Sony A7 III vs A5100

The Sony Alpha A7 III and the Sony Alpha A5100 are two digital cameras that were officially introduced, respectively, in February 2018 and August 2014. Both the A7 III and the A5100 are mirrorless interchangeable lens cameras that are based on a full frame (A7 III) 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 A7 III		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 (2359k dots)		No viewfinder, LCD framing
3.0" LCD – 922k dots		3.0" LCD – 922k dots
Tilting touchscreen		Tilting touchscreen
10 shutter flaps per second		6 shutter flaps per second
In-body stabilization		Lens stabilization only
Weathersealed body		not weather sealed
610 shots per battery charge		400 shots per battery charge
127 x 96 x 74 mm, 650 g		110 x 63 x 36 mm, 283 g

Check A7 III price at
amazon.com
Check A5100 offers at
ebay.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Sony Alpha A7 III 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

The physical size and weight of the Sony A7 III and the Sony A5100 are illustrated 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 width, height and depth dimensions are rounded to the nearest millimeter.

The A5100 can be obtained in two different colors (black, white), while the A7 III 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 A7 III. Moreover, the A5100 is substantially lighter (56 percent) than the A7 III. It is worth mentioning in this context that the A7 III 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 (A7 III) 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 A7 III gets 610 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 adjacent table lists the principal physical characteristics of the two cameras alongside a wider set of alternatives. If you want to switch the focus of the display and review another camera pair, you can move across to the CAM-parator tool and choose from the broad selection of possible camera comparisons there.

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 A7 III	127 mm	96 mm	74 mm	650 g	610	Y	Feb 2018	1,999	amazon.com
2.		Sony A5100	110 mm	63 mm	36 mm	283 g	400	n	Aug 2014	549	ebay.com
3.		Canon 6D Mark II	144 mm	111 mm	75 mm	765 g	1200	Y	Jun 2017	1,999	amazon.com
4.		Nikon Z6	134 mm	101 mm	67 mm	675 g	310	Y	Aug 2018	1,999	ebay.com
5.		Sony A7 IV	131 mm	96 mm	80 mm	659 g	580	Y	Oct 2021	2,499	amazon.com
6.		Sony A7R IIIA	127 mm	96 mm	74 mm	650 g	650	Y	Apr 2021	3,199	amazon.com
7.		Sony A7C	124 mm	71 mm	60 mm	509 g	740	Y	Sep 2020	1,799	amazon.com
8.		Sony A9 II	129 mm	96 mm	76 mm	678 g	690	Y	Oct 2019	4,499	amazon.com
9.		Sony A7R IV	129 mm	96 mm	78 mm	665 g	670	Y	Jul 2019	3,499	ebay.com
10.		Sony A7R III	127 mm	96 mm	74 mm	650 g	650	Y	Oct 2017	3,199	ebay.com
11.		Sony A9	127 mm	96 mm	63 mm	673 g	650	Y	Apr 2017	4,499	ebay.com
12.		Sony A7 II	127 mm	96 mm	60 mm	599 g	350	Y	Nov 2014	1,999	ebay.com
13.		Sony A5000	110 mm	63 mm	36 mm	269 g	420	n	Jan 2014	449	ebay.com
14.		Sony A6000	120 mm	67 mm	45 mm	344 g	360	n	Feb 2014	599	ebay.com
15.		Sony A3000	128 mm	91 mm	85 mm	411 g	470	n	Aug 2013	329	ebay.com
16.		Sony NEX-3N	110 mm	62 mm	35 mm	269 g	480	n	Feb 2013	499	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

Any camera decision will naturally be influenced heavily by the price. 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 73 percent) than the A7 III, 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. Then, after the new model is out, very good deals can frequently be found on the pre-owned market.

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. 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 more expensive and lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Sony A7 III 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 A7 III has a larger sensor, both cameras offer the same resolution of 24 megapixels. This implies that the A7 III 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 A7 III is much more recent (by 3 years and 6 months) than the A5100, and its sensor will have benefitted from technological advances during this time.

The Sony Alpha A7 III 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 A7 III is build around a 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.

