Sony A9 vs A5100

The Sony Alpha A9 and the Sony Alpha A5100 are two digital cameras that were revealed to the public, respectively, in April 2017 and August 2014. Both the A9 and the A5100 are mirrorless interchangeable lens cameras that are based on a full frame (A9) and an APS-C (A5100) 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		Sony A5100
Mirrorless system camera		Mirrorless system camera
Sony E mount lenses		Sony E mount lenses
24 MP – Full Frame sensor		24 MP – APS-C sensor
4K/30p Video		1080/60p Video
ISO 100-51,200 (50 - 204,800)		ISO 100-25,600
Electronic viewfinder (3686k dots)		No viewfinder, LCD framing
3.0" LCD – 1440k dots		3.0" LCD – 922k dots
Tilting touchscreen		Tilting touchscreen
20 shutter flaps per second		6 shutter flaps per second
In-body stabilization		Lens stabilization only
Weathersealed body		not weather sealed
650 shots per battery charge		400 shots per battery charge
127 x 96 x 63 mm, 673 g		110 x 63 x 36 mm, 283 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Sony Alpha A9 and the Sony Alpha A5100? 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 A9 and the Sony A5100 is provided in the side-by-side display below. 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.

The A5100 can be obtained in two different colors (black, white), while the A9 is only available in black.

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Sony A5100 is considerably smaller (43 percent) than the Sony A9. Moreover, the A5100 is substantially lighter (58 percent) than the A9. It is worth mentioning in this context that the A9 is splash and dust resistant, while the A5100 does not feature any corresponding weather-sealing.

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. A larger imaging sensor will tend to go along with bigger and heavier lenses, although exceptions exist. You can compare the optics available for the two cameras in the Sony FE Lens Catalog (A9) and the Sony E-Mount Lens Catalog (A5100). Mirrorless cameras, such as the two under consideration, have the additional advantage of having a short flange to focal plane distance, which makes it possible to mount many lenses from other systems onto the camera via adapters.

Concerning battery life, the A9 gets 650 shots out of its Sony NP-FZ100 battery, while the A5100 can take 400 images on a single charge of its Sony NP-FW50 power pack. The battery packs of both cameras can be charged via USB, which can be very convenient 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 A9	127 mm	96 mm	63 mm	673 g	650	Y	Apr 2017	4,499	ebay.com
2.		Sony A5100	110 mm	63 mm	36 mm	283 g	400	n	Aug 2014	549	ebay.com
3.		Nikon Z6	134 mm	101 mm	67 mm	675 g	310	Y	Aug 2018	1,999	ebay.com
4.		Sony A7R V	131 mm	97 mm	82 mm	723 g	530	Y	Oct 2022	3,899	amazon.com
5.		Sony A7R IIIA	127 mm	96 mm	74 mm	650 g	650	Y	Apr 2021	3,199	amazon.com
6.		Sony A9 II	129 mm	96 mm	76 mm	678 g	690	Y	Oct 2019	4,499	amazon.com
7.		Sony A7 III	127 mm	96 mm	74 mm	650 g	610	Y	Feb 2018	1,999	amazon.com
8.		Sony A7R III	127 mm	96 mm	74 mm	650 g	650	Y	Oct 2017	3,199	ebay.com
9.		Sony A7R II	127 mm	96 mm	60 mm	625 g	290	Y	Jun 2015	3,199	ebay.com
10.		Sony A7S II	127 mm	96 mm	60 mm	627 g	370	Y	Sep 2015	2,999	ebay.com
11.		Sony A7 II	127 mm	96 mm	60 mm	599 g	350	Y	Nov 2014	1,999	ebay.com
12.		Sony A5000	110 mm	63 mm	36 mm	269 g	420	n	Jan 2014	449	ebay.com
13.		Sony A6000	120 mm	67 mm	45 mm	344 g	360	n	Feb 2014	599	ebay.com
14.		Sony A3000	128 mm	91 mm	85 mm	411 g	470	n	Aug 2013	329	ebay.com
15.		Sony NEX-3N	110 mm	62 mm	35 mm	269 g	480	n	Feb 2013	499	ebay.com
16.		Sony A99	147 mm	111 mm	78 mm	812 g	500	Y	Sep 2012	2,799	ebay.com
17.		Sony NEX-3	117 mm	62 mm	33 mm	297 g	330	n	May 2010	599	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 A5100 was launched at a markedly lower price (by 88 percent) than the A9, 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.

