Canon G3 X vs Sony A99

The Canon PowerShot G3 X and the Sony Alpha SLT-A99 are two digital cameras that were officially introduced, respectively, in June 2015 and September 2012. The G3X is a fixed lens compact, while the A99 is a DSLR. The cameras are based on an one-inch (G3X) and a full frame (A99) sensor. The Canon has a resolution of 20 megapixels, whereas the Sony provides 24 MP.

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

Headline Specifications

Canon G3 X		Sony A99
Fixed lens compact camera		Digital single lens reflex
24-600mm f/2.8-5.6		Sony A mount lenses
20 MP – 1" sensor		24 MP – Full Frame sensor
1080/60p Video		1080/60p Video
ISO 125-12,800 (125 - 25,600)		ISO 100-25,600
Viewfinder optional		Electronic viewfinder (2359k dots)
3.2" LCD – 1620k dots		3.0" LCD – 1229k dots
Tilting touchscreen		Fully flexible screen (no touchscreen)
5.9 shutter flaps per second		6 shutter flaps per second
Lens-based stabilization		In-body stabilization
Weathersealed body		Weathersealed body
300 shots per battery charge		500 shots per battery charge
123 x 77 x 105 mm, 733 g		147 x 111 x 78 mm, 812 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Canon PowerShot G3 X 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

An illustration of the physical size and weight of the Canon G3 X and the Sony A99 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 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 (72 percent) than the Canon G3 X. 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 and possibly misleading, as the G3X has a lens built in, whereas the A99 is an interchangeable lens camera that requires a separate lens. Attaching the latter will add extra weight and bulk to the setup.

Concerning battery life, the G3X gets 300 shots out of its NB-10L battery, while the A99 can take 500 images on a single charge of its NP-FM500H power pack.

The table below summarizes the key physical specs of the two cameras alongside a broader set of comparators. 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.		Canon G3 X	123 mm	77 mm	105 mm	733 g	300	Y	Jun 2015	999	ebay.com
2.		Sony A99	147 mm	111 mm	78 mm	812 g	500	Y	Sep 2012	2,799	ebay.com
3.		Canon 80D	139 mm	105 mm	79 mm	730 g	960	Y	Feb 2016	1,199	ebay.com
4.		Canon G9 X	98 mm	58 mm	31 mm	209 g	220	n	Oct 2015	529	ebay.com
5.		Canon G7 X	103 mm	60 mm	40 mm	304 g	210	n	Sep 2014	699	ebay.com
6.		Canon 70D	139 mm	104 mm	79 mm	755 g	920	Y	Jul 2013	1,199	ebay.com
7.		Panasonic FZ2500	138 mm	102 mm	135 mm	915 g	350	n	Sep 2016	1,199	amazon.com
8.		Panasonic FZ1000	137 mm	99 mm	131 mm	831 g	360	n	Jun 2014	899	ebay.com
9.		Sony A9 II	129 mm	96 mm	76 mm	678 g	690	Y	Oct 2019	4,499	amazon.com
10.		Sony A99 II	143 mm	104 mm	76 mm	849 g	490	Y	Sep 2016	3,199	ebay.com
11.		Sony RX10 III	133 mm	94 mm	127 mm	1051 g	420	Y	Mar 2016	1,499	ebay.com
12.		Sony RX100 V	102 mm	58 mm	41 mm	299 g	220	n	Oct 2016	999	ebay.com
13.		Sony RX10 II	129 mm	88 mm	102 mm	813 g	400	Y	Jun 2015	1,299	ebay.com
14.		Sony RX10	129 mm	88 mm	102 mm	813 g	420	Y	Oct 2013	1,299	ebay.com
15.		Sony A77	143 mm	104 mm	81 mm	732 g	470	Y	Aug 2011	1,399	ebay.com
16.		Sony A850	156 mm	117 mm	82 mm	895 g	880	Y	Aug 2009	1,999	ebay.com
17.		Sony A900	156 mm	117 mm	82 mm	895 g	880	Y	Sep 2008	2,999	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 G3X was launched at a lower price than the A99, despite having a lens built in. 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 imaging sensor is a crucial determinant 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 more expensive and lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Canon G3 X features an one-inch sensor and the Sony A99 a full frame sensor. The sensor area in the A99 is 634 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 2.7 and 1.0. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

