Nikon D3100 vs Sony A68

The Nikon D3100 and the Sony Alpha SLT-A68 are two digital cameras that were officially introduced, respectively, in August 2010 and November 2015. Both are DSLR (Digital Single Lens Reflex) cameras that are equipped with an APS-C sensor. The Nikon has a resolution of 14.2 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 D3100		Sony A68
Digital single lens reflex		Digital single lens reflex
Nikon F mount lenses		Sony A mount lenses
14.2 MP – APS-C sensor		24 MP – APS-C sensor
1080/24p Video		1080/60i Video
ISO 100-3,200 (100 - 12,800)		ISO 100-25,600
Optical viewfinder		Electronic viewfinder (1440k dots)
3.0" LCD – 230k dots		2.7" LCD – 460k dots
Fixed screen (not touch-sensitive)		Tilting screen (no touchscreen)
3 shutter flaps per second		8 shutter flaps per second
Lens stabilization only		In-body stabilization
550 shots per battery charge		540 shots per battery charge
124 x 96 x 75 mm, 505 g		143 x 104 x 81 mm, 610 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Nikon D3100 and the Sony Alpha SLT-A68? 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 side-by-side display below illustrates the physical size and weight of the Nikon D3100 and the Sony A68. 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 D3100 can be obtained in two different colors (black, red), while the A68 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 A68 is notably larger (25 percent) than the Nikon D3100. Moreover, the A68 is markedly heavier (21 percent) than the D3100. In this context, it is worth noting that neither the D3100 nor the A68 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. Hence, you might want to study and compare the specifications of available lenses in order to get the full picture of the size and weight of the two camera systems.

Concerning battery life, the D3100 gets 550 shots out of its Nikon EN-EL14 battery, while the A68 can take 540 images on a single charge of its Sony NP-FM500H power pack.

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.		Nikon D3100	124 mm	96 mm	75 mm	505 g	550	n	Aug 2010	599	ebay.com
2.		Sony A68	143 mm	104 mm	81 mm	610 g	540	n	Nov 2015	699	ebay.com
3.		Nikon D40	124 mm	94 mm	64 mm	522 g	470	n	Nov 2006	499	ebay.com
4.		Nikon D40X	124 mm	94 mm	64 mm	522 g	520	n	Mar 2007	729	ebay.com
5.		Nikon D60	126 mm	94 mm	64 mm	522 g	500	n	Jan 2008	629	ebay.com
6.		Nikon D3000	126 mm	97 mm	64 mm	536 g	500	n	Jul 2009	599	ebay.com
7.		Nikon D3200	125 mm	96 mm	77 mm	505 g	540	n	Apr 2012	599	ebay.com
8.		Nikon D5000	127 mm	104 mm	80 mm	590 g	510	n	Apr 2009	749	ebay.com
9.		Nikon D5100	128 mm	97 mm	79 mm	560 g	660	n	Apr 2011	749	ebay.com
10.		Nikon D7000	132 mm	105 mm	77 mm	780 g	1050	Y	Sep 2010	1,499	ebay.com
11.		Pentax K-S1	121 mm	93 mm	70 mm	558 g	410	n	Aug 2014	749	ebay.com
12.		Sony A58	129 mm	95 mm	78 mm	492 g	690	n	Feb 2013	599	ebay.com
13.		Sony A77	143 mm	104 mm	81 mm	732 g	470	Y	Aug 2011	1,399	ebay.com
14.		Sony A77 II	143 mm	104 mm	81 mm	647 g	480	Y	May 2014	1,199	ebay.com
15.		Sony A6000	120 mm	67 mm	45 mm	344 g	360	n	Feb 2014	599	ebay.com
16.		Sony NEX-5N	111 mm	59 mm	38 mm	269 g	460	n	Aug 2011	699	ebay.com
17.		Sony NEX-C3	110 mm	60 mm	33 mm	225 g	400	n	Jun 2011	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 D3100 was launched at a somewhat lower price (by 14 percent) than the A68, which makes it more attractive for photographers on a tight budget. 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. 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.

Both cameras under consideration feature an APS-C sensor, but their sensors differ slightly in size. The sensor area in the A68 is 3 percent bigger. 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.

