Nikon D5100 vs Sony A5100

The Nikon D5100 and the Sony Alpha A5100 are two digital cameras that were officially introduced, respectively, in April 2011 and August 2014. The D5100 is a DSLR, while the A5100 is a mirrorless interchangeable lens camera. Both cameras are equipped with an APS-C sensor. The Nikon has a resolution of 16.1 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

Nikon D5100		Sony A5100
Digital single lens reflex		Mirrorless system camera
Nikon F mount lenses		Sony E mount lenses
16.1 MP – APS-C sensor		24 MP – APS-C sensor
1080/30p Video		1080/60p Video
ISO 100-6,400 (100 - 25,600)		ISO 100-25,600
Optical viewfinder		No viewfinder, LCD framing
3.0" LCD – 921k dots		3.0" LCD – 922k dots
Swivel screen (not touch-sensitive)		Tilting touchscreen
4 shutter flaps per second		6 shutter flaps per second
660 shots per battery charge		400 shots per battery charge
128 x 97 x 79 mm, 560 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 Nikon D5100 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 Nikon D5100 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 views from the front, the top, and the rear side are shown. 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 D5100 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 (44 percent) than the Nikon D5100. Moreover, the A5100 is substantially lighter (49 percent) than the D5100. In this context, it is worth noting that neither the D5100 nor the A5100 are weather-sealed.

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. Both cameras have similarly sized sensors, but DSLRs have a larger flange-to-focal plane distance than mirrorless cameras, which imposes contraints on the optical engineering process and generally leads to bigger and heavier lenses. You can compare the optics available for the two cameras in the Nikon Lens Catalog (D5100) and the Sony E-Mount Lens Catalog (A5100). Mirrorless cameras, such as the A5100, have moreover the advantage that they can use many lenses from other systems via adapters, as they have a relatively short flange to focal plane distance.

Concerning battery life, the D5100 gets 660 shots out of its Nikon EN-EL14 battery, while the A5100 can take 400 images on a single charge of its Sony NP-FW50 power pack. The power pack in the A5100 can be charged via the USB port, which can be very convenient when travelling.

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.		Nikon D5100	128 mm	97 mm	79 mm	560 g	660	n	Apr 2011	749	ebay.com
2.		Sony A5100	110 mm	63 mm	36 mm	283 g	400	n	Aug 2014	549	ebay.com
3.		Canon 550D	129 mm	98 mm	62 mm	530 g	440	n	Feb 2010	699	ebay.com
4.		Canon G1 X	117 mm	81 mm	65 mm	534 g	250	n	Jan 2012	799	ebay.com
5.		Nikon D3100	124 mm	96 mm	75 mm	505 g	550	n	Aug 2010	599	ebay.com
6.		Nikon D3200	125 mm	96 mm	77 mm	505 g	540	n	Apr 2012	599	ebay.com
7.		Nikon D5000	127 mm	104 mm	80 mm	590 g	510	n	Apr 2009	749	ebay.com
8.		Nikon D5200	129 mm	98 mm	78 mm	555 g	500	n	Nov 2012	749	ebay.com
9.		Nikon D5300	125 mm	98 mm	76 mm	480 g	600	n	Oct 2013	799	ebay.com
10.		Nikon D5500	124 mm	97 mm	70 mm	470 g	820	n	Jan 2015	899	ebay.com
11.		Nikon D5600	124 mm	97 mm	70 mm	465 g	970	n	Nov 2016	699	ebay.com
12.		Nikon D7000	132 mm	105 mm	77 mm	780 g	1050	Y	Sep 2010	1,499	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 NEX-3N	110 mm	62 mm	35 mm	269 g	480	n	Feb 2013	499	ebay.com
16.		Sony RX100	102 mm	58 mm	36 mm	240 g	330	n	Jun 2012	649	ebay.com
17.		Sony RX100 IV	102 mm	58 mm	41 mm	298 g	280	n	Jun 2015	999	ebay.com
Note: Measurements and pricing do not include easily detachable parts, such as add-on or interchangeable lenses or optional viewfinders.
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Any camera decision will naturally be influenced heavily by the price. The manufacturer’s suggested retail prices give an idea on the placement of the camera in the maker’s lineup and the broader market. The A5100 was launched at a markedly lower price (by 27 percent) than the D5100, which puts it into a different market segment. 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 sensor inside a digital camera is one of the key determinants 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. 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 an APS-C sensor, but their sensors differ slightly in size. The sensor area in the A5100 is 1 percent smaller. They nevertheless have the same format factor of 1.5. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

