Sony A7R III vs A900

The Sony Alpha A7R III and the Sony Alpha A900 are two digital cameras that were revealed to the public, respectively, in October 2017 and September 2008. The A7R III is a mirrorless interchangeable lens camera, while the A900 is a DSLR. Both cameras are equipped with a full frame sensor. The A7R III has a resolution of 42.2 megapixels, whereas the A900 provides 24.4 MP.

Below is an overview of the main specs of the two cameras as a starting point for the comparison.

Headline Specifications

Sony A7R III		Sony A900
Mirrorless system camera		Digital single lens reflex
Sony E mount lenses		Sony A mount lenses
42.2 MP – Full Frame sensor		24.4 MP – Full Frame sensor
4K/30p Video		no Video
ISO 100-32,000 (50 - 102,400)		ISO 200-3,200 (100 - 6,400)
Electronic viewfinder (3686k dots)		Optical viewfinder
3.0" LCD – 1440k dots		3.0" LCD – 922k dots
Tilting touchscreen		Fixed screen (not touch-sensitive)
10 shutter flaps per second		5 shutter flaps per second
In-body stabilization		In-body stabilization
Weathersealed body		Weathersealed body
650 shots per battery charge		880 shots per battery charge
127 x 96 x 74 mm, 650 g		156 x 117 x 82 mm, 895 g

Check A7R III offers at
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Going beyond this snapshot of core features and characteristics, what are the differences between the Sony Alpha A7R III and the Sony Alpha A900? 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 A7R III and the Sony A900 is provided in the side-by-side display below. The two cameras are presented according to their relative size. Three successive views from the front, the top, and the rear are shown. 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 A900 is considerably larger (50 percent) than the Sony A7R III. Moreover, the A900 is substantially heavier (38 percent) than the A7R 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 A7R III gets 650 shots out of its NP-FZ100 battery, while the A900 can take 880 images on a single charge of its NP-FM500H power pack. The power pack in the A7R III can be charged via the USB port, so that it is not always necessary to take the battery charger along when travelling.

The following table provides a synthesis of the main physical specifications of the two cameras and other similar ones. 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 A7R III	127 mm	96 mm	74 mm	650 g	650	Y	Oct 2017	3,199	ebay.com
2.		Sony A900	156 mm	117 mm	82 mm	895 g	880	Y	Sep 2008	2,999	ebay.com
3.		Nikon Z7	134 mm	101 mm	67 mm	675 g	330	Y	Aug 2018	3,399	ebay.com
4.		Sony A1	129 mm	97 mm	81 mm	737 g	530	Y	Jan 2021	6,499	amazon.com
5.		Sony A7S III	127 mm	97 mm	81 mm	699 g	600	Y	Jul 2020	3,499	amazon.com
6.		Sony A9 II	129 mm	96 mm	76 mm	678 g	690	Y	Oct 2019	4,499	amazon.com
7.		Sony A7R IV	129 mm	96 mm	78 mm	665 g	670	Y	Jul 2019	3,499	amazon.com
8.		Sony A7 III	127 mm	96 mm	74 mm	650 g	610	Y	Feb 2018	1,999	amazon.com
9.		Sony A9	127 mm	96 mm	63 mm	673 g	650	Y	Apr 2017	4,499	ebay.com
10.		Sony A99 II	143 mm	104 mm	76 mm	849 g	490	Y	Sep 2016	3,199	ebay.com
11.		Sony A7R II	127 mm	96 mm	60 mm	625 g	290	Y	Jun 2015	3,199	ebay.com
12.		Sony A7S II	127 mm	96 mm	60 mm	627 g	370	Y	Sep 2015	2,999	ebay.com
13.		Sony A99	147 mm	111 mm	78 mm	812 g	500	Y	Sep 2012	2,799	ebay.com
14.		Sony A850	156 mm	117 mm	82 mm	895 g	880	Y	Aug 2009	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

The price is, of course, an important factor in any camera decision. The listed launch prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The A900 was somewhat cheaper (by 6 percent) than the A7R III at launch, but both cameras fall into the same price category. 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.

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. Further, a large sensor camera will give the photographer additional creative options when using shallow depth-of-field to isolate a subject from its background. On the downside, larger sensors tend to be associated with larger, more expensive camera bodies and lenses.

Both cameras under consideration feature a full frame sensor and have a format factor (sometimes also referred to as "crop factor") of 1.0. Within the spectrum of camera sensors, this places the review cameras among the large-sensor cameras that aim for top notch image quality. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

In terms of chip-set technology, the A7R III uses a more advanced image processing engine (BIONZ X) than the A900 (BIONZ), with benefits for noise reduction, color accuracy, and processing speed.