With 24MP, the A68 offers a higher resolution than the D3100 (14.2MP), but the A68 has smaller individual pixels (pixel pitch of 3.91μm versus 5.01μm for the D3100). Yet, the A68 is a much more recent model (by 5 years and 2 months) than the D3100, 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 A68 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A68 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 D3100 are 23 x 15.4 inches or 58.5 x 39 cm for good quality, 18.4 x 12.3 inches or 46.8 x 31.2 cm for very good quality, and 15.4 x 10.2 inches or 39 x 26 cm for excellent quality prints.

The Nikon D3100 has a native sensitivity range from ISO 100 to ISO 3200, which can be extended to ISO 100-12800. The corresponding ISO settings for the Sony Alpha SLT-A68 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.

Consistent information on actual sensor performance is available from DXO Mark for many cameras. 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 consideration, the A68 offers substantially better image quality than the D3100 (overall score 12 points higher). The advantage is based on 1.6 bits higher color depth, 2.2 EV in additional dynamic range, and 0.4 stops of reduced 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.		Nikon D3100	APS-C	14.2	4608	3072	1080/24p	22.5	11.3	919	67
2.		Sony A68	APS-C	24.0	6000	4000	1080/60i	24.1	13.5	701	79
3.		Nikon D40	APS-C	6.0	3008	2000	none	21.0	11.0	561	56
4.		Nikon D40X	APS-C	10.0	3872	2592	none	22.4	11.4	516	63
5.		Nikon D60	APS-C	10.0	3872	2592	none	22.5	11.4	562	65
6.		Nikon D3000	APS-C	10.0	3872	2592	none	22.3	11.1	563	62
7.		Nikon D3200	APS-C	24.1	6016	4000	1080/30p	24.1	13.2	1131	81
8.		Nikon D5000	APS-C	12.2	4288	2848	720/24p	22.7	12.5	868	72
9.		Nikon D5100	APS-C	16.1	4928	3264	1080/30p	23.5	13.6	1183	80
10.		Nikon D7000	APS-C	16.1	4928	3264	1080/24p	23.5	13.9	1167	80
11.		Pentax K-S1	APS-C	20.0	5472	3648	1080/30p	23.5	13.0	1061	78
12.		Sony A58	APS-C	19.8	5456	3632	1080/60i	23.3	12.5	753	74
13.		Sony A77	APS-C	24.0	6000	4000	1080/60p	24.0	13.2	801	78
14.		Sony A77 II	APS-C	24.0	6000	4000	1080/60p	24.4	13.4	1013	82
15.		Sony A6000	APS-C	24.0	6000	4000	1080/60p	24.1	13.1	1347	82
16.		Sony NEX-5N	APS-C	16.0	4912	3264	1080/60i	23.6	12.7	1079	77
17.		Sony NEX-C3	APS-C	16.0	4912	3264	720/30p	22.7	12.2	1083	73

