Sony A77 vs A9 III

The Sony Alpha SLT-A77 and the Sony Alpha A9 III are two digital cameras that were officially introduced, respectively, in August 2011 and November 2023. The A77 is a DSLR, while the A9 III is a mirrorless interchangeable lens camera. The cameras are based on an APS-C (A77) and a full frame (A9 III) 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 A77		Sony A9 III
Digital single lens reflex		Mirrorless system camera
Sony A mount lenses		Sony E mount lenses
24 MP – APS-C sensor		24 MP – Full Frame sensor
1080/60p Video		4K/120p Video
ISO 100-16,000 (50 - 25,600)		ISO 250-25,600 (125 - 51,200)
Electronic viewfinder (2359k dots)		Electronic viewfinder (9440k dots)
3.0" LCD – 921k dots		3.2" LCD – 2100k dots
Fully flexible screen (no touchscreen)		Fully flexible touchscreen
12 shutter flaps per second		120 shutter flaps per second
In-body stabilization		In-body stabilization
Weathersealed body		Weathersealed body
470 shots per battery charge		530 shots per battery charge
143 x 104 x 81 mm, 732 g		136 x 97 x 83 mm, 702 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Sony Alpha SLT-A77 and the Sony Alpha A9 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 A77 and the Sony A9 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 size 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 A9 III is notably smaller (11 percent) than the Sony A77. Moreover, the A9 III is slightly lighter (4 percent) than the A77. 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 A77 gets 470 shots out of its Sony NP-FM500H battery, while the A9 III can take 530 images on a single charge of its Sony NP-FZ100 power pack. The power pack in the A9 III can be charged via the USB port, 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. 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	Street Price
1.		Sony A77	143 mm	104 mm	81 mm	732 g	470	Y	Aug 2011	EUR 1 299	ebay.com
2.		Sony A9 III	136 mm	97 mm	83 mm	702 g	530	Y	Nov 2023	EUR 6 999	amazon.com
3.		Canon 6D	145 mm	111 mm	71 mm	770 g	1090	Y	Sep 2012	EUR 1 999	ebay.com
4.		Nikon D600	141 mm	113 mm	82 mm	850 g	900	Y	Sep 2012	EUR 2 149	ebay.com
5.		Nikon Z6	134 mm	101 mm	67 mm	675 g	310	Y	Aug 2018	EUR 2 449	ebay.com
6.		Panasonic GH5	139 mm	98 mm	87 mm	725 g	410	Y	Jan 2017	EUR 1 999	ebay.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 A9	127 mm	96 mm	63 mm	673 g	650	Y	Apr 2017	EUR 5 299	ebay.com
11.		Sony A9 II	129 mm	96 mm	76 mm	678 g	690	Y	Oct 2019	EUR 5 399	amazon.com
12.		Sony A77 II	143 mm	104 mm	81 mm	647 g	480	Y	May 2014	EUR 1 199	ebay.com
13.		Sony A99	147 mm	111 mm	78 mm	812 g	500	Y	Sep 2012	EUR 2 799	ebay.com
14.		Sony A850	156 mm	117 mm	82 mm	895 g	880	Y	Aug 2009	EUR 1 999	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 listed launch prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The A77 was launched at a markedly lower price (by 77 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. 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. 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 tend to be associated with larger, more expensive camera bodies and lenses.

Of the two cameras under consideration, the Sony A77 features an APS-C sensor and the Sony A9 III a full frame sensor. The sensor area in the A9 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 A9 III uses a more advanced image processing engine (Dual BIONZ XR) than the A77 (BIONZ X), with benefits for noise reduction, color accuracy, and processing speed.

Even though the A9 III has a larger sensor, both cameras offer the same resolution of 24 megapixels. This implies that the A9 III has a lower pixel density and larger individual pixels (with a pixel pitch of 5.94μm versus 3.91μm for the A77), which gives it a potential advantage in terms of light gathering capacity. In addition, the A9 III is much more recent (by 12 years and 2 months) than the A77, and its sensor will have benefitted from technological advances during this time.

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 SLT-A77 has a native sensitivity range from ISO 100 to ISO 16000, which can be extended to ISO 50-25600. The corresponding ISO settings for the Sony Alpha A9 III are ISO 250 to ISO 25600, with the possibility to increase the ISO range to 125-51200.