Sensor comparison

The size of the imaging sensor is a crucial determinant of image quality. A large sensor will generally have larger individual pixels that offer better low-light sensitivity, provide wider dynamic range, and have 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 are more costly to manufacture and tend to lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Sony A9 features a full frame sensor and the Sony A5100 an APS-C sensor. The sensor area in the A5100 is 57 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.0 and 1.5. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

Even though the A9 has a larger sensor, both cameras offer the same resolution of 24 megapixels. This implies that the A9 has a lower pixel density and larger individual pixels (with a pixel pitch of 5.94μm versus 3.91μm for the A5100), which gives it a potential advantage in terms of light gathering capacity. In addition, the A9 is much more recent (by 2 years and 8 months) than the A5100, and its sensor will have benefitted from technological advances during this time.

The Sony Alpha A9 has a native sensitivity range from ISO 100 to ISO 51200, which can be extended to ISO 50-204800. The corresponding ISO settings for the Sony Alpha A5100 are ISO 100 to ISO 25600 (no boost).

In terms of underlying technology, the A9 is build around a Stacked BSI-CMOS sensor, while the A5100 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.

Since 2007, DXO Mark has published sensor performance measurements that have been derived using a consistent methodology. 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 review, the A9 provides substantially higher image quality than the A5100, with an overall score that is 12 points higher. This advantage is based on 1.1 bits higher color depth, 0.6 EV in additional dynamic range, and 1.4 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.		Sony A9	Full Frame	24.0	6000	4000	4K/30p	24.9	13.3	3517	92
2.		Sony A5100	APS-C	24.0	6000	4000	1080/60p	23.8	12.7	1347	80
3.		Nikon Z6	Full Frame	24.3	6048	4024	4K/30p	25.3	14.3	3299	95
4.		Sony A7R V	Full Frame	60.2	9504	6336	8k/24p	26.5	14.8	3187	100
5.		Sony A7R IIIA	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
6.		Sony A9 II	Full Frame	24.0	6000	4000	4K/30p	25.0	14.0	3434	93
7.		Sony A7 III	Full Frame	24.0	6000	4000	4K/30p	25.0	14.7	3730	96
8.		Sony A7R III	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
9.		Sony A7R II	Full Frame	42.2	7952	5304	4K/30p	26.0	13.9	3434	98
10.		Sony A7S II	Full Frame	12.0	4240	2832	4K/30p	23.6	13.3	2993	85
11.		Sony A7 II	Full Frame	24.0	6000	4000	1080/60p	24.9	13.6	2449	90
12.		Sony A5000	APS-C	19.8	5456	3632	1080/60i	23.8	13.0	1089	79
13.		Sony A6000	APS-C	24.0	6000	4000	1080/60p	24.1	13.1	1347	82
14.		Sony A3000	APS-C	19.8	5456	3632	1080/60i	23.7	12.8	1068	78
15.		Sony NEX-3N	APS-C	16.0	4912	3264	1080/60i	22.8	12.5	1067	74
16.		Sony A99	Full Frame	24.0	6000	4000	1080/60p	25.0	14.0	1555	89
17.		Sony NEX-3	APS-C	14.0	4592	3056	720/30p	22.1	12.0	830	68

