Pentax Q vs Nikon D3100

The Pentax Q and the Nikon D3100 are two digital cameras that were revealed to the public, respectively, in June 2011 and August 2010. The Pentax Q is a mirrorless interchangeable lens camera, while the D3100 is a DSLR. The cameras are based on a 1/2.3-inch (Pentax Q) and an APS-C (D3100) sensor. The Pentax has a resolution of 12 megapixels, whereas the Nikon provides 14.2 MP.

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

Headline Specifications

Pentax Q		Nikon D3100
Mirrorless system camera		Digital single lens reflex
Pentax Q mount lenses		Nikon F mount lenses
12 MP – 1/2.3" sensor		14.2 MP – APS-C sensor
1080/30p Video		1080/24p Video
ISO 125-6,400		ISO 100-3,200 (100 - 12,800)
Viewfinder optional		Optical viewfinder
3.0" LCD – 460k dots		3.0" LCD – 230k dots
Fixed screen (not touch-sensitive)		Fixed screen (not touch-sensitive)
1.5 shutter flaps per second		3 shutter flaps per second
In-body stabilization		Lens stabilization only
230 shots per battery charge		550 shots per battery charge
98 x 57 x 31 mm, 180 g		124 x 96 x 75 mm, 505 g

Check Pentax Q offers at
ebay.com
Check D3100 offers at
ebay.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Pentax Q and the Nikon D3100? 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 Pentax Q and the Nikon D3100 is provided 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 Pentax Q can be obtained in two different colors (black, white), while the D3100 is also available in two color-versions, but different ones (black, red).

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Nikon D3100 is considerably larger (113 percent) than the Pentax Q. Moreover, the D3100 is substantially heavier (181 percent) than the Pentax Q. In this context, it is worth noting that neither the Pentax Q nor the D3100 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.

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.		Pentax Q	98 mm	57 mm	31 mm	180 g	230	n	Jun 2011	649	ebay.com
2.		Nikon D3100	124 mm	96 mm	75 mm	505 g	550	n	Aug 2010	599	ebay.com
3.		Fujifilm X10	117 mm	70 mm	57 mm	350 g	270	n	Sep 2011	599	ebay.com
4.		Nikon D3200	125 mm	96 mm	77 mm	505 g	540	n	Apr 2012	599	ebay.com
5.		Nikon D5100	128 mm	97 mm	79 mm	560 g	660	n	Apr 2011	749	ebay.com
6.		Nikon D7000	132 mm	105 mm	77 mm	780 g	1050	Y	Sep 2010	1,499	ebay.com
7.		Nikon D3000	126 mm	97 mm	64 mm	536 g	500	n	Jul 2009	599	ebay.com
8.		Nikon D5000	127 mm	104 mm	80 mm	590 g	510	n	Apr 2009	749	ebay.com
9.		Olympus XZ-2	113 mm	65 mm	48 mm	346 g	340	n	Sep 2012	599	ebay.com
10.		Olympus E-P3	122 mm	69 mm	34 mm	369 g	330	n	Jun 2011	799	ebay.com
11.		Olympus E-PL2	114 mm	72 mm	42 mm	362 g	280	n	Jan 2011	599	ebay.com
12.		Olympus E-PL3	110 mm	64 mm	37 mm	313 g	300	n	Jun 2011	599	ebay.com
13.		Olympus E-PL1	115 mm	72 mm	42 mm	334 g	290	n	Feb 2010	599	ebay.com
14.		Olympus E-620	130 mm	94 mm	60 mm	521 g	500	n	Feb 2009	699	ebay.com
15.		Panasonic GF3	108 mm	67 mm	32 mm	264 g	300	n	Jun 2011	549	ebay.com
16.		Panasonic G2	124 mm	84 mm	74 mm	428 g	360	n	Mar 2010	599	ebay.com
17.		Panasonic GF2	113 mm	68 mm	33 mm	310 g	300	n	Nov 2010	549	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 obviously take relative prices into account. 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. The D3100 was somewhat cheaper (by 8 percent) than the Pentax Q at launch, but both cameras fall into the same price category. 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. 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 Pentax Q features a 1/2.3-inch sensor and the Nikon D3100 an APS-C sensor. The sensor area in the D3100 is 1171 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 5.6 and 1.5. The sensor in the Pentax Q has a native 4:3 aspect ratio, while the one in the D3100 offers a 3:2 aspect.