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 A7 III provides substantially higher image quality than the A5100, with an overall score that is 16 points higher. This advantage is based on 1.2 bits higher color depth, 2 EV in additional dynamic range, and 1.5 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 A7 III	Full Frame	24.0	6000	4000	4K/30p	25.0	14.7	3730	96
2.		Sony A5100	APS-C	24.0	6000	4000	1080/60p	23.8	12.7	1347	80
3.		Canon 6D Mark II	Full Frame	26.0	6240	4160	1080/60p	24.4	11.9	2862	85
4.		Nikon Z6	Full Frame	24.3	6048	4024	4K/30p	25.3	14.3	3299	95
5.		Sony A7 IV	Full Frame	32.7	7008	4672	4K/60p	25.4	14.7	3379	97
6.		Sony A7R IIIA	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
7.		Sony A7C	Full Frame	24.0	6000	4000	4K/30p	25.0	14.7	3407	95
8.		Sony A9 II	Full Frame	24.0	6000	4000	4K/30p	25.0	14.0	3434	93
9.		Sony A7R IV	Full Frame	60.2	9504	6336	4K/30p	26.0	14.8	3344	99
10.		Sony A7R III	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
11.		Sony A9	Full Frame	24.0	6000	4000	4K/30p	24.9	13.3	3517	92
12.		Sony A7 II	Full Frame	24.0	6000	4000	1080/60p	24.9	13.6	2449	90
13.		Sony A5000	APS-C	19.8	5456	3632	1080/60i	23.8	13.0	1089	79
14.		Sony A6000	APS-C	24.0	6000	4000	1080/60p	24.1	13.1	1347	82
15.		Sony A3000	APS-C	19.8	5456	3632	1080/60i	23.7	12.8	1068	78
16.		Sony NEX-3N	APS-C	16.0	4912	3264	1080/60i	22.8	12.5	1067	74
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 can also record movies. Both cameras under consideration have a sensor with sufficiently fast read-out times for moving pictures, but the A7 III 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

Beyond body and sensor, cameras can and do differ across a range of features. For example, the A7 III has an electronic viewfinder (2359k 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 following table reports on some other key feature differences and similarities of the Sony A7 III, the Sony A5100, and comparable 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 A7 III	2359	n	3.0 / 922	tilting	Y	1/8000s	10.0/s	n	Y
2.		Sony A5100	none	n	3.0 / 922	tilting	Y	1/4000s	6.0/s	Y	n
3.		Canon 6D Mark II	optical	Y	3.0 / 1040	swivel	Y	1/4000s	6.5/s	n	n
4.		Nikon Z6	3690	Y	3.2 / 2100	tilting	Y	1/8000s	12.0/s	n	Y
5.		Sony A7 IV	3686	n	3.0 / 1037	swivel	Y	1/8000s	10.0/s	n	Y
6.		Sony A7R IIIA	3686	n	3.0 / 2340	tilting	Y	1/8000s	10.0/s	n	Y
7.		Sony A7C	2360	n	3.0 / 922	swivel	Y	1/4000s	10.0/s	n	Y
8.		Sony A9 II	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
9.		Sony A7R IV	5760	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
10.		Sony A7R III	3686	n	3.0 / 1440	tilting	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 A7 II	2400	n	3.0 / 1230	tilting	n	1/8000s	5.0/s	n	Y
13.		Sony A5000	none	n	3.0 / 461	tilting	n	1/4000s	3.5/s	Y	n
14.		Sony A6000	1440	n	3.0 / 922	tilting	n	1/4000s	11.0/s	Y	n
15.		Sony A3000	202	n	3.0 / 230	fixed	n	1/4000s	2.5/s	Y	n
16.		Sony NEX-3N	optional	n	3.0 / 460	tilting	n	1/4000s	4.0/s	Y	n
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 A7 III and the A5100 is in-body image stabilization (IBIS). The A7 III 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 A7 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 A7 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.

Concerning the storage of imaging data, both the A7 III and the A5100 write their files to SDXC or Memory Stick PRO Duo cards. The A7 III features dual card slots, which can be very useful in case a memory card fails. In contrast, the A5100 only has one slot. The A7 III 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 A7 III 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 A7 III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
2.		Sony A5100	-	stereo / mono	-	-	micro	2.0	Y	Y	-
3.		Canon 6D Mark II	Y	stereo / mono	Y	-	mini	2.0	Y	Y	Y
4.		Nikon Z6	Y	stereo / mono	Y	Y	micro	3.1	Y	-	Y
5.		Sony A7 IV	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
6.		Sony A7R IIIA	Y	stereo / mono	Y	Y	micro	3.2	Y	Y	Y
7.		Sony A7C	Y	stereo / mono	Y	Y	micro	3.2	Y	Y	Y
8.		Sony A9 II	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
9.		Sony A7R IV	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
10.		Sony A7R III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
11.		Sony A9	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	Y
12.		Sony A7 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
13.		Sony A5000	-	stereo / mono	-	-	micro	2.0	Y	Y	-
14.		Sony A6000	Y	stereo / mono	-	-	micro	2.0	Y	Y	-
15.		Sony A3000	Y	stereo / mono	-	-	mini	2.0	-	-	-
16.		Sony NEX-3N	-	stereo / mono	-	-	micro	2.0	-	-	-
17.		Sony NEX-3	Y	stereo / mono	-	-	mini	2.0	-	-	-