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, but the A68 provides a faster frame rate than the D3100. It can shoot movie footage at 1080/60i, while the Nikon is limited to 1080/24p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a range of features. For example, the A68 has an electronic viewfinder (1440k dots), while the D3100 has an optical one. Both systems have their advantages, with the electronic viewfinder making it possible to project supplementary shooting information into the framing view, whereas the optical viewfinder offers lag-free viewing and a very clear framing image. The viewfinder in the A68 offers a wider field of view (100%) than the one in the D3100 (95%), so that a larger proportion of the captured image is visible in the finder. In addition, the viewfinder of the A68 has a higher magnification (0.57x vs 0.53x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The table below summarizes some of the other core capabilities of the Nikon D3100 and Sony A68 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.		Nikon D3100	optical	n	3.0 / 230	fixed	n	1/4000s	3.0/s	Y	n
2.		Sony A68	1440	Y	2.7 / 460	tilting	n	1/4000s	8.0/s	Y	Y
3.		Nikon D40	optical	n	2.5 / 230	fixed	n	1/4000s	2.5/s	Y	n
4.		Nikon D40X	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
5.		Nikon D60	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
6.		Nikon D3000	optical	n	3.0 / 230	fixed	n	1/4000s	3.0/s	Y	n
7.		Nikon D3200	optical	n	3.0 / 921	fixed	n	1/4000s	4.0/s	Y	n
8.		Nikon D5000	optical	n	2.7 / 230	full-flex	n	1/4000s	4.0/s	Y	n
9.		Nikon D5100	optical	n	3.0 / 921	swivel	n	1/4000s	4.0/s	Y	n
10.		Nikon D7000	optical	Y	3.0 / 921	fixed	n	1/8000s	6.0/s	Y	n
11.		Pentax K-S1	optical	n	3.0 / 921	fixed	n	1/6000s	5.4/s	Y	Y
12.		Sony A58	1440	n	2.7 / 460	tilting	n	1/4000s	5.0/s	Y	Y
13.		Sony A77	2359	Y	3.0 / 921	full-flex	n	1/8000s	12.0/s	Y	Y
14.		Sony A77 II	2359	Y	3.0 / 1229	full-flex	n	1/8000s	12.0/s	Y	Y
15.		Sony A6000	1440	n	3.0 / 922	tilting	n	1/4000s	11.0/s	Y	n
16.		Sony NEX-5N	optional	n	3.0 / 920	tilting	Y	1/4000s	10.0/s	n	n
17.		Sony NEX-C3	optional	n	3.0 / 920	tilting	n	1/4000s	5.5/s	n	n
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that differentiates the A68 and the D3100 is in-body image stabilization (IBIS). The A68 reduces the risk of handshake-induced blur with all attached lenses, while the D3100 offers no blur reduction with lenses that themselves do not provide optical image stabilization.

The D3100 writes its imaging data to SDXC cards, while the A68 uses SDXC or Memory Stick PRO Duo cards. The A68 supports UHS-I cards (Ultra High Speed data transfer of up to 104 MB/s), while the D3100 cannot take advantage of Ultra High Speed SD 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 Nikon D3100 and Sony Alpha SLT-A68 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 D3100	Y	mono / mono	-	-	mini	2.0	-	-	-
2.		Sony A68	Y	stereo / mono	Y	-	micro	2.0	-	-	-
3.		Nikon D40	Y	- / -	-	-	-	2.0	-	-	-
4.		Nikon D40X	Y	- / -	-	-	-	2.0	-	-	-
5.		Nikon D60	Y	- / -	-	-	-	2.0	-	-	-
6.		Nikon D3000	Y	- / -	-	-	-	2.0	-	-	-
7.		Nikon D3200	Y	mono / mono	Y	-	mini	2.0	-	-	-
8.		Nikon D5000	Y	mono / mono	-	-	mini	2.0	-	-	-
9.		Nikon D5100	Y	mono / mono	Y	-	mini	2.0	-	-	-
10.		Nikon D7000	Y	mono / mono	Y	-	mini	2.0	-	-	-
11.		Pentax K-S1	Y	stereo / mono	-	-	micro	2.0	-	-	-
12.		Sony A58	Y	stereo / mono	Y	-	mini	2.0	-	-	-
13.		Sony A77	Y	stereo / mono	Y	-	mini	2.0	-	-	-
14.		Sony A77 II	Y	stereo / mono	Y	-	mini	2.0	Y	Y	-
15.		Sony A6000	Y	stereo / mono	-	-	micro	2.0	Y	Y	-
16.		Sony NEX-5N	Y	stereo / mono	-	-	mini	2.0	-	-	-
17.		Sony NEX-C3	Y	stereo / mono	-	-	mini	2.0	-	-	-

It is notable that the A68 has a microphone port, which can help to improve the quality of audio recordings by attaching an external microphone. The D3100 does not feature such a mic input.

Both the D3100 and the A68 have been discontinued, but can regularly be found used on ebay. The D3100 was replaced by the Nikon D3200, while the A68 does not have a direct successor. Further information on the features and operation of the D3100 and A68 can be found, respectively, in the Nikon D3100 Manual (free pdf) or the online Sony A68 Manual.

Review summary

So how do things add up? Is the Nikon D3100 better than the Sony A68 or vice versa? Below is a summary of the relative strengths of each of the two contestants.