In terms of underlying technology, the A77 is build around a CMOS sensor, while the A9 III uses a Stacked 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. 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 A77	APS-C	24.0	6000	4000	1080/60p	24.0	13.2	801	78
2.		Sony A9 III	Full Frame	24.0	6000	4000	4K/120p	25.4	14.7	3243	96
3.		Canon 6D	Full Frame	20.0	5472	3648	1080/30p	23.8	12.1	2340	82
4.		Nikon D600	Full Frame	24.2	6016	4016	1080/30p	25.1	14.2	2980	94
5.		Nikon Z6	Full Frame	24.3	6048	4024	4K/30p	25.3	14.3	3299	95
6.		Panasonic GH5	Four Thirds	20.2	5184	3888	4K/60p	23.9	13.0	807	77
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 A9	Full Frame	24.0	6000	4000	4K/30p	24.9	13.3	3517	92
11.		Sony A9 II	Full Frame	24.0	6000	4000	4K/30p	25.0	14.0	3434	93
12.		Sony A77 II	APS-C	24.0	6000	4000	1080/60p	24.4	13.4	1013	82
13.		Sony A99	Full Frame	24.0	6000	4000	1080/60p	25.0	14.0	1555	89
14.		Sony A850	Full Frame	24.4	6048	4032	none	23.8	12.2	1415	79
Note: DXO values in italics represent estimates based on sensor size and age.

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, but the A9 III provides a better video resolution than the A77. It can shoot movie footage at 4K/120p, while the A77 is limited to 1080/60p.

Feature comparison

Beyond 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 III offers a substantially higher resolution than the one in the A77 (9440k vs 2359k dots). The table below summarizes some of the other core capabilities of the Sony A77 and Sony A9 III 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 A77	2359	Y	3.0 / 921	full-flex	n	1/8000s	12.0/s	Y	Y
2.		Sony A9 III	9440	n	3.2 / 2100	full-flex	Y	1/80000s	120.0/s	n	Y
3.		Canon 6D	optical	Y	3.0 / 1040	fixed	n	1/4000s	4.5/s	n	n
4.		Nikon D600	optical	Y	3.0 / 921	fixed	n	1/4000s	5.5/s	Y	n
5.		Nikon Z6	3690	Y	3.2 / 2100	tilting	Y	1/8000s	12.0/s	n	Y
6.		Panasonic GH5	3680	n	3.2 / 1620	swivel	Y	1/8000s	12.0/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 A9	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
11.		Sony A9 II	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
12.		Sony A77 II	2359	Y	3.0 / 1229	full-flex	n	1/8000s	12.0/s	Y	Y
13.		Sony A99	2359	Y	3.0 / 1229	full-flex	n	1/8000s	6.0/s	n	Y
14.		Sony A850	optical	Y	3.0 / 922	fixed	n	1/8000s	3.0/s	n	Y
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 A77 has one, while the A9 III does not. While the built-in flash of the A77 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 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 A77 writes its imaging data to SDXC or Memory Stick PRO Duo cards, while the A9 III uses CFexpress (type A) or SDXC cards. The A9 III features dual card slots, which can be very useful in case a memory card fails. In contrast, the A77 only has one slot. The A9 III supports UHS-II cards (Ultra High Speed data transfer of up to 312 MB/s), while the A77 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 SLT-A77 and Sony Alpha A9 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 A77	Y	stereo / mono	Y	-	mini	2.0	-	-	-
2.		Sony A9 III	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
3.		Canon 6D	Y	mono / mono	Y	-	mini	2.0	Y	-	-
4.		Nikon D600	Y	mono / mono	Y	Y	mini	2.0	-	-	-
5.		Nikon Z6	Y	stereo / mono	Y	Y	micro	3.1	Y	-	Y
6.		Panasonic GH5	Y	stereo / mono	Y	Y	full	3.1	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 A9	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	Y
11.		Sony A9 II	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
12.		Sony A77 II	Y	stereo / mono	Y	-	mini	2.0	Y	Y	-
13.		Sony A99	Y	stereo / mono	Y	Y	mini	2.0	-	-	-
14.		Sony A850	Y	- / -	-	-	mini	2.0	-	-	-

It is notable that the A9 III offers wifi support, which can be a very convenient means to transfer image data to an off-camera location. In contrast, the A77 does not provide wifi capability.