With 24MP, the A99 offers a higher resolution than the G3X (20MP), but the A99 nevertheless has larger individual pixels (pixel pitch of 5.96μm versus 2.41μm for the G3X) due to its larger sensor. However, the G3X is a much more recent model (by 2 years and 9 months) than the A99, and its sensor will have benefitted from technological advances during this time that enhance the light gathering capacity of its pixel-units.

The resolution advantage of the Sony A99 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A99 for good quality output (200 dots per inch) amounts to 30 x 20 inches or 76.2 x 50.8 cm, for very good quality (250 dpi) 24 x 16 inches or 61 x 40.6 cm, and for excellent quality (300 dpi) 20 x 13.3 inches or 50.8 x 33.9 cm. The corresponding values for the Canon G3 X are 27.4 x 18.2 inches or 69.5 x 46.3 cm for good quality, 21.9 x 14.6 inches or 55.6 x 37.1 cm for very good quality, and 18.2 x 12.2 inches or 46.3 x 30.9 cm for excellent quality prints.

The Canon PowerShot G3 X has a native sensitivity range from ISO 125 to ISO 12800, which can be extended to ISO 125-25600. 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 G3X is build around a BSI-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.

For many cameras, data on sensor performance has been reported by DXO Mark. 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"). Of the two cameras under consideration, the A99 offers substantially better image quality than the G3X (overall score 26 points higher). The advantage is based on 3.6 bits higher color depth, 1.7 EV in additional dynamic range, and 1.6 stops in additional low light sensitivity. 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.		Canon G3 X	1-inch	20.0	5472	3648	1080/60p	21.4	12.3	521	63
2.		Sony A99	Full Frame	24.0	6000	4000	1080/60p	25.0	14.0	1555	89
3.		Canon 80D	APS-C	24.0	6000	4000	1080/60p	23.6	13.2	1135	79
4.		Canon G9 X	1-inch	20.0	5472	3648	1080/60p	21.5	12.3	495	63
5.		Canon G7 X	1-inch	20.0	5472	3648	1080/60p	23.0	12.7	556	71
6.		Canon 70D	APS-C	20.0	5472	3648	1080/30p	22.5	11.6	926	68
7.		Panasonic FZ2500	1-inch	20.0	5472	3648	4K/30p	23.0	12.6	538	70
8.		Panasonic FZ1000	1-inch	20.0	5472	3648	4K/30p	22.1	11.7	517	64
9.		Sony A9 II	Full Frame	24.0	6000	4000	4K/30p	25.0	14.0	3434	93
10.		Sony A99 II	Full Frame	42.2	7952	5304	4K/30p	25.4	13.4	2317	92
11.		Sony RX10 III	1-inch	20.0	5472	3648	4K/30p	23.1	12.6	472	70
12.		Sony RX100 V	1-inch	20.0	5472	3648	4K/30p	22.8	12.4	586	70
13.		Sony RX10 II	1-inch	20.0	5472	3648	4K/30p	23.0	12.6	531	70
14.		Sony RX10	1-inch	20.0	5472	3648	1080/60p	22.9	12.6	474	69
15.		Sony A77	APS-C	24.0	6000	4000	1080/60p	24.0	13.2	801	78
16.		Sony A850	Full Frame	24.4	6048	4032	none	23.8	12.2	1415	79
17.		Sony A900	Full Frame	24.4	6048	4032	none	23.7	12.3	1431	79

Many modern cameras are not only capable of taking still images, but can also record movies. Both cameras under consideration are equipped with sensors that have a sufficiently high read-out speed for moving images, and both provide the same movie specifications (1080/60p).

