Pentax K-S1 vs Sony RX0 II

The Pentax K-S1 and the Sony Cyber-shot DSC-RX0II are two digital cameras that were announced, respectively, in August 2014 and March 2019. The K-S1 is a DSLR, while the RX0 II is a fixed lens compact. The cameras are based on an APS-C (K-S1) and an one-inch (RX0 II) sensor. The Pentax has a resolution of 20 megapixels, whereas the Sony provides 15.4 MP.

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

Headline Specifications

Pentax K-S1		Sony RX0 II
Digital single lens reflex		Fixed lens compact camera
Pentax K mount lenses		24mm f/4.0
20 MP – APS-C sensor		15.4 MP – 1" sensor
1080/30p Video		4K/30p Video
ISO 100-51,200		ISO 80-12,800
Optical viewfinder		No viewfinder, LCD framing
3.0" LCD – 921k dots		1.5" LCD – 230k dots
Fixed screen (not touch-sensitive)		Tilting screen (no touchscreen)
5.4 shutter flaps per second		5.5 shutter flaps per second
In-body stabilization		no shake reduction
not weather sealed		Waterproof body (10m)
410 shots per battery charge		240 shots per battery charge
121 x 93 x 70 mm, 558 g		59 x 41 x 35 mm, 132 g

Check K-S1 offers at
ebay.com
Check RX0 II price at
amazon.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Pentax K-S1 and the Sony Cyber-shot DSC-RX0II? 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-S1 and the Sony RX0 II 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 size dimensions are rounded to the nearest millimeter.

The K-S1 can be obtained in four different colors (black, grey, orange, white), while the RX0 II 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 RX