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 A77 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 A77 has been discontinued (but can be found pre-owned on ebay). As a replacement in the same line of cameras, the A77 was succeeded by the Sony A77 II. Further information on the features and operation of the A77 and A9 III can be found, respectively, in the Sony A77 Manual (free pdf) or the online Sony A9 III Manual.

Review summary

So what is the bottom line? Which of the two cameras – the Sony A77 or the Sony A9 III – has the upper hand? Is one clearly better than the other? The listing below highlights the relative strengths of the two models.

Reasons to prefer the Sony Alpha SLT-A77:

• Easier setting verification: Features an LCD display on top to control shooting parameters.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• Easier geotagging: Features an internal GPS sensor to log localization data.
• More affordable: Was introduced into a lower priced category (77 percent cheaper at launch).
• More heavily discounted: Has been available for much longer (launched in August 2011).

Advantages of the Sony Alpha A9 III:

• Better image quality: Is equipped with a larger and more technologically advanced sensor.
• Richer colors: The sensor size advantage translates into images with better, more accurate colors.
• More dynamic range: Larger sensor captures a wider spectrum of light and dark details.
• Better low-light sensitivity: Larger sensor produces good images even in poorly lit environments.
• 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.
• 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 (0.9x vs 0.73x).
• 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 921k dots).
• Fewer buttons to press: Has a touchscreen to facilitate handling and shooting adjustments.
• Faster shutter: Has higher mechanical shutter speed (1/80000s vs 1/8000s) to freeze action.
• Faster burst: Shoots at higher frequency (120 vs 12 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 143x104mm) and will fit more readily into a bag.
• Longer lasting: Gets more shots (530 versus 470) out of a single battery charge.
• Easier travel charging: Can be conveniently charged via its USB port.
• More legacy lens friendly: Can use many 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.
• 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: Reflects 12 years and 2 months of technical progress since the A77 launch.

If the count of individual advantages (bullet points above) is taken as a guide, the A9 III is the clear winner of the contest (28 : 5 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 wildlife photographer will view the differences between cameras in a way that diverges from the perspective of a family photog, and a person interested in architecture has distinct needs from a sports 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 A77 and the Sony A9 III place the cameras among the top in their class? Find out in the latest Best DSLR Camera and Best Mirrorless Interchangeable Lens 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 remains incomplete and does no justice, for example, to the way the A77 or the A9 III perform in practice. 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 why expert reviews are important. 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 A77	5/5	91/100	..	81/100	..	5/5	Aug 2011	EUR 1 299	ebay.com
2.		Sony A9 III	4.5/5	..	..	91/100	..	..	Nov 2023	EUR 6 999	amazon.com
3.		Canon 6D	5/5	+ +	..	83/100	4.5/5	4.5/5	Sep 2012	EUR 1 999	ebay.com
4.		Nikon D600	4/5	+ +	..	87/100	5/5	4.5/5	Sep 2012	EUR 2 149	ebay.com
5.		Nikon Z6	5/5	..	5/5	89/100	4.5/5	5/5	Aug 2018	EUR 2 449	ebay.com
6.		Panasonic GH5	4.5/5	+ +	..	85/100	4.5/5	5/5	Jan 2017	EUR 1 999	ebay.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 A9	5/5	+ +	4.8/5	89/100	5/5	5/5	Apr 2017	EUR 5 299	ebay.com
11.		Sony A9 II	..	..	5/5	90/100	5/5	5/5	Oct 2019	EUR 5 399	amazon.com
12.		Sony A77 II	4/5	..	..	80/100	4.5/5	5/5	May 2014	EUR 1 199	ebay.com
13.		Sony A99	5/5	..	..	84/100	4.5/5	4.5/5	Sep 2012	EUR 2 799	ebay.com
14.		Sony A850	3/5	..	..	75/100	..	4.5/5	Aug 2009	EUR 1 999	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The review scores listed above should be treated with care, 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 rating-comparisons among cameras that span long time periods or concern very differently equipped models make little sense. It should also be noted that some of the review sites have over time altered the way they render their verdicts.

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Other camera comparisons

Did this review help to inform your camera decision process? In case you would like to check on the differences and similarities of other camera models, just make your choice using the following search menu. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored.

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