While the two cameras under review share the same sensor size, the A7R III offers a higher resolution of 42.2 megapixels, compared with 24.4 MP of the A900. This megapixels advantage translates into a 31 percent gain in linear resolution. On the other hand, these sensor specs imply that the A7R III has a higher pixel density and a smaller size of the individual pixel (with a pixel pitch of 4.52μm versus 5.94μm for the A900). In this context, it should be noted, however, that the A7R III is much more recent (by 9 years and 1 month) than the A900, and its sensor will have benefitted from technological advances during this time that compensate for the smaller pixel size. Coming back to sensor resolution, it should be mentioned that the A7R III has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

The resolution advantage of the Sony A7R III implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A7R III for good quality output (200 dots per inch) amounts to 39.8 x 26.5 inches or 101 x 67.4 cm, for very good quality (250 dpi) 31.8 x 21.2 inches or 80.8 x 53.9 cm, and for excellent quality (300 dpi) 26.5 x 17.7 inches or 67.3 x 44.9 cm. The corresponding values for the Sony A900 are 30.2 x 20.2 inches or 76.8 x 51.2 cm for good quality, 24.2 x 16.1 inches or 61.4 x 41 cm for very good quality, and 20.2 x 13.4 inches or 51.2 x 34.1 cm for excellent quality prints.

The A7R III has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

Unlike the A900, the A7R III has the capacity to capture high quality composite images by combining multiple shots after shifting its sensor by miniscule distances. This multi-shot, pixel-shift mode is most suitable for photography of stationary objects (landscapes, studio scenes).

The Sony Alpha A7R III has a native sensitivity range from ISO 100 to ISO 32000, which can be extended to ISO 50-102400. The corresponding ISO settings for the Sony Alpha A900 are ISO 200 to ISO 3200, with the possibility to increase the ISO range to 100-6400.

In terms of underlying technology, the A7R III is build around a BSI-CMOS sensor, while the A900 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.

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 review, the A7R III provides substantially higher image quality than the A900, with an overall score that is 21 points higher. This advantage is based on 2.3 bits higher color depth, 2.4 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 A7R III	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
2.		Sony A900	Full Frame	24.4	6048	4032	none	23.7	12.3	1431	79
3.		Nikon Z7	Full Frame	45.4	8256	5504	4K/30p	26.3	14.6	2668	99
4.		Sony A1	Full Frame	49.8	8640	5760	8k/30p	25.9	14.5	3163	98
5.		Sony A7S III	Full Frame	12.0	4240	2832	4K/120p	23.7	13.9	2520	86
6.		Sony A9 II	Full Frame	24.0	6000	4000	4K/30p	25.0	14.0	3434	93
7.		Sony A7R IV	Full Frame	60.2	9504	6336	4K/30p	26.0	14.8	3344	99
8.		Sony A7 III	Full Frame	24.0	6000	4000	4K/30p	25.0	14.7	3730	96
9.		Sony A9	Full Frame	24.0	6000	4000	4K/30p	24.9	13.3	3517	92
10.		Sony A99 II	Full Frame	42.2	7952	5304	4K/30p	25.4	13.4	2317	92
11.		Sony A7R II	Full Frame	42.2	7952	5304	4K/30p	26.0	13.9	3434	98
12.		Sony A7S II	Full Frame	12.0	4240	2832	4K/30p	23.6	13.3	2993	85
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

Many modern cameras are not only capable of taking still images, but also of capturing video footage. The A7R III indeed provides movie recording capabilities, while the A900 does not. The highest resolution format that the A7R III can use is 4K/30p.

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. For example, the A7R III has an electronic viewfinder (3686k dots), while the A900 has an optical one. Both systems have their advantages, with the electronic viewfinder making it possible to project supplementary shooting information into the framing view, whereas the optical viewfinder offers lag-free viewing and a very clear framing image. The viewfinders of both cameras offer the same field of view (100%), but the viewfinder of the A7R III has a higher magnification than the one of the A900 (0.78x vs 0.74x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The adjacent table lists some of the other core features of the Sony A7R III and Sony A900 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 A7R III	3686	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
2.		Sony A900	optical	Y	3.0 / 922	fixed	n	1/8000s	5.0/s	n	Y
3.		Nikon Z7	3690	Y	3.2 / 2100	tilting	Y	1/8000s	9.0/s	n	Y
4.		Sony A1	9437	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
5.		Sony A7S III	9440	n	3.0 / 1440	swivel	Y	1/8000s	10.0/s	n	Y
6.		Sony A9 II	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
7.		Sony A7R IV	5760	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
8.		Sony A7 III	2359	n	3.0 / 922	tilting	Y	1/8000s	10.0/s	n	Y
9.		Sony A9	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
10.		Sony A99 II	2400	Y	3.0 / 1229	full-flex	n	1/8000s	12.0/s	n	Y
11.		Sony A7R II	2400	n	3.0 / 1229	tilting	n	1/8000s	5.0/s	n	Y
12.		Sony A7S II	2400	n	3.0 / 1229	tilting	n	1/8000s	5.0/s	n	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
Notes: *) 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 A7R III has a touchscreen, while the A900 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 A7R 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 A7R 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 A7R III writes its imaging data to SDXC or Memory Stick PRO Duo cards, while the A900 uses Compact Flash or Memory Stick PRO Duo cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails.