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. For example, the A99 has an electronic viewfinder (2359k dots), which can be very helpful when shooting in bright sunlight. In contrast, the G3X relies on live view and the rear LCD for framing. That said, the G3X can be equipped with an optional viewfinder – the EVF-DC1. The table below summarizes some of the other core capabilities of the Canon G3 X 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.		Canon G3 X	optional	n	3.2 / 1620	tilting	Y	1/2000s	5.9/s	Y	Y
2.		Sony A99	2359	Y	3.0 / 1229	full-flex	n	1/8000s	6.0/s	n	Y
3.		Canon 80D	optical	Y	3.0 / 1040	swivel	Y	1/8000s	7.0/s	Y	n
4.		Canon G9 X	none	n	3.0 / 1040	fixed	Y	1/2000s	6.0/s	Y	Y
5.		Canon G7 X	none	n	3.0 / 1040	tilting	Y	1/2000s	6.5/s	Y	Y
6.		Canon 70D	optical	Y	3.0 / 1040	swivel	Y	1/8000s	7.0/s	Y	n
7.		Panasonic FZ2500	2360	n	3.0 / 1040	swivel	Y	1/4000s	12.0/s	Y	Y
8.		Panasonic FZ1000	2359	n	3.0 / 921	swivel	n	1/4000s	12.0/s	Y	Y
9.		Sony A9 II	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 RX10 III	2359	Y	3.0 / 1229	tilting	n	1/2000s	14.0/s	Y	Y
12.		Sony RX100 V	2359	n	3.0 / 1229	tilting	n	1/2000s	24.0/s	Y	Y
13.		Sony RX10 II	2359	Y	3.0 / 1229	tilting	n	1/3200s	14.0/s	Y	Y
14.		Sony RX10	1440	Y	3.0 / 1229	tilting	n	1/3200s	10.0/s	Y	Y
15.		Sony A77	2359	Y	3.0 / 921	full-flex	n	1/8000s	12.0/s	Y	Y
16.		Sony A850	optical	Y	3.0 / 922	fixed	n	1/8000s	3.0/s	n	Y
17.		Sony A900	optical	Y	3.0 / 922	fixed	n	1/8000s	5.0/s	n	Y
Notes: *) 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 G3X has one, while the A99 does not. While the built-in flash of the G3X is not very powerful, it can at times be useful as a fill-in light.

The G3X writes its imaging data to SDXC cards, while the A99 uses 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 G3X 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 Canon PowerShot G3 X 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.		Canon G3 X	Y	stereo / mono	Y	Y	mini	2.0	Y	Y	-
2.		Sony A99	Y	stereo / mono	Y	Y	mini	2.0	-	-	-
3.		Canon 80D	Y	stereo / mono	Y	Y	mini	2.0	Y	Y	-
4.		Canon G9 X	-	stereo / mono	-	-	micro	2.0	Y	Y	-
5.		Canon G7 X	-	stereo / mono	-	-	micro	2.0	Y	Y	-
6.		Canon 70D	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
7.		Panasonic FZ2500	Y	stereo / mono	Y	Y	micro	2.0	Y	-	-
8.		Panasonic FZ1000	Y	stereo / mono	Y	-	micro	2.0	Y	Y	-
9.		Sony A9 II	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
10.		Sony A99 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	Y
11.		Sony RX10 III	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
12.		Sony RX100 V	-	stereo / mono	-	-	micro	2.0	Y	Y	-
13.		Sony RX10 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
14.		Sony RX10	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
15.		Sony A77	Y	stereo / mono	Y	-	mini	2.0	-	-	-
16.		Sony A850	Y	- / -	-	-	mini	2.0	-	-	-
17.		Sony A900	Y	- / -	-	-	mini	2.0	-	-	-

It is notable that the G3X 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 G3X) 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.

Both the G3X and the A99 have been discontinued, but can regularly be found used on ebay. The A99 was replaced by the Sony A99, while the G3X does not have a direct successor. Further information on the features and operation of the G3X and A99 can be found, respectively, in the Canon G3 X Manual (free pdf) or the online Sony A99 Manual.

Review summary

So what is the bottom line? Which of the two cameras – the Canon G3 X 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.

