Sony A5100 vs RX100 III

The Sony Alpha A5100 and the Sony Cyber-shot DSC-RX100 III are two digital cameras that were revealed to the public, respectively, in August 2014 and May 2014. The A5100 is a mirrorless interchangeable lens camera, while the RX100 III is a fixed lens compact. The cameras are based on an APS-C (A5100) and an one-inch (RX100 III) sensor. The A5100 has a resolution of 24 megapixels, whereas the RX100 III provides 20 MP.

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

Headline Specifications

Sony A5100		Sony RX100 III
Mirrorless system camera		Fixed lens compact camera
Sony E mount lenses		24-70mm f/1.8-2.8
24 MP – APS-C sensor		20 MP – 1" sensor
1080/60p Video		1080/60p Video
ISO 100-25,600		ISO 100-12,800 (80 - 25,600)
No viewfinder, LCD framing		Electronic viewfinder (1440k dots)
3.0" LCD – 922k dots		3.0" LCD – 1229k dots
Tilting touchscreen		Tilting screen (no touchscreen)
6 shutter flaps per second		10 shutter flaps per second
400 shots per battery charge		320 shots per battery charge
110 x 63 x 36 mm, 283 g		102 x 58 x 41 mm, 290 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Sony Alpha A5100 and the Sony Cyber-shot DSC-RX100 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 A5100 and the Sony RX100 III 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.

The A5100 can be obtained in two different colors (black, white), while the RX100 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 RX100 III is notably smaller (15 percent) than the Sony A5100. In this context, it is worth noting that neither the A5100 nor the RX100 III are weather-sealed.

The above size and weight comparisons are to some extent incomplete and possibly misleading, as the RX100 III has a lens built in, whereas the A5100 is an interchangeable lens camera that requires a separate lens. Attaching the latter will add extra weight and bulk to the setup. You can compare the optics available for the A5100 and their specifications in the Sony E-Mount Lens Catalog.

Concerning battery life, the A5100 gets 400 shots out of its NP-FW50 battery, while the RX100 III can take 320 images on a single charge of its NP-BX1 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. 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 A5100	110 mm	63 mm	36 mm	283 g	400	n	Aug 2014	549	ebay.com
2.		Sony RX100 III	102 mm	58 mm	41 mm	290 g	320	n	May 2014	799	ebay.com
3.		Canon G7 X	103 mm	60 mm	40 mm	304 g	210	n	Sep 2014	699	ebay.com
4.		Sony RX100 VII	102 mm	58 mm	43 mm	302 g	260	n	Jul 2019	1,199	amazon.com
5.		Sony RX100 IV	102 mm	58 mm	41 mm	298 g	280	n	Jun 2015	999	ebay.com
6.		Sony A5000	110 mm	63 mm	36 mm	269 g	420	n	Jan 2014	449	ebay.com
7.		Sony A6000	120 mm	67 mm	45 mm	344 g	360	n	Feb 2014	599	ebay.com
8.		Sony A3000	128 mm	91 mm	85 mm	411 g	470	n	Aug 2013	329	ebay.com
9.		Sony NEX-3N	110 mm	62 mm	35 mm	269 g	480	n	Feb 2013	499	ebay.com
10.		Sony NEX-5T	111 mm	59 mm	39 mm	276 g	330	n	Aug 2013	699	ebay.com
11.		Sony RX100 II	102 mm	58 mm	38 mm	281 g	350	n	Jun 2013	749	ebay.com
12.		Sony NEX-F3	117 mm	67 mm	42 mm	314 g	470	n	May 2012	599	ebay.com
13.		Sony RX100	102 mm	58 mm	36 mm	240 g	330	n	Jun 2012	649	ebay.com
14.		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 retail prices at the time of the camera’s release place the model in the market relative to other models in the producer’s line-up and the competition. 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. Furthermore, a large sensor camera will give the photographer more possibilities to use shallow depth-of-field in order to 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 Sony A5100 features an APS-C sensor and the Sony RX100 III an one-inch sensor. The sensor area in the RX100 III is 68 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.5 and 2.7. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

With 24MP, the A5100 offers a higher resolution than the RX100 III (20MP), but the A5100 nevertheless has larger individual pixels (pixel pitch of 3.91μm versus 2.41μm for the RX100 III) due to its larger sensor. Moreover, the A5100 is a somewhat more recent model (by 3 months) than the RX100 III, and its sensor might have benefitted from technological advances during this time that further enhance the light gathering capacity of its pixels.

The resolution advantage of the Sony A5100 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A5100 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 Sony RX100 III 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 A5100 has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

The Sony Alpha A5100 has a native sensitivity range from ISO 100 to ISO 25600. The corresponding ISO settings for the Sony Cyber-shot DSC-RX100 III are ISO 100 to ISO 12800, with the possibility to increase the ISO range to 80-25600.

