Pentax K-3 vs Sony RX1

The Pentax K-3 and the Sony Cyber-shot DSC-RX1 are two enthusiast cameras that were officially introduced, respectively, in October 2013 and September 2012. The K-3 is a DSLR, while the RX1 is a fixed lens compact. The cameras are based on an APS-C (K-3) and a full frame (RX1) sensor. The Pentax has a resolution of 24.1 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

Pentax K-3		Sony RX1
Digital single lens reflex		Fixed lens compact camera
Pentax K mount lenses		35mm f/2.0
24.1 MP – APS-C sensor		24 MP – Full Frame sensor
1080/60i Video		1080/60p Video
ISO 100-51,200		ISO 100-25,600 (50 - 102,400)
Optical viewfinder		Viewfinder optional
3.2" LCD – 1037k dots		3.0" LCD – 1229k dots
Fixed screen (not touch-sensitive)		Fixed screen (not touch-sensitive)
8.3 shutter flaps per second		5 shutter flaps per second
In-body stabilization		no shake reduction
Weathersealed body		not weather sealed
560 shots per battery charge		270 shots per battery charge
131 x 100 x 77 mm, 800 g		113 x 65 x 70 mm, 482 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Pentax K-3 and the Sony Cyber-shot DSC-RX1? 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 Pentax K-3 and the Sony RX1 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 K-3 can be obtained in two different colors (black, silver), while the RX1 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 RX1 is considerably smaller (44 percent) than the Pentax K-3. It is worth mentioning in this context that the K-3 is splash and dust resistant, while the RX1 does not feature any corresponding weather-sealing.

The above size and weight comparisons are to some extent incomplete and possibly misleading, as the RX1 has a lens built in, whereas the K-3 is an interchangeable lens camera that requires a separate lens. Attaching the latter will add extra weight and bulk to the setup.

Concerning battery life, the K-3 gets 560 shots out of its Pentax D-LI90 battery, while the RX1 can take 270 images on a single charge of its Sony NP-BX1 power pack. The power pack in the RX1 can be charged via the USB port, 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. 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	Street Price
1.		Pentax K-3	131 mm	100 mm	77 mm	800 g	560	Y	Oct 2013	US$ 1 299	ebay.com
2.		Sony RX1	113 mm	65 mm	70 mm	482 g	270	n	Sep 2012	US$ 2 799	ebay.com
3.		Nikon D5300	125 mm	98 mm	76 mm	480 g	600	n	Oct 2013	US$ 799	ebay.com
4.		Nikon D7100	136 mm	107 mm	76 mm	765 g	950	Y	Feb 2013	US$ 1 199	ebay.com
5.		Pentax K-3 II	131 mm	100 mm	77 mm	800 g	720	Y	Apr 2015	US$ 1 099	ebay.com
6.		Pentax K-5	131 mm	97 mm	73 mm	760 g	740	Y	Sep 2010	US$ 1 099	ebay.com
7.		Pentax K-5 II	131 mm	97 mm	73 mm	760 g	740	Y	Sep 2012	US$ 1 099	ebay.com
8.		Pentax K-50	130 mm	97 mm	71 mm	650 g	410	Y	Jun 2013	US$ 599	ebay.com
9.		Pentax K-70	126 mm	93 mm	74 mm	688 g	410	Y	Jun 2016	US$ 649	ebay.com
10.		Pentax KP	132 mm	101 mm	76 mm	703 g	390	Y	Jan 2017	US$ 1 099	ebay.com
11.		Pentax K-S1	121 mm	93 mm	70 mm	558 g	410	n	Aug 2014	US$ 749	ebay.com
12.		Pentax K-S2	123 mm	91 mm	73 mm	678 g	410	Y	Feb 2015	US$ 749	ebay.com
13.		Sony A77	143 mm	104 mm	81 mm	732 g	470	Y	Aug 2011	US$ 1 399	ebay.com
14.		Sony A3000	128 mm	91 mm	85 mm	411 g	470	n	Aug 2013	US$ 329	ebay.com
15.		Sony NEX-7	120 mm	67 mm	43 mm	400 g	430	n	Aug 2011	US$ 1 349	ebay.com
16.		Sony RX1R	113 mm	65 mm	70 mm	482 g	270	n	Jun 2013	US$ 2 799	ebay.com
17.		Sony RX1R II	113 mm	65 mm	72 mm	507 g	220	n	Oct 2015	US$ 3 299	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 manufacturer’s suggested retail prices give an idea on the placement of the camera in the maker’s lineup and the broader market. 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. Then, after the new model is out, very good deals can frequently be found on the pre-owned market.