Many modern cameras are not only capable of taking still images, but also of capturing video footage. Both cameras under consideration are equipped with sensors that have a sufficiently high read-out speed for moving images, but the A9 provides a higher video resolution than the A5100. It can shoot video footage at 4K/30p, while the A5100 is limited to 1080/60p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a range of features. For example, the A9 has an electronic viewfinder (3686k dots), which can be very helpful when shooting in bright sunlight. In contrast, the A5100 relies on live view and the rear LCD for framing. The table below summarizes some of the other core capabilities of the Sony A9 and Sony A5100 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	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
2.		Sony A5100	none	n	3.0 / 922	tilting	Y	1/4000s	6.0/s	Y	n
3.		Nikon Z6	3690	Y	3.2 / 2100	tilting	Y	1/8000s	12.0/s	n	Y
4.		Sony A7R V	9440	n	3.2 / 2100	full-flex	Y	1/8000s	10.0/s	n	Y
5.		Sony A7R IIIA	3686	n	3.0 / 2340	tilting	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 A7 III	2359	n	3.0 / 922	tilting	Y	1/8000s	10.0/s	n	Y
8.		Sony A7R III	3686	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
9.		Sony A7R II	2400	n	3.0 / 1229	tilting	n	1/8000s	5.0/s	n	Y
10.		Sony A7S II	2400	n	3.0 / 1229	tilting	n	1/8000s	5.0/s	n	Y
11.		Sony A7 II	2400	n	3.0 / 1230	tilting	n	1/8000s	5.0/s	n	Y
12.		Sony A5000	none	n	3.0 / 461	tilting	n	1/4000s	3.5/s	Y	n
13.		Sony A6000	1440	n	3.0 / 922	tilting	n	1/4000s	11.0/s	Y	n
14.		Sony A3000	202	n	3.0 / 230	fixed	n	1/4000s	2.5/s	Y	n
15.		Sony NEX-3N	optional	n	3.0 / 460	tilting	n	1/4000s	4.0/s	Y	n
16.		Sony A99	2359	Y	3.0 / 1229	full-flex	n	1/8000s	6.0/s	n	Y
17.		Sony NEX-3	optional	n	3.0 / 920	tilting	n	1/4000s	7.0/s	n	n
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that differentiates the A9 and the A5100 is in-body image stabilization (IBIS). The A9 reduces the risk of handshake-induced blur with all attached lenses, while the A5100 offers no blur reduction with lenses that themselves do not provide optical image stabilization.

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 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 A9 and the A5100 write their files to SDXC or Memory Stick PRO Duo cards. The A9 features dual card slots, which can be very useful in case a memory card fails. In contrast, the A5100 only has one slot. The A9 supports UHS-II cards (on its first slot), while the A5100 can use UHS-I cards.

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 and Sony Alpha A5100 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	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	Y
2.		Sony A5100	-	stereo / mono	-	-	micro	2.0	Y	Y	-
3.		Nikon Z6	Y	stereo / mono	Y	Y	micro	3.1	Y	-	Y
4.		Sony A7R V	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
5.		Sony A7R IIIA	Y	stereo / mono	Y	Y	micro	3.2	Y	Y	Y
6.		Sony A9 II	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
7.		Sony A7 III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
8.		Sony A7R III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
9.		Sony A7R II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
10.		Sony A7S II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
11.		Sony A7 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
12.		Sony A5000	-	stereo / mono	-	-	micro	2.0	Y	Y	-
13.		Sony A6000	Y	stereo / mono	-	-	micro	2.0	Y	Y	-
14.		Sony A3000	Y	stereo / mono	-	-	mini	2.0	-	-	-
15.		Sony NEX-3N	-	stereo / mono	-	-	micro	2.0	-	-	-
16.		Sony A99	Y	stereo / mono	Y	Y	mini	2.0	-	-	-
17.		Sony NEX-3	Y	stereo / mono	-	-	mini	2.0	-	-	-

It is notable that the A9 has a hotshoe, while the A5100 does not. This socket makes it possible to easily attach optional accessories, such as an external flash gun.

Studio photographers will appreciate that the Sony A9 (unlike the A5100) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the A9 and the A5100 have been discontinued, but can regularly be found used on ebay. The A9 was replaced by the Sony A9 II, while the A5100 does not have a direct successor. Further information on the features and operation of the A9 and A5100 can be found, respectively, in the Sony A9 Manual (free pdf) or the online Sony A5100 Manual.

Review summary

So how do things add up? Is the Sony A9 better than the Sony A5100 or vice versa? The listing below highlights the relative strengths of the two models.