In terms of underlying technology, the A5100 is build around a CMOS sensor, while the RX100 III uses a BSI-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 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 A5100 provides substantially higher image quality than the RX100 III, with an overall score that is 13 points higher. This advantage is based on 1.4 bits higher color depth, 0.4 EV in additional dynamic range, and 1.4 stops in additional low light sensitivity. The adjacent table reports on the physical sensor characteristics and the outcomes of the DXO sensor quality tests for a sample of comparator-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 A5100	APS-C	24.0	6000	4000	1080/60p	23.8	12.7	1347	80
2.		Sony RX100 III	1-inch	20.0	5472	3648	1080/60p	22.4	12.3	495	67
3.		Canon G7 X	1-inch	20.0	5472	3648	1080/60p	23.0	12.7	556	71
4.		Sony RX100 VII	1-inch	20.0	5472	3648	4K/30p	21.8	12.4	418	63
5.		Sony RX100 IV	1-inch	20.0	5472	3648	4K/30p	22.8	12.6	591	70
6.		Sony A5000	APS-C	19.8	5456	3632	1080/60i	23.8	13.0	1089	79
7.		Sony A6000	APS-C	24.0	6000	4000	1080/60p	24.1	13.1	1347	82
8.		Sony A3000	APS-C	19.8	5456	3632	1080/60i	23.7	12.8	1068	78
9.		Sony NEX-3N	APS-C	16.0	4912	3264	1080/60i	22.8	12.5	1067	74
10.		Sony NEX-5T	APS-C	16.0	4912	3264	1080/60p	23.6	13.0	1015	78
11.		Sony RX100 II	1-inch	20.0	5472	3648	1080/60p	22.5	12.4	483	67
12.		Sony NEX-F3	APS-C	16.0	4912	3264	1080/60i	22.7	12.3	1114	73
13.		Sony RX100	1-inch	20.0	5472	3648	1080/60p	22.6	12.4	390	66
14.		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 have a sensor with sufficiently fast read-out times for moving pictures, 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 RX100 III has an electronic viewfinder (1440k 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 A5100 and Sony RX100 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 A5100	none	n	3.0 / 922	tilting	Y	1/4000s	6.0/s	Y	n
2.		Sony RX100 III	1440	n	3.0 / 1229	tilting	n	1/2000s	10.0/s	Y	Y
3.		Canon G7 X	none	n	3.0 / 1040	tilting	Y	1/2000s	6.5/s	Y	Y
4.		Sony RX100 VII	2359	n	3.0 / 921	tilting	Y	1/2000s	90.0/s	Y	Y
5.		Sony RX100 IV	2359	n	3.0 / 1228	tilting	n	1/2000s	16.0/s	Y	Y
6.		Sony A5000	none	n	3.0 / 461	tilting	n	1/4000s	3.5/s	Y	n
7.		Sony A6000	1440	n	3.0 / 922	tilting	n	1/4000s	11.0/s	Y	n
8.		Sony A3000	202	n	3.0 / 230	fixed	n	1/4000s	2.5/s	Y	n
9.		Sony NEX-3N	optional	n	3.0 / 460	tilting	n	1/4000s	4.0/s	Y	n
10.		Sony NEX-5T	optional	n	3.0 / 922	tilting	Y	1/4000s	10.0/s	n	n
11.		Sony RX100 II	optional	n	3.0 / 1229	tilting	n	1/2000s	10.0/s	Y	Y
12.		Sony NEX-F3	optional	n	3.0 / 920	tilting	n	1/4000s	5.5/s	Y	n
13.		Sony RX100	none	n	3.0 / 1229	fixed	n	1/2000s	10.0/s	Y	Y
14.		Sony NEX-3	optional	n	3.0 / 920	tilting	n	1/4000s	7.0/s	n	n
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 A5100 has a touchscreen, while the RX100 III has a conventional panel. Touch control can be particularly helpful, for example, for setting the focus point.

Concerning the storage of imaging data, both the A5100 and the RX100 III write their files to SDXC or Memory Stick PRO Duo cards. 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 Sony Alpha A5100 and Sony Cyber-shot DSC-RX100 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 A5100	-	stereo / mono	-	-	micro	2.0	Y	Y	-
2.		Sony RX100 III	-	stereo / mono	-	-	micro	2.0	Y	Y	-
3.		Canon G7 X	-	stereo / mono	-	-	micro	2.0	Y	Y	-
4.		Sony RX100 VII	-	stereo / mono	Y	-	micro	2.0	Y	Y	Y
5.		Sony RX100 IV	-	stereo / mono	-	-	micro	2.0	Y	Y	-
6.		Sony A5000	-	stereo / mono	-	-	micro	2.0	Y	Y	-
7.		Sony A6000	Y	stereo / mono	-	-	micro	2.0	Y	Y	-
8.		Sony A3000	Y	stereo / mono	-	-	mini	2.0	-	-	-
9.		Sony NEX-3N	-	stereo / mono	-	-	micro	2.0	-	-	-
10.		Sony NEX-5T	Y	stereo / mono	-	-	mini	2.0	Y	Y	-
11.		Sony RX100 II	Y	stereo / mono	-	-	micro	2.0	Y	Y	-
12.		Sony NEX-F3	Y	stereo / mono	-	-	mini	2.0	-	-	-
13.		Sony RX100	-	stereo / mono	-	-	micro	2.0	-	-	-
14.		Sony NEX-3	Y	stereo / mono	-	-	mini	2.0	-	-	-