Reasons to prefer the Nikon D3100:

• Better low-light sensitivity: Requires less light for good images (0.4 stops ISO advantage).
• Brighter framing: Features an optical viewfinder for clear, lag-free composition.
• Larger screen: Has a bigger rear LCD (3.0" vs 2.7") for image review and settings control.
• More compact: Is smaller (124x96mm vs 143x104mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 105g or 17 percent) and hence easier to carry around.
• More affordable: Was introduced into a lower priced segment (14 percent cheaper at launch).
• More heavily discounted: Has been available for much longer (launched in August 2010).

Advantages of the Sony Alpha SLT-A68:

• More detail: Has more megapixels (24 vs 14.2MP), which boosts linear resolution by 30%.
• Better image quality: Scores substantially higher (12 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (1.6 bits more color depth).
• More dynamic range: Captures a broader range of light and dark details (2.2 EV of extra DR).
• Better video: Provides higher movie framerates (1080/60i versus 1080/24p).
• Better sound: Can connect to an external microphone for higher quality sound recording.
• More framing info: Has an electronic viewfinder that displays shooting data.
• More complete view: Has a viewfinder with a larger field of view (100% vs 95%).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.57x vs 0.53x).
• Easier setting verification: Features a control panel on top to check shooting parameters.
• More detailed LCD: Has a higher resolution rear screen (460k vs 230k dots).
• More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
• Faster burst: Shoots at higher frequency (8 vs 3 flaps/sec) to capture the decisive moment.
• Sharper images: Has stabilization technology built-in to reduce the impact of hand-shake.
• Faster buffer clearing: Has an SD card interface that supports the UHS-I standard.
• More modern: Reflects 5 years and 2 months of technical progress since the D3100 launch.

If the count of individual advantages (bullet points above) is taken as a guide, the A68 is the clear winner of the contest (16 : 7 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 sports photographer will view the differences between cameras in a way that diverges from the perspective of a street photog, and a person interested in family portraits has distinct needs from a landscape 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 D3100 and the Sony A68 place the cameras among the top in their class? Find out in the latest Best DSLR Camera listing 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 says little about, for example, the shooting experience and imaging performance of the D3100 and the A68 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 why expert reviews 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.		Nikon D3100	5/5	+ +	..	72/100	4.5/5	4.5/5	Aug 2010	599	ebay.com
2.		Sony A68	3/5	..	..	..	4/5	4/5	Nov 2015	699	ebay.com
3.		Nikon D40	..	81/100	..	+ +	o	4.5/5	Nov 2006	499	ebay.com
4.		Nikon D40X	..	79/100	..	+ +	4/5	4/5	Mar 2007	729	ebay.com
5.		Nikon D60	..	80/100	..	+ +	4/5	4.5/5	Jan 2008	629	ebay.com
6.		Nikon D3000	..	+	..	72/100	4/5	4.5/5	Jul 2009	599	ebay.com
7.		Nikon D3200	5/5	+ +	..	73/100	4.5/5	4.5/5	Apr 2012	599	ebay.com
8.		Nikon D5000	..	+ +	..	75/100	4/5	4.5/5	Apr 2009	749	ebay.com
9.		Nikon D5100	5/5	+ +	..	76/100	4.5/5	4.5/5	Apr 2011	749	ebay.com
10.		Nikon D7000	4/5	..	..	80/100	4.5/5	4.5/5	Sep 2010	1,499	ebay.com
11.		Pentax K-S1	4/5	..	..	..	4.5/5	4/5	Aug 2014	749	ebay.com
12.		Sony A58	3/5	..	..	..	4.5/5	4.5/5	Feb 2013	599	ebay.com
13.		Sony A77	5/5	91/100	..	81/100	..	5/5	Aug 2011	1,399	ebay.com
14.		Sony A77 II	4/5	..	..	80/100	4.5/5	5/5	May 2014	1,199	ebay.com
15.		Sony A6000	5/5	+	4.5/5	80/100	4.5/5	5/5	Feb 2014	599	ebay.com
16.		Sony NEX-5N	3/5	+ +	..	79/100	4.5/5	4.5/5	Aug 2011	699	ebay.com
17.		Sony NEX-C3	3/5	+ +	..	74/100	4.5/5	4/5	Jun 2011	599	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The above review scores should be interpreted with care, though. The assessments were made in relation to similar cameras of the same technological generation. Thus, a score needs to be put into the context of the launch date and the launch price of the camera, 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

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