With 14.2MP, the D3100 offers a higher resolution than the Pentax Q (12MP), but the D3100 nevertheless has larger individual pixels (pixel pitch of 5.01μm versus 1.53μm for the Pentax Q) due to its larger sensor. However, the Pentax Q is a somewhat more recent model (by 10 months) than the D3100, and its sensor might have benefitted from technological advances during this time that enhance the light gathering capacity of its pixel-units.

The resolution advantage of the Nikon D3100 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the D3100 for good quality output (200 dots per inch) amounts to 23 x 15.4 inches or 58.5 x 39 cm, for very good quality (250 dpi) 18.4 x 12.3 inches or 46.8 x 31.2 cm, and for excellent quality (300 dpi) 15.4 x 10.2 inches or 39 x 26 cm. The corresponding values for the Pentax Q are 20 x 15 inches or 50.8 x 38.1 cm for good quality, 16 x 12 inches or 40.6 x 30.5 cm for very good quality, and 13.3 x 10 inches or 33.9 x 25.4 cm for excellent quality prints.

The Pentax Q has a native sensitivity range from ISO 125 to ISO 6400. The corresponding ISO settings for the Nikon D3100 are ISO 100 to ISO 3200, with the possibility to increase the ISO range to 100-12800.

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 determines an overall sensor rating, as well as sub-scores for low-light sensitivity ("DXO Sports"), dynamic range ("DXO Landscape"), and color depth ("DXO Portrait"). Of the two cameras under consideration, the D3100 offers substantially better image quality than the Pentax Q (overall score 20 points higher). The advantage is based on 2.3 bits higher color depth, 0.2 EV in additional dynamic range, and 2.3 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.		Pentax Q	1/2.3	12.0	4000	3000	1080/30p	20.2	11.1	189	47
2.		Nikon D3100	APS-C	14.2	4608	3072	1080/24p	22.5	11.3	919	67
3.		Fujifilm X10	2/3	12.0	4000	3000	1080/30p	20.5	11.3	245	50
4.		Nikon D3200	APS-C	24.1	6016	4000	1080/30p	24.1	13.2	1131	81
5.		Nikon D5100	APS-C	16.1	4928	3264	1080/30p	23.5	13.6	1183	80
6.		Nikon D7000	APS-C	16.1	4928	3264	1080/24p	23.5	13.9	1167	80
7.		Nikon D3000	APS-C	10.0	3872	2592	none	22.3	11.1	563	62
8.		Nikon D5000	APS-C	12.2	4288	2848	720/24p	22.7	12.5	868	72
9.		Olympus XZ-2	1/1.7	11.8	3968	2976	1080/30p	20.4	11.3	216	49
10.		Olympus E-P3	Four Thirds	12.2	4032	3024	1080/60i	20.8	10.1	536	51
11.		Olympus E-PL2	Four Thirds	12.2	4032	3024	720/30p	21.4	10.2	573	55
12.		Olympus E-PL3	Four Thirds	12.2	4032	3024	1080/60i	20.9	10.3	499	52
13.		Olympus E-PL1	Four Thirds	12.2	4032	3024	720/30p	21.5	10.1	487	54
14.		Olympus E-620	Four Thirds	12.2	4032	3024	none	21.3	10.3	536	55
15.		Panasonic GF3	Four Thirds	12.0	4000	3000	1080/60i	20.6	10.1	459	50
16.		Panasonic G2	Four Thirds	12.0	4000	3000	720/30p	21.2	10.3	493	53
17.		Panasonic GF2	Four Thirds	12.0	4000	3000	1080/60i	21.2	10.3	506	54

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 Pentax Q provides a higher frame rate than the D3100. It can shoot video footage at 1080/30p, 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 D3100 has an optical viewfinder, which can be very useful when shooting in bright sunlight. In contrast, the Pentax Q relies on live view and the rear LCD for framing. That said, the Pentax Q can be equipped with an optional viewfinder – the O-VF1. The adjacent table lists some of the other core features of the Pentax Q and Nikon D3100 along with similar information for a selection of comparators.