Both the A5100 and the RX100 III have been discontinued, but can regularly be found used on ebay. The RX100 III was replaced by the Sony RX100 IV, while the A5100 does not have a direct successor. Further information on the features and operation of the A5100 and RX100 III can be found, respectively, in the Sony A5100 Manual (free pdf) or the online Sony RX100 III Manual.

Review summary

So how do things add up? Is there a clear favorite between the Sony A5100 and the Sony RX100 III? Which camera is better? The listing below highlights the relative strengths of the two models.

Reasons to prefer the Sony Alpha A5100:

• More detail: Offers more megapixels (24 vs 20MP) with a 10% higher linear resolution.
• Better image quality: Scores substantially higher (13 points) in the DXO overall assessment.
• Richer colors: Generates images with noticeably better colors (1.4 bits more color depth).
• Better low-light sensitivity: Requires less light for good images (1.4 stops ISO advantage).
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• Fewer buttons to press: Is equipped with a touch-sensitive rear screen to facilitate handling.
• Faster shutter: Has higher mechanical shutter speed (1/4000s vs 1/2000s) to freeze action.
• More flexible: Accepts interchangeable lenses, so that lens characteristics can be altered.
• Longer lasting: Can take more shots (400 versus 320) on a single battery charge.
• More modern: Is somewhat more recent (announced 3 months after the RX100 III).

Advantages of the Sony Cyber-shot DSC-RX100 III:

• Easier framing: Has an electronic viewfinder for image composition and settings control.
• More detailed LCD: Has a higher resolution rear screen (1229k vs 922k dots).
• Faster burst: Shoots at higher frequency (10 vs 6 flaps/sec) to capture the decisive moment.
• Ready to shoot: Has an integrated lens, whereas the A5100 necessitates an extra lens.
• More compact: Is smaller (102x58mm vs 110x63mm) and will fit more readily into a bag.
• Sharper images: Has stabilization technology built-in to reduce the impact of hand-shake.
• More heavily discounted: Has been on the market for longer (launched in May 2014).

If the number of relative strengths (bullet points above) is taken as a guide, the A5100 emerges as the winner of the contest (10 : 7 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 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 A5100 and the Sony RX100 III place the cameras among the top in their class? Find out in the latest Best Mirrorless Interchangeable Lens Camera and Best Travel-Zoom Camera listings whether the two cameras rank among the cream of the crop.

In any case, while the comparison of technical specifications can provide a useful overview of the capabilities of different cameras, it remains partial and cannot reveal, for example, the shooting experience and imaging performance when actually working with the A5100 or the RX100 III. 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 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 A5100	4.5/5	+	..	..	4.5/5	5/5	Aug 2014	549	ebay.com
2.		Sony RX100 III	5/5	+ +	..	82/100	4.5/5	5/5	May 2014	799	ebay.com
3.		Canon G7 X	4/5	+ +	..	77/100	4.5/5	4.5/5	Sep 2014	699	ebay.com
4.		Sony RX100 VII	4.5/5	..	4/5	..	4/5	5/5	Jul 2019	1,199	amazon.com
5.		Sony RX100 IV	4.5/5	+ +	..	85/100	4/5	4.5/5	Jun 2015	999	ebay.com
6.		Sony A5000	3/5	+	..	..	4.5/5	4.5/5	Jan 2014	449	ebay.com
7.		Sony A6000	5/5	+	4.5/5	80/100	4.5/5	5/5	Feb 2014	599	ebay.com
8.		Sony A3000	3/5	+	..	..	4/5	4/5	Aug 2013	329	ebay.com
9.		Sony NEX-3N	3/5	..	..	..	4.5/5	4.5/5	Feb 2013	499	ebay.com
10.		Sony NEX-5T	..	..	..	..	4.5/5	4.5/5	Aug 2013	699	ebay.com
11.		Sony RX100 II	5/5	+ +	..	79/100	4.5/5	4.5/5	Jun 2013	749	ebay.com
12.		Sony NEX-F3	4/5	..	..	74/100	4.5/5	4.5/5	May 2012	599	ebay.com
13.		Sony RX100	5/5	+ +	..	78/100	4/5	5/5	Jun 2012	649	ebay.com
14.		Sony NEX-3	..	..	..	70/100	4.5/5	4/5	May 2010	599	ebay.com
Notes: (+ +) 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. 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. 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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