Advantages of the Sony Alpha A9:

• Better image quality: Scores substantially higher (12 points) in the DXO overall assessment.
• Richer colors: Generates images with noticeably better colors (1.1 bits more color depth).
• More dynamic range: Captures a larger spectrum of light and dark details (0.6 EV of extra DR).
• Better low-light sensitivity: Requires less light for good images (1.4 stops ISO advantage).
• Better video: Provides higher definition movie capture (4K/30p vs 1080/60p).
• Better sound: Can connect to an external microphone for higher quality sound recording.
• Better sound control: Has a headphone port that enables audio monitoring while recording.
• Easier framing: Has an electronic viewfinder for image composition and settings control.
• More detailed LCD: Has a higher resolution rear screen (1440k vs 922k dots).
• Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
• Faster burst: Shoots at higher frequency (20 vs 6 flaps/sec) to capture the decisive moment.
• Less disturbing: Has an electronic shutter option for completely silent shooting.
• Longer lasting: Can take more shots (650 versus 400) on a single battery charge.
• Better sealing: Is weather sealed to enable shooting in dusty or wet environments.
• Sharper images: Has hand-shake reducing image stabilization built-in.
• Better lighting: Features a hotshoe and can thus hold and trigger an external flash gun.
• Easier wireless transfer: Supports Bluetooth for image sharing without cables.
• 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.
• Faster buffer clearing: Supports a more advanced SD data transfer standard (UHS-II vs UHS-I).
• More modern: Reflects 2 years and 8 months of technical progress since the A5100 launch.

Reasons to prefer the Sony Alpha A5100:

• More selfie-friendly: Has an articulated screen that can be turned to be front-facing.
• More compact: Is smaller (110x63mm vs 127x96mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 390g or 58 percent) and is thus easier to take along.
• Easier fill-in: Has a small integrated flash to brighten shadows of backlit subjects.
• More affordable: Was introduced into a lower priced category (88 percent cheaper at launch).
• More heavily discounted: Has been around for much longer (launched in August 2014).

If the number of relative strengths (bullet points above) is taken as a guide, the A9 is the clear winner of the match-up (21 : 6 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 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 A9 and the Sony A5100 place the cameras among the top in their class? Find out in the latest Best Mirrorless Interchangeable Lens Camera listing 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 partial and cannot reveal, for example, the shooting experience and imaging performance when actually working with the A9 or the A5100. 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 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 A9	5/5	+ +	4.8/5	89/100	5/5	5/5	Apr 2017	4,499	ebay.com
2.		Sony A5100	4.5/5	+	..	..	4.5/5	5/5	Aug 2014	549	ebay.com
3.		Nikon Z6	5/5	..	5/5	89/100	4.5/5	5/5	Aug 2018	1,999	ebay.com
4.		Sony A7R V	5/5	+ +	4.5/5	92/100	..	..	Oct 2022	3,899	amazon.com
5.		Sony A7R IIIA	..	+ +	4/5	90/100	4.5/5	5/5	Apr 2021	3,199	amazon.com
6.		Sony A9 II	..	..	5/5	90/100	5/5	5/5	Oct 2019	4,499	amazon.com
7.		Sony A7 III	..	+ +	4.5/5	89/100	5/5	5/5	Feb 2018	1,999	amazon.com
8.		Sony A7R III	..	+ +	4/5	90/100	4.5/5	5/5	Oct 2017	3,199	ebay.com
9.		Sony A7R II	5/5	+ +	5/5	90/100	5/5	5/5	Jun 2015	3,199	ebay.com
10.		Sony A7S II	5/5	+	..	..	4.5/5	5/5	Sep 2015	2,999	ebay.com
11.		Sony A7 II	5/5	+	4/5	82/100	4.5/5	5/5	Nov 2014	1,999	ebay.com
12.		Sony A5000	3/5	+	..	..	4.5/5	4.5/5	Jan 2014	449	ebay.com
13.		Sony A6000	5/5	+	4.5/5	80/100	4.5/5	5/5	Feb 2014	599	ebay.com
14.		Sony A3000	3/5	+	..	..	4/5	4/5	Aug 2013	329	ebay.com
15.		Sony NEX-3N	3/5	..	..	..	4.5/5	4.5/5	Feb 2013	499	ebay.com
16.		Sony A99	5/5	..	..	84/100	4.5/5	4.5/5	Sep 2012	2,799	ebay.com
17.		Sony NEX-3	..	..	..	70/100	4.5/5	4/5	May 2010	599	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The review scores listed above should be treated with care, 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 comparisons of ratings among very different cameras or across long time periods 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

Did this review help to inform your camera decision process? In case you are interested in seeing how other cameras pair up, just make your choice using the following search menu. As an alternative, you can also directly jump to any one of the listed comparisons that were previously generated by the CAM-parator tool.

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