Reasons to prefer the Canon PowerShot G3 X:

• 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 (1620k vs 1229k dots).
• Fewer buttons to press: Is equipped with a touch-sensitive rear screen to facilitate handling.
• Ready to shoot: Comes with a built-in lens, while the A99 requires a separate lens.
• More compact: Is smaller (123x77mm vs 147x111mm) and thus needs less room in the bag.
• Less heavy: Is lighter even though it comes with a built-in lens (unlike the A99).
• 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.
• More affordable: Was introduced at a lower price, despite coming with a built-in lens.
• More modern: Reflects 2 years and 9 months of technical progress since the A99 launch.

Advantages of the Sony Alpha SLT-A99:

• More detail: Has more megapixels (24 vs 20MP), which boosts linear resolution by 10%.
• Better image quality: Scores substantially higher (26 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (3.6 bits more color depth).
• More dynamic range: Captures a broader range of light and dark details (1.7 EV of extra DR).
• Better low-light sensitivity: Can shoot in dim conditions (1.6 stops ISO advantage).
• Easier framing: Has an electronic viewfinder for image composition and settings control.
• Easier setting verification: Features a control panel on top to check shooting parameters.
• 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 1/2000s) to freeze action.
• More flexible: Makes it possible to change lenses and thus to use specialty optics.
• Longer lasting: Gets more shots (500 versus 300) out of a single battery charge.
• 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 number of relative strengths (bullet points above) is taken as a guide, the A99 is the clear winner of the contest (15 : 11 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 Canon G3 X and the Sony A99 place the cameras among the top in their class? Find out in the latest Best Superzoom 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 remains incomplete and does no justice, for example, to the way the G3X or the A99 perform in practice. User reviews, such as those found at amazon, can sometimes inform about these issues, but such feedback is often incomplete, inconsistent, and biased.

Expert reviews

This is why expert reviews 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.		Canon G3 X	3.5/5	+	..	..	4.5/5	4/5	Jun 2015	999	ebay.com
2.		Sony A99	5/5	..	..	84/100	4.5/5	4.5/5	Sep 2012	2,799	ebay.com
3.		Canon 80D	4/5	+ +	4.5/5	84/100	4.5/5	4.5/5	Feb 2016	1,199	ebay.com
4.		Canon G9 X	3.5/5	+ +	..	..	4.5/5	4.5/5	Oct 2015	529	ebay.com
5.		Canon G7 X	4/5	+ +	..	77/100	4.5/5	4.5/5	Sep 2014	699	ebay.com
6.		Canon 70D	5/5	+ +	..	83/100	4.5/5	5/5	Jul 2013	1,199	ebay.com
7.		Panasonic FZ2500	..	+	..	82/100	4.5/5	5/5	Sep 2016	1,199	amazon.com
8.		Panasonic FZ1000	4/5	+ +	..	82/100	4.5/5	4.5/5	Jun 2014	899	ebay.com
9.		Sony A9 II	..	..	5/5	90/100	5/5	5/5	Oct 2019	4,499	amazon.com
10.		Sony A99 II	..	..	4.5/5	85/100	4.5/5	4.5/5	Sep 2016	3,199	ebay.com
11.		Sony RX10 III	5/5	+	..	84/100	4.5/5	4.5/5	Mar 2016	1,499	ebay.com
12.		Sony RX100 V	4.5/5	+ +	..	83/100	4/5	4.5/5	Oct 2016	999	ebay.com
13.		Sony RX10 II	5/5	+ +	..	82/100	4.5/5	4/5	Jun 2015	1,299	ebay.com
14.		Sony RX10	5/5	+	..	80/100	4.5/5	4.5/5	Oct 2013	1,299	ebay.com
15.		Sony A77	5/5	91/100	..	81/100	..	5/5	Aug 2011	1,399	ebay.com
16.		Sony A850	3/5	..	..	75/100	..	4.5/5	Aug 2009	1,999	ebay.com
17.		Sony A900	..	+ +	..	+ +	4.5/5	5/5	Sep 2008	2,999	ebay.com
Notes: (+ +) 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. Hence, a score should always be seen in the context of the camera's market launch date and its price, 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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