Despite having a slightly smaller sensor, the A5100 offers a higher resolution of 24 megapixels, compared with 16.1 MP of the D5100. This megapixels advantage comes at the cost of a higher pixel density and a smaller size of the individual pixel (with a pixel pitch of 3.91μm versus 4.80μm for the D5100). However, it should be noted that the A5100 is much more recent (by 3 years and 4 months) than the D5100, and its sensor will have benefitted from technological advances during this time that make it possible to gather light more efficiently.

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 Nikon D5100 are 24.6 x 16.3 inches or 62.6 x 41.5 cm for good quality, 19.7 x 13.1 inches or 50.1 x 33.2 cm for very good quality, and 16.4 x 10.9 inches or 41.7 x 27.6 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 Nikon D5100 has a native sensitivity range from ISO 100 to ISO 6400, which can be extended to ISO 100-25600. The corresponding ISO settings for the Sony Alpha A5100 are ISO 100 to ISO 25600 (no boost).

Technology-wise, both cameras are equipped with CMOS (Complementary Metal–Oxide–Semiconductor) sensors. 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 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. The Overall DXO ratings for the two cameras under consideration are close, suggesting that they provide similar imaging performance. 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.		Nikon D5100	APS-C	16.1	4928	3264	1080/30p	23.5	13.6	1183	80
2.		Sony A5100	APS-C	24.0	6000	4000	1080/60p	23.8	12.7	1347	80
3.		Canon 550D	APS-C	17.9	5184	3456	1080/30p	22.1	11.5	784	66
4.		Canon G1 X	1.5-inch	14.2	4352	3264	1080/24p	21.7	10.8	644	60
5.		Nikon D3100	APS-C	14.2	4608	3072	1080/24p	22.5	11.3	919	67
6.		Nikon D3200	APS-C	24.1	6016	4000	1080/30p	24.1	13.2	1131	81
7.		Nikon D5000	APS-C	12.2	4288	2848	720/24p	22.7	12.5	868	72
8.		Nikon D5200	APS-C	24.0	6000	4000	1080/60i	24.2	13.9	1284	84
9.		Nikon D5300	APS-C	24.0	6000	4000	1080/60p	24.0	13.9	1338	83
10.		Nikon D5500	APS-C	24.0	6000	4000	1080/60p	24.1	14.0	1438	84
11.		Nikon D5600	APS-C	24.0	6000	4000	1080/60p	24.1	14.0	1306	84
12.		Nikon D7000	APS-C	16.1	4928	3264	1080/24p	23.5	13.9	1167	80
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 NEX-3N	APS-C	16.0	4912	3264	1080/60i	22.8	12.5	1067	74
16.		Sony RX100	1-inch	20.0	5472	3648	1080/60p	22.6	12.4	390	66
17.		Sony RX100 IV	1-inch	20.0	5472	3648	4K/30p	22.8	12.6	591	70