Sensor comparison

The size of the imaging sensor is a crucial determinant 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. 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 K-3 features an APS-C sensor and the Sony RX1 a full frame sensor. The sensor area in the RX1 is 132 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.5 and 1.0. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

Despite having a smaller sensor, the Pentax K-3 offers a higher resolution of 24.1 megapixels, compared with 24 MP of the Sony RX1. 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 3.90μm versus 5.96μm for the RX1). However, it should be noted that the K-3 is a somewhat more recent model (by 1 year) than the RX1, and its sensor might have benefitted from technological advances during this time that partly offset its pixel-size disadvantage. Coming back to sensor resolution, it should be mentioned that the K-3 has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

The Pentax K-3 has a native sensitivity range from ISO 100 to ISO 51200. The corresponding ISO settings for the Sony Cyber-shot DSC-RX1 are ISO 100 to ISO 25600, with the possibility to increase the ISO range to 50-102400.

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 RX1 offers substantially better image quality than the K-3 (overall score 13 points higher). The advantage is based on 1.4 bits higher color depth, 0.9 EV in additional dynamic range, and 1.1 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.		Pentax K-3	APS-C	24.1	6016	4000	1080/60i	23.7	13.4	1216	80
2.		Sony RX1	Full Frame	24.0	6000	4000	1080/60p	25.1	14.3	2534	93
3.		Nikon D5300	APS-C	24.0	6000	4000	1080/60p	24.0	13.9	1338	83
4.		Nikon D7100	APS-C	24.0	6000	4000	1080/60p	24.2	13.7	1256	83
5.		Pentax K-3 II	APS-C	24.1	6016	4000	1080/60i	23.6	13.6	1106	80
6.		Pentax K-5	APS-C	16.1	4928	3264	1080/25p	23.7	14.1	1162	82
7.		Pentax K-5 II	APS-C	16.1	4928	3264	1080/25p	23.8	14.1	1235	82
8.		Pentax K-50	APS-C	16.1	4928	3264	1080/30p	23.7	13.0	1120	79
9.		Pentax K-70	APS-C	24.0	6000	4000	1080/60i	23.8	13.1	1639	80
10.		Pentax KP	APS-C	24.1	6016	4000	1080/60i	23.9	13.2	1699	81
11.		Pentax K-S1	APS-C	20.0	5472	3648	1080/30p	23.5	13.0	1061	78
12.		Pentax K-S2	APS-C	20.0	5472	3648	1080/30p	23.6	12.9	1514	79
13.		Sony A77	APS-C	24.0	6000	4000	1080/60p	24.0	13.2	801	78
14.		Sony A3000	APS-C	19.8	5456	3632	1080/60i	23.7	12.8	1068	78
15.		Sony NEX-7	APS-C	24.0	6000	4000	1080/60i	24.1	13.4	1016	81
16.		Sony RX1R	Full Frame	24.0	6000	4000	1080/60p	25.0	13.6	2537	91
17.		Sony RX1R II	Full Frame	42.2	7952	5304	1080/60p	25.8	13.9	3204	97
Note: DXO values in italics represent estimates based on sensor size and age.

Many modern cameras cannot only take still pictures, but also record videos. The two cameras under consideration both have sensors whose read-out speed is fast enough to capture moving pictures, but the RX1 provides a faster frame rate than the K-3. It can shoot movie footage at 1080/60p, while the Pentax is limited to 1080/60i.