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.		Pentax Q	optional	n	3.0 / 460	fixed	n	1/2000s	1.5/s	Y	Y
2.		Nikon D3100	optical	n	3.0 / 230	fixed	n	1/4000s	3.0/s	Y	n
3.		Fujifilm X10	optical	n	2.8 / 460	fixed	n	1/4000s	10.0/s	Y	Y
4.		Nikon D3200	optical	n	3.0 / 921	fixed	n	1/4000s	4.0/s	Y	n
5.		Nikon D5100	optical	n	3.0 / 921	swivel	n	1/4000s	4.0/s	Y	n
6.		Nikon D7000	optical	Y	3.0 / 921	fixed	n	1/8000s	6.0/s	Y	n
7.		Nikon D3000	optical	n	3.0 / 230	fixed	n	1/4000s	3.0/s	Y	n
8.		Nikon D5000	optical	n	2.7 / 230	full-flex	n	1/4000s	4.0/s	Y	n
9.		Olympus XZ-2	optional	n	3.0 / 920	tilting	Y	1/2000s	5.0/s	Y	Y
10.		Olympus E-P3	optional	n	3.0 / 614	fixed	Y	1/4000s	3.0/s	Y	Y
11.		Olympus E-PL2	optional	n	3.0 / 460	fixed	n	1/4000s	3.0/s	Y	Y
12.		Olympus E-PL3	optional	n	3.0 / 460	tilting	n	1/4000s	5.5/s	n	Y
13.		Olympus E-PL1	optional	n	2.7 / 230	fixed	n	1/2000s	3.0/s	Y	Y
14.		Olympus E-620	optical	n	2.7 / 230	swivel	n	1/4000s	4.0/s	Y	Y
15.		Panasonic GF3	none	n	3.0 / 460	fixed	Y	1/4000s	3.2/s	Y	n
16.		Panasonic G2	1440	n	3.0 / 460	swivel	Y	1/4000s	2.6/s	Y	n
17.		Panasonic GF2	optional	n	3.0 / 460	fixed	Y	1/4000s	2.6/s	Y	n
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that differentiates the Pentax Q and the D3100 is in-body image stabilization (IBIS). The Pentax Q 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 Pentax Q 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 Pentax Q and the D3100 write their files to SDXC 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 Pentax Q and Nikon D3100 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.		Pentax Q	Y	mono / mono	-	-	mini	2.0	-	-	-
2.		Nikon D3100	Y	mono / mono	-	-	mini	2.0	-	-	-
3.		Fujifilm X10	Y	stereo / mono	-	-	mini	2.0	-	-	-
4.		Nikon D3200	Y	mono / mono	Y	-	mini	2.0	-	-	-
5.		Nikon D5100	Y	mono / mono	Y	-	mini	2.0	-	-	-
6.		Nikon D7000	Y	mono / mono	Y	-	mini	2.0	-	-	-
7.		Nikon D3000	Y	- / -	-	-	-	2.0	-	-	-
8.		Nikon D5000	Y	mono / mono	-	-	mini	2.0	-	-	-
9.		Olympus XZ-2	Y	stereo / mono	-	-	mini	2.0	-	-	-
10.		Olympus E-P3	Y	stereo / -	-	-	mini	2.0	-	-	-
11.		Olympus E-PL2	Y	stereo / -	-	-	mini	2.0	-	-	-
12.		Olympus E-PL3	Y	stereo / -	-	-	mini	2.0	-	-	-
13.		Olympus E-PL1	Y	stereo / -	-	-	mini	2.0	-	-	-
14.		Olympus E-620	Y	- / -	-	-	-	2.0	-	-	-
15.		Panasonic GF3	-	stereo / mono	-	-	mini	2.0	-	-	-
16.		Panasonic G2	Y	stereo / mono	-	-	mini	2.0	-	-	-
17.		Panasonic GF2	Y	stereo / mono	-	-	mini	2.0	-	-	-

Both the Pentax Q and the D3100 have been discontinued, but can regularly be found used on ebay. The D3100 was replaced by the Nikon D3200, while the Pentax Q was followed by the Pentax Q10. Further information on the features and operation of the Pentax Q and D3100 can be found, respectively, in the Pentax Q Manual (free pdf) or the online Nikon D3100 Manual.

Review summary

So how do things add up? Is there a clear favorite between the Pentax Q and the Nikon D3100? Which camera is better? Below is a summary of the relative strengths of each of the two contestants.