It is notable that the A7 III has a hotshoe, while the A5100 does not. This socket makes it possible to easily attach optional accessories, such as an external flash gun.

The A7 III is a recent model that features in the current product line-up of Sony. In contrast, the A5100 has been discontinued (but can be found pre-owned on ebay). There has not been a direct replacement model for the A5100 from Sony. Further information on the features and operation of the A7 III and A5100 can be found, respectively, in the Sony A7 III Manual (free pdf) or the online Sony A5100 Manual.

Review summary

So what is the bottom line? Is there a clear favorite between the Sony A7 III and the Sony A5100? Which camera is better? Below is a summary of the relative strengths of each of the two contestants.

Reasons to prefer the Sony Alpha A7 III:

• Better image quality: Scores substantially higher (16 points) in the DXO overall assessment.
• Richer colors: Generates images with noticeably better colors (1.2 bits more color depth).
• More dynamic range: Captures a larger spectrum of light and dark details (2 EV of extra DR).
• Better low-light sensitivity: Requires less light for good images (1.5 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.
• Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
• Faster burst: Shoots at higher frequency (10 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.
• Longer lasting: Can take more shots (610 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.
• Faster data transfer: Supports a more advanced USB protocol (3.1 vs 2.0).
• 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 3 years and 6 months of technical progress since the A5100 launch.

Arguments in favor of 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 367g or 56 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 (73 percent cheaper at launch).
• More heavily discounted: Has been around for much longer (launched in August 2014).

If the count of relative strengths (bullet points above) is taken as a measure, the A7 III is the clear winner of the match-up (21 : 6 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 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 A7 III 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 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 A7 III and the A5100 in practical situations. User reviews that are available, for instance, at amazon can sometimes shed light on these issues, but such feedback is all too often partial, inconsistent, and inaccurate.

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 (USD)	Street Price
1.		Sony A7 III	..	+ +	4.5/5	89/100	5/5	5/5	Feb 2018	1,999	amazon.com
2.		Sony A5100	4.5/5	+	..	..	4.5/5	5/5	Aug 2014	549	ebay.com
3.		Canon 6D Mark II	4/5	+	4/5	80/100	4.5/5	4/5	Jun 2017	1,999	amazon.com
4.		Nikon Z6	5/5	..	5/5	89/100	4.5/5	5/5	Aug 2018	1,999	ebay.com
5.		Sony A7 IV	5/5	+ +	4.5/5	89/100	4.5/5	4.5/5	Oct 2021	2,499	amazon.com
6.		Sony A7R IIIA	..	+ +	4/5	90/100	4.5/5	5/5	Apr 2021	3,199	amazon.com
7.		Sony A7C	3.5/5	..	3.5/5	86/100	4/5	4/5	Sep 2020	1,799	amazon.com
8.		Sony A9 II	..	..	5/5	90/100	5/5	5/5	Oct 2019	4,499	amazon.com
9.		Sony A7R IV	5/5	+	4.5/5	91/100	4.5/5	5/5	Jul 2019	3,499	ebay.com
10.		Sony A7R III	..	+ +	4/5	90/100	4.5/5	5/5	Oct 2017	3,199	ebay.com
11.		Sony A9	5/5	+ +	4.8/5	89/100	5/5	5/5	Apr 2017	4,499	ebay.com
12.		Sony A7 II	5/5	+	4/5	82/100	4.5/5	5/5	Nov 2014	1,999	ebay.com
13.		Sony A5000	3/5	+	..	..	4.5/5	4.5/5	Jan 2014	449	ebay.com
14.		Sony A6000	5/5	+	4.5/5	80/100	4.5/5	5/5	Feb 2014	599	ebay.com
15.		Sony A3000	3/5	+	..	..	4/5	4/5	Aug 2013	329	ebay.com
16.		Sony NEX-3N	3/5	..	..	..	4.5/5	4.5/5	Feb 2013	499	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 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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