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. For example, the K-3 has an optical viewfinder, which can be very useful when shooting in bright sunlight. In contrast, the RX1 relies on live view and the rear LCD for framing. That said, the RX1 can be equipped with an optional viewfinder – the FDA-EV1MK. The adjacent table lists some of the other core features of the Pentax K-3 and Sony RX1 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 K-3	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	Y	Y
2.		Sony RX1	optional	n	3.0 / 1229	fixed	n	1/4000s	5.0/s	Y	n
3.		Nikon D5300	optical	n	3.2 / 1037	swivel	n	1/4000s	5.0/s	Y	n
4.		Nikon D7100	optical	Y	3.2 / 1229	fixed	n	1/8000s	6.0/s	Y	n
5.		Pentax K-3 II	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	n	Y
6.		Pentax K-5	optical	Y	3.0 / 921	fixed	n	1/8000s	7.0/s	Y	Y
7.		Pentax K-5 II	optical	Y	3.0 / 921	fixed	n	1/8000s	7.0/s	Y	Y
8.		Pentax K-50	optical	n	3.0 / 921	fixed	n	1/6000s	6.0/s	Y	Y
9.		Pentax K-70	optical	n	3.0 / 921	swivel	n	1/6000s	6.0/s	Y	Y
10.		Pentax KP	optical	n	3.0 / 921	tilting	n	1/6000s	7.0/s	Y	Y
11.		Pentax K-S1	optical	n	3.0 / 921	fixed	n	1/6000s	5.4/s	Y	Y
12.		Pentax K-S2	optical	n	3.0 / 921	swivel	n	1/6000s	5.4/s	Y	Y
13.		Sony A77	2359	Y	3.0 / 921	full-flex	n	1/8000s	12.0/s	Y	Y
14.		Sony A3000	202	n	3.0 / 230	fixed	n	1/4000s	2.5/s	Y	n
15.		Sony NEX-7	2359	n	3.0 / 921	tilting	n	1/4000s	10.0/s	Y	n
16.		Sony RX1R	optional	n	3.0 / 1229	fixed	n	1/4000s	5.0/s	Y	n
17.		Sony RX1R II	2360	n	3.0 / 1229	tilting	n	1/4000s	5.0/s	n	n
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that is present on the K-3, but is missing on the RX1 is a top-level LCD. While being, of course, smaller than the rear screen, the control panel conveys some of the essential shooting information and can be convenient for quick and easy settings verification.

The Pentax K-3 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 K-3 writes its imaging data to SDXC cards, while the RX1 uses SDXC or Memory Stick PRO Duo cards. The K-3 features dual card slots, which can be very useful in case a memory card fails. In contrast, the RX1 only has one slot. The K-3 supports UHS-I cards (Ultra High Speed data transfer of up to 104 MB/s), while the RX1 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 Pentax K-3 and Sony Cyber-shot DSC-RX1 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 K-3	Y	mono / mono	Y	Y	mini	3.0	-	-	-
2.		Sony RX1	Y	stereo / mono	Y	-	mini	2.0	-	-	-
3.		Nikon D5300	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
4.		Nikon D7100	Y	stereo / mono	Y	Y	mini	2.0	-	-	-
5.		Pentax K-3 II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
6.		Pentax K-5	Y	stereo / mono	Y	-	mini	2.0	-	-	-
7.		Pentax K-5 II	Y	stereo / mono	Y	-	mini	2.0	-	-	-
8.		Pentax K-50	Y	mono / mono	-	-	micro	2.0	-	-	-
9.		Pentax K-70	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
10.		Pentax KP	Y	stereo / mono	Y	-	-	2.0	Y	-	-
11.		Pentax K-S1	Y	stereo / mono	-	-	micro	2.0	-	-	-
12.		Pentax K-S2	Y	mono / mono	Y	-	micro	2.0	Y	Y	-
13.		Sony A77	Y	stereo / mono	Y	-	mini	2.0	-	-	-
14.		Sony A3000	Y	stereo / mono	-	-	mini	2.0	-	-	-
15.		Sony NEX-7	Y	stereo / mono	Y	-	mini	2.0	-	-	-
16.		Sony RX1R	Y	stereo / mono	Y	-	mini	2.0	-	-	-
17.		Sony RX1R II	Y	stereo / mono	Y	-	micro	2.0	Y	Y	-

Studio photographers will appreciate that the Pentax K-3 (unlike the RX1) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the K-3 and the RX1 have been discontinued, but can regularly be found used on ebay. The RX1 was replaced by the Sony RX1R, while the K-3 was followed by the Pentax K-3 II. Further information on the features and operation of the K-3 and RX1 can be found, respectively, in the Pentax K-3 Manual (free pdf) or the online Sony RX1 Manual.

Review summary

So how do things add up? Which of the two cameras – the Pentax K-3 or the Sony RX1 – has the upper hand? Is one clearly better than the other? A synthesis of the relative strong points of each of the models is listed below.

Arguments in favor of the Pentax K-3:

• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• Better sound control: Has a headphone port that enables audio monitoring while recording.
• Easier framing: Has an optical viewfinder for image composition and settings control.
• Easier setting verification: Features an LCD display on top to control shooting parameters.
• Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
• Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
• Faster burst: Shoots at higher frequency (8.3 vs 5 flaps/sec) to capture the decisive moment.
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• More flexible: Can take a variety of interchangeable lenses, including specialty optics.
• Longer lasting: Can take more shots (560 versus 270) 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.
• Faster data transfer: Supports a more advanced USB protocol (3.0 vs 2.0).
• Better studio light control: Has a PC Sync socket to connect to professional strobe lights.
• Greater peace of mind: Features a second card slot as a backup in case of memory card failure.
• Faster buffer clearing: Has an SD card interface that supports the UHS-I standard.
• More modern: Is somewhat more recent (announced 1 year after the RX1).

Advantages of the Sony Cyber-shot DSC-RX1:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Better image quality: Scores substantially higher (13 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (1.4 bits more color depth).
• More dynamic range: Captures a broader range of light and dark details (0.9 EV of extra DR).
• Better low-light sensitivity: Can shoot in dim conditions (1.1 stops ISO advantage).
• Better video: Provides higher movie framerates (1080/60p versus 1080/60i).
• More detailed LCD: Has a higher resolution rear screen (1229k vs 1037k dots).
• Ready to shoot: Comes with an integrated lens, while the K-3 requires a separate lens.
• More compact: Is smaller (113x65mm vs 131x100mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight even though it has a lens built in (unlike the K-3).
• Easier travel charging: Can be conveniently charged via its USB port.
• More heavily discounted: Has been on the market for longer (launched in September 2012).

If the count of individual advantages (bullet points above) is taken as a guide, the K-3 is the clear winner of the match-up (17 : 12 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 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 K-3 and the Sony RX1 place the cameras among the top in their class? Find out in the latest Best DSLR Camera and Best Prime Lens Compact Camera listings 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 K-3 and the RX1 in practical situations. 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 expert reviews 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	Street Price
1.		Pentax K-3	4/5	..	..	83/100	5/5	5/5	Oct 2013	US$ 1 299	ebay.com
2.		Sony RX1	5/5	..	..	79/100	4/5	4.5/5	Sep 2012	US$ 2 799	ebay.com
3.		Nikon D5300	4/5	+ +	..	79/100	4.5/5	4.5/5	Oct 2013	US$ 799	ebay.com
4.		Nikon D7100	5/5	+ +	..	85/100	4.5/5	4.5/5	Feb 2013	US$ 1 199	ebay.com
5.		Pentax K-3 II	4.5/5	..	..	..	5/5	5/5	Apr 2015	US$ 1 099	ebay.com
6.		Pentax K-5	4/5	..	..	83/100	5/5	4.5/5	Sep 2010	US$ 1 099	ebay.com
7.		Pentax K-5 II	5/5	..	..	80/100	5/5	4.5/5	Sep 2012	US$ 1 099	ebay.com
8.		Pentax K-50	5/5	..	..	..	5/5	4.5/5	Jun 2013	US$ 599	ebay.com
9.		Pentax K-70	4.5/5	..	4/5	79/100	4.5/5	4.5/5	Jun 2016	US$ 649	ebay.com
10.		Pentax KP	4/5	..	3/5	82/100	5/5	4.5/5	Jan 2017	US$ 1 099	ebay.com
11.		Pentax K-S1	4/5	..	..	..	4.5/5	4/5	Aug 2014	US$ 749	ebay.com
12.		Pentax K-S2	4.5/5	..	..	..	5/5	4.5/5	Feb 2015	US$ 749	ebay.com
13.		Sony A77	5/5	91/100	..	81/100	..	5/5	Aug 2011	US$ 1 399	ebay.com
14.		Sony A3000	3/5	+	..	..	4/5	4/5	Aug 2013	US$ 329	ebay.com
15.		Sony NEX-7	5/5	+ +	..	81/100	4.5/5	5/5	Aug 2011	US$ 1 349	ebay.com
16.		Sony RX1R	5/5	..	..	..	4/5	4.5/5	Jun 2013	US$ 2 799	ebay.com
17.		Sony RX1R II	5/5	..	..	82/100	..	4.5/5	Oct 2015	US$ 3 299	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 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.

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Other camera comparisons

Did this review help to inform your camera decision process? In case you are interested in seeing how other cameras pair up, just make your choice using the following search menu. As an alternative, you can also directly jump to any one of the listed comparisons that were previously generated by the CAM-parator tool.

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