Arguments in favor of the Pentax Q:

• Better video: Provides higher movie framerates (1080/30p versus 1080/24p).
• More detailed LCD: Has a higher resolution rear screen (460k vs 230k dots).
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• More compact: Is smaller (98x57mm vs 124x96mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 325g or 64 percent) and hence easier to carry around.
• Sharper images: Has hand-shake reducing image stabilization built-in.
• More legacy lens friendly: Can take a broad range of non-native lenses via adapters.
• More modern: Is somewhat more recent (announced 10 months after the D3100).

Advantages of the Nikon D3100:

• More detail: Has more megapixels (14.2 vs 12MP), which boosts linear resolution by 11%.
• Better image quality: Scores substantially higher (20 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (2.3 bits more color depth).
• Better low-light sensitivity: Can shoot in dim conditions (2.3 stops ISO advantage).
• Easier framing: Has an optical viewfinder for image composition and settings control.
• Faster shutter: Has higher mechanical shutter speed (1/4000s vs 1/2000s) to freeze action.
• Faster burst: Shoots at higher frequency (3 vs 1.5 flaps/sec) to capture the decisive moment.
• Longer lasting: Gets more shots (550 versus 230) out of a single battery charge.
• More heavily discounted: Has been on the market for longer (launched in August 2010).

If the count of individual advantages (bullet points above) is taken as a guide, the D3100 comes out slightly ahead of the Pentax Q (9 : 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 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 Pentax Q and the Nikon D3100 place the cameras among the top in their class? Find out in the latest Best Mirrorless Interchangeable Lens Camera and Best DSLR Camera listings 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 incomplete and does no justice, for example, to the way the Pentax Q or the D3100 perform in practice. 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 following table reports the overall ratings of the cameras as published by some of the major 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.		Pentax Q	3/5	..	..	..	4/5	3.5/5	Jun 2011	649	ebay.com
2.		Nikon D3100	5/5	+ +	..	72/100	4.5/5	4.5/5	Aug 2010	599	ebay.com
3.		Fujifilm X10	..	..	..	76/100	4/5	4.5/5	Sep 2011	599	ebay.com
4.		Nikon D3200	5/5	+ +	..	73/100	4.5/5	4.5/5	Apr 2012	599	ebay.com
5.		Nikon D5100	5/5	+ +	..	76/100	4.5/5	4.5/5	Apr 2011	749	ebay.com
6.		Nikon D7000	4/5	..	..	80/100	4.5/5	4.5/5	Sep 2010	1,499	ebay.com
7.		Nikon D3000	..	+	..	72/100	4/5	4.5/5	Jul 2009	599	ebay.com
8.		Nikon D5000	..	+ +	..	75/100	4/5	4.5/5	Apr 2009	749	ebay.com
9.		Olympus XZ-2	4/5	+	..	..	4.5/5	4.5/5	Sep 2012	599	ebay.com
10.		Olympus E-P3	..	83/100	..	74/100	4.5/5	4.5/5	Jun 2011	799	ebay.com
11.		Olympus E-PL2	3/5	83/100	..	71/100	4.5/5	4.5/5	Jan 2011	599	ebay.com
12.		Olympus E-PL3	3/5	+ +	..	72/100	4.5/5	4/5	Jun 2011	599	ebay.com
13.		Olympus E-PL1	..	86/100	..	69/100	4/5	4.5/5	Feb 2010	599	ebay.com
14.		Olympus E-620	3/5	88/100	..	72/100	4.5/5	5/5	Feb 2009	699	ebay.com
15.		Panasonic GF3	3/5	82/100	..	71/100	4.5/5	4/5	Jun 2011	549	ebay.com
16.		Panasonic G2	..	..	..	72/100	4/5	4.5/5	Mar 2010	599	ebay.com
17.		Panasonic GF2	3/5	82/100	..	70/100	4.5/5	4.5/5	Nov 2010	549	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

Care should be taken when interpreting the review scores above, though. The ratings were established in reference to similarly priced cameras that were available in the market at the time of the review. A score, therefore, has to be seen in close connection to the price and market introduction time of the camera, 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.

Check Pentax Q offers at
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Check D3100 offers at
ebay.com

Other camera comparisons

Did this review help to inform your camera decision process? If you would like to see a different side-by-side camera review, just use the search menu below. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored.

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