tilting	Y	1/8000s	30.0/s	n	Y
7.		Sony A1 II	9437	n	3.2 / 2100	full-flex	Y	1/8000s	30.0/s	n	Y
8.		Sony A7 II	2400	n	3.0 / 1230	tilting	n	1/8000s	5.0/s	n	Y
9.		Sony A7 III	2359	n	3.0 / 922	tilting	Y	1/8000s	10.0/s	n	Y
10.		Sony A7R V	9440	n	3.2 / 2100	full-flex	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 A9 II	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
13.		Sony A77	2359	Y	3.0 / 921	full-flex	n	1/8000s	12.0/s	Y	Y
14.		Sony A99 II	2400	Y	3.0 / 1229	full-flex	n	1/8000s	12.0/s	n	Y
15.		Sony A850	optical	Y	3.0 / 922	fixed	n	1/8000s	3.0/s	n	Y
16.		Sony A900	optical	Y	3.0 / 922	fixed	n	1/8000s	5.0/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 III has a touchscreen, while the A99 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, the A9 III 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).

The Sony A9 III 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 A9 III writes its imaging data to CFexpress (type A) or SDXC cards, while the A99 uses SDXC or Memory Stick PRO Duo cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails. The A9 III supports UHS-II cards (Ultra High Speed data transfer of up to 312 MB/s), while the A99 can use UHS-I cards (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 A9 III 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 A9 III	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
2.		Sony A99	Y	stereo / mono	Y	Y	mini	2.0	-	-	-
3.		Canon R6 Mark II	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
4.		Fujifilm X-H2S	Y	stereo / mono	Y	Y	full	3.0	Y	-	Y
5.		Panasonic S5 II	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
6.		Sony A1	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
7.		Sony A1 II	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
8.		Sony A7 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
9.		Sony A7 III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
10.		Sony A7R V	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 A9 II	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
13.		Sony A77	Y	stereo / mono	Y	-	mini	2.0	-	-	-
14.		Sony A99 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	Y
15.		Sony A850	Y	- / -	-	-	mini	2.0	-	-	-
16.		Sony A900	Y	- / -	-	-	mini	2.0	-	-	-

It is notable that the A9 III offers wifi support, while the A99 does not. Wifi can be a very convenient means to transfer image data to an off-camera location.

Both cameras feature a PC Sync terminal to control professional strobe lights, which will be appreciated by studio photographers.

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 A9 III 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 A9 III and A99 can be found, respectively, in the Sony A9 III Manual (free pdf) or the online Sony A99 Manual.

Review summary

So what is the bottom line? Which of the two cameras – the Sony A9 III or the Sony A99 – has the upper hand? Is one clearly better than the other? The listing below highlights the relative strengths of the two models.

Advantages of the Sony Alpha A9 III:

• Better jpgs: Has a more modern image processing engine (Dual BIONZ XR vs BIONZ X).
• Better video: Provides higher definition movie capture (4K/120p vs 1080/60p).
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• More detailed viewfinder: Has higher resolution electronic viewfinder (9440k vs 2359k dots).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.9x vs 0.71x).
• Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
• More detailed LCD: Has a higher resolution rear screen (2100k vs 1229k dots).
• Fewer buttons to press: Is equipped with a touch-sensitive rear screen to facilitate handling.
• Faster shutter: Has higher mechanical shutter speed (1/80000s vs 1/8000s) to freeze action.
• Faster burst: Shoots at higher frequency (120 vs 6 flaps/sec) to capture the decisive moment.
• Less disturbing: Has an electronic shutter option for completely silent shooting.
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• More compact: Is smaller (136x97mm vs 147x111mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 110g or 14 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.
• Faster data transfer: Supports a more advanced USB protocol (3.2 vs 2.0).
• Easier file upload: Has wifi built in for automatic backup or image transfer to the web.
• Easier wireless transfer: Supports Bluetooth for image sharing without cables.
• Faster buffer clearing: Supports a more advanced SD data transfer standard (UHS-II vs UHS-I).
• More modern: Reflects 11 years and 1 month of technical progress since the A99 launch.

Reasons to prefer the Sony Alpha SLT-A99:

• Easier setting verification: Features a control panel on top to check shooting parameters.
• Easier geotagging: Features an internal GPS sensor to log localization data.
• More affordable: Was introduced into a lower priced category (53 percent cheaper at launch).
• More heavily discounted: Has been around for much longer (launched in September 2012).

If the number of relative strengths (bullet points above) is taken as a guide, the A9 III is the clear winner of the match-up (22 : 4 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 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 A9 III 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 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 III 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 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	Street Price
1.		Sony A9 III	4.5/5	..	..	91/100	..	..	Nov 2023	EUR 6 999	amazon.com
2.		Sony A99	5/5	..	..	84/100	4.5/5	4.5/5	Sep 2012	EUR 2 799	ebay.com
3.		Canon R6 Mark II	5/5	+ +	4.5/5	91/100	4.5/5	5/5	Nov 2022	EUR 2 899	amazon.com
4.		Fujifilm X-H2S	5/5	+	5/5	90/100	5/5	5/5	May 2022	EUR 2 749	amazon.com
5.		Panasonic S5 II	4.5/5	+ +	5/5	90/100	4.5/5	5/5	Jan 2023	EUR 2 199	amazon.com
6.		Sony A1	5/5	o	4.5/5	93/100	4.5/5	5/5	Jan 2021	EUR 7 299	amazon.com
7.		Sony A1 II	..	..	..	..	..	..	Nov 2024	EUR 7 499	amazon.com
8.		Sony A7 II	5/5	+	4/5	82/100	4.5/5	5/5	Nov 2014	EUR 2 099	ebay.com
9.		Sony A7 III	..	+ +	4.5/5	89/100	5/5	5/5	Feb 2018	EUR 2 299	amazon.com
10.		Sony A7R V	5/5	+ +	4.5/5	92/100	..	..	Oct 2022	EUR 4 499	amazon.com
11.		Sony A9	5/5	+ +	4.8/5	89/100	5/5	5/5	Apr 2017	EUR 5 299	ebay.com
12.		Sony A9 II	..	..	5/5	90/100	5/5	5/5	Oct 2019	EUR 5 399	amazon.com
13.		Sony A77	5/5	91/100	..	81/100	..	5/5	Aug 2011	EUR 1 299	ebay.com
14.		Sony A99 II	..	..	4.5/5	85/100	4.5/5	4.5/5	Sep 2016	EUR 3 599	ebay.com
15.		Sony A850	3/5	..	..	75/100	..	4.5/5	Aug 2009	EUR 1 999	ebay.com
16.		Sony A900	..	+ +	..	+ +	4.5/5	5/5	Sep 2008	EUR 2 799	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The above review scores should be interpreted with care, though. The ratings are only valid when referring to cameras in the same category and of the same age. 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.

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Other camera comparisons

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