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 A7R III and Sony Alpha A900 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 A7R III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
2.		Sony A900	Y	- / -	-	-	mini	2.0	-	-	-
3.		Nikon Z7	Y	stereo / mono	Y	Y	micro	3.1	Y	-	Y
4.		Sony A1	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
5.		Sony A7S III	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
6.		Sony A9 II	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
7.		Sony A7R IV	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
8.		Sony A7 III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
9.		Sony A9	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	Y
10.		Sony A99 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	Y
11.		Sony A7R II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
12.		Sony A7S II	Y	stereo / mono	Y	Y	micro	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 A7R III offers wifi support, while the A900 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.

Both the A7R III and the A900 have been discontinued, but can regularly be found used on ebay. The A900 was replaced by the Sony A99, while the A7R III was followed by the Sony A7R IV. Further information on the features and operation of the A7R III and A900 can be found, respectively, in the Sony A7R III Manual (free pdf) or the online Sony A900 Manual.

Review summary

So what is the bottom line? Is the Sony A7R III better than the Sony A900 or vice versa? A synthesis of the relative strong points of each of the models is listed below.

Arguments in favor of the Sony Alpha A7R III:

• More detail: Offers more megapixels (42.2 vs 24.4MP) with a 32% higher linear resolution.
• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• High quality composites: Can combine several shots after pixel-shifting its sensor.
• Better image quality: Scores substantially higher (21 points) in the DXO overall assessment.
• Richer colors: Generates images with noticeably better colors (2.3 bits more color depth).
• More dynamic range: Captures a larger spectrum of light and dark details (2.4 EV of extra DR).
• Better low-light sensitivity: Requires less light for good images (1.3 stops ISO advantage).
• Better jpgs: Has a more modern image processing engine (BIONZ X vs BIONZ).
• Broader imaging potential: Can record not only still images but also 4K/30p movies.
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• More framing info: Has an electronic viewfinder that displays shooting data.
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.78x vs 0.74x).
• More detailed LCD: Has a higher resolution rear screen (1440k vs 922k dots).
• More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
• Fewer buttons to press: Is equipped with a touch-sensitive rear screen to facilitate handling.
• Faster burst: Shoots at higher frequency (10 vs 5 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 (127x96mm vs 156x117mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 245g or 27 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 (3.1 vs 2.0).
• 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 modern: Reflects 9 years and 1 month of technical progress since the A900 launch.

Advantages of the Sony Alpha A900:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Brighter framing: Features an optical viewfinder for clear, lag-free composition.
• Easier setting verification: Features a control panel on top to check shooting parameters.
• Longer lasting: Gets more shots (880 versus 650) out of a single battery charge.
• More heavily discounted: Has been around for much longer (launched in September 2008).

If the count of relative strengths (bullet points above) is taken as a measure, the A7R III is the clear winner of the match-up (27 : 5 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 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 A7R III and the Sony A900 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 remains incomplete and does no justice, for example, to the way the A7R III or the A900 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 hands-on reviews by experts 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 (USD)	Street Price
1.		Sony A7R III	..	+ +	4/5	90/100	4.5/5	5/5	Oct 2017	3,199	ebay.com
2.		Sony A900	..	+ +	..	+ +	4.5/5	5/5	Sep 2008	2,999	ebay.com
3.		Nikon Z7	5/5	+	4.8/5	89/100	4.5/5	5/5	Aug 2018	3,399	ebay.com
4.		Sony A1	5/5	o	4.5/5	93/100	4.5/5	5/5	Jan 2021	6,499	amazon.com
5.		Sony A7S III	..	+ +	5/5	91/100	4.5/5	5/5	Jul 2020	3,499	amazon.com
6.		Sony A9 II	..	..	5/5	90/100	5/5	5/5	Oct 2019	4,499	amazon.com
7.		Sony A7R IV	5/5	+	4.5/5	91/100	4.5/5	5/5	Jul 2019	3,499	amazon.com
8.		Sony A7 III	..	+ +	4.5/5	89/100	5/5	5/5	Feb 2018	1,999	amazon.com
9.		Sony A9	5/5	+ +	4.8/5	89/100	5/5	5/5	Apr 2017	4,499	ebay.com
10.		Sony A99 II	..	..	4.5/5	85/100	4.5/5	4.5/5	Sep 2016	3,199	ebay.com
11.		Sony A7R II	5/5	+ +	5/5	90/100	5/5	5/5	Jun 2015	3,199	ebay.com
12.		Sony A7S II	5/5	+	..	..	4.5/5	5/5	Sep 2015	2,999	ebay.com
13.		Sony A99	5/5	..	..	84/100	4.5/5	4.5/5	Sep 2012	2,799	ebay.com
14.		Sony A850	3/5	..	..	75/100	..	4.5/5	Aug 2009	1,999	ebay.com
Notes: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

Care should be taken when interpreting the review scores above, 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. 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

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