Many modern cameras are not only capable of taking still images, but can also record movies. The two cameras under consideration both have sensors whose read-out speed is fast enough to capture moving pictures, but the A5100 provides a faster frame rate than the D5100. It can shoot movie footage at 1080/60p, while the Nikon is limited to 1080/30p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. For example, the D5100 has an optical viewfinder, which can be very useful 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 Nikon D5100, 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.		Nikon D5100	optical	n	3.0 / 921	swivel	n	1/4000s	4.0/s	Y	n
2.		Sony A5100	none	n	3.0 / 922	tilting	Y	1/4000s	6.0/s	Y	n
3.		Canon 550D	optical	n	3.0 / 1040	fixed	n	1/4000s	3.7/s	Y	n
4.		Canon G1 X	optical	n	3.0 / 922	swivel	n	1/4000s	1.9/s	Y	Y
5.		Nikon D3100	optical	n	3.0 / 230	fixed	n	1/4000s	3.0/s	Y	n
6.		Nikon D3200	optical	n	3.0 / 921	fixed	n	1/4000s	4.0/s	Y	n
7.		Nikon D5000	optical	n	2.7 / 230	full-flex	n	1/4000s	4.0/s	Y	n
8.		Nikon D5200	optical	n	3.0 / 921	swivel	n	1/4000s	5.0/s	Y	n
9.		Nikon D5300	optical	n	3.2 / 1037	swivel	n	1/4000s	5.0/s	Y	n
10.		Nikon D5500	optical	n	3.2 / 1037	swivel	Y	1/4000s	5.0/s	Y	n
11.		Nikon D5600	optical	n	3.2 / 1037	swivel	Y	1/4000s	5.0/s	Y	n
12.		Nikon D7000	optical	Y	3.0 / 921	fixed	n	1/8000s	6.0/s	Y	n
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 NEX-3N	optional	n	3.0 / 460	tilting	n	1/4000s	4.0/s	Y	n
16.		Sony RX100	none	n	3.0 / 1229	fixed	n	1/2000s	10.0/s	Y	Y
17.		Sony RX100 IV	2359	n	3.0 / 1228	tilting	n	1/2000s	16.0/s	Y	Y
Note: *) 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 D5100 has a conventional panel. Touch control can be particularly helpful, for example, for setting the focus point.

The Nikon D5100 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 D5100 writes its imaging data to SDXC cards, while the A5100 uses 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 Nikon D5100 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.		Nikon D5100	Y	mono / mono	Y	-	mini	2.0	-	-	-
2.		Sony A5100	-	stereo / mono	-	-	micro	2.0	Y	Y	-
3.		Canon 550D	Y	stereo / -	Y	-	mini	2.0	-	-	-
4.		Canon G1 X	Y	stereo / mono	-	-	mini	2.0	-	-	-
5.		Nikon D3100	Y	mono / mono	-	-	mini	2.0	-	-	-
6.		Nikon D3200	Y	mono / mono	Y	-	mini	2.0	-	-	-
7.		Nikon D5000	Y	mono / mono	-	-	mini	2.0	-	-	-
8.		Nikon D5200	Y	stereo / mono	Y	-	mini	2.0	-	-	-
9.		Nikon D5300	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
10.		Nikon D5500	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
11.		Nikon D5600	Y	stereo / mono	Y	-	mini	2.0	Y	Y	Y
12.		Nikon D7000	Y	mono / mono	Y	-	mini	2.0	-	-	-
13.		Sony A5000	-	stereo / mono	-	-	micro	2.0	Y	Y	-
14.		Sony A6000	Y	stereo / mono	-	-	micro	2.0	Y	Y	-
15.		Sony NEX-3N	-	stereo / mono	-	-	micro	2.0	-	-	-
16.		Sony RX100	-	stereo / mono	-	-	micro	2.0	-	-	-
17.		Sony RX100 IV	-	stereo / mono	-	-	micro	2.0	Y	Y	-

It is notable that the D5100 has a hotshoe, while the A5100 does not. This socket makes it possible to easily attach optional accessories, such as an external flash gun.

Both the D5100 and the A5100 have been discontinued, but can regularly be found used on ebay. The D5100 was replaced by the Nikon D5200, while the A5100 does not have a direct successor. Further information on the features and operation of the D5100 and A5100 can be found, respectively, in the Nikon D5100 Manual (free pdf) or the online Sony A5100 Manual.

Review summary

So how do things add up? Is the Nikon D5100 better than the Sony A5100 or vice versa? Below is a summary of the relative strengths of each of the two contestants.

Arguments in favor of the Nikon D5100:

• More dynamic range: Captures a larger spectrum of light and dark details (0.9 EV of extra DR).
• Better sound: Can connect to an external microphone for higher quality sound recording.
• Easier framing: Has an optical viewfinder for image composition and settings control.
• More flexible LCD: Has a swivel screen for odd-angle shots in portrait or landscape orientation.
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• Longer lasting: Can take more shots (660 versus 400) on a single battery charge.
• Better lighting: Features a hotshoe and can thus hold and trigger an external flash gun.
• More heavily discounted: Has been available for much longer (launched in April 2011).

Reasons to prefer the Sony Alpha A5100:

• More detail: Has more megapixels (24 vs 16.1MP), which boosts linear resolution by 22%.
• Better video: Provides higher movie framerates (1080/60p versus 1080/30p).
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• Fewer buttons to press: Has a touchscreen to facilitate handling and shooting adjustments.
• Faster burst: Shoots at higher frequency (6 vs 4 flaps/sec) to capture the decisive moment.
• More compact: Is smaller (110x63mm vs 128x97mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 277g or 49 percent) and is thus easier to take along.
• Easier travel charging: Can be conveniently charged via its USB port.
• More legacy lens friendly: Can use many non-native lenses via adapters.
• 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 into a lower priced category (27 percent cheaper at launch).
• More modern: Reflects 3 years and 4 months of technical progress since the D5100 launch.

If the count of relative strengths (bullet points above) is taken as a measure, the A5100 is the clear winner of the contest (13 : 8 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 Nikon D5100 and the Sony A5100 place the cameras among the top in their class? Find out in the latest Best DSLR Camera and Best Mirrorless Interchangeable Lens 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 D5100 or the A5100. 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 hands-on reviews by experts 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.		Nikon D5100	5/5	+ +	..	76/100	4.5/5	4.5/5	Apr 2011	749	ebay.com
2.		Sony A5100	4.5/5	+	..	..	4.5/5	5/5	Aug 2014	549	ebay.com
3.		Canon 550D	..	+ +	..	77/100	4/5	4.5/5	Feb 2010	699	ebay.com
4.		Canon G1 X	5/5	+	..	76/100	4/5	4.5/5	Jan 2012	799	ebay.com
5.		Nikon D3100	5/5	+ +	..	72/100	4.5/5	4.5/5	Aug 2010	599	ebay.com
6.		Nikon D3200	5/5	+ +	..	73/100	4.5/5	4.5/5	Apr 2012	599	ebay.com
7.		Nikon D5000	..	+ +	..	75/100	4/5	4.5/5	Apr 2009	749	ebay.com
8.		Nikon D5200	4/5	+ +	..	79/100	4.5/5	4.5/5	Nov 2012	749	ebay.com
9.		Nikon D5300	4/5	+ +	..	79/100	4.5/5	4.5/5	Oct 2013	799	ebay.com
10.		Nikon D5500	5/5	+	..	79/100	4.5/5	4.5/5	Jan 2015	899	ebay.com
11.		Nikon D5600	4/5	..	4/5	79/100	4.5/5	4/5	Nov 2016	699	ebay.com
12.		Nikon D7000	4/5	..	..	80/100	4.5/5	4.5/5	Sep 2010	1,499	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 NEX-3N	3/5	..	..	..	4.5/5	4.5/5	Feb 2013	499	ebay.com
16.		Sony RX100	5/5	+ +	..	78/100	4/5	5/5	Jun 2012	649	ebay.com
17.		Sony RX100 IV	4.5/5	+ +	..	85/100	4/5	4.5/5	Jun 2015	999	ebay.com
Note: (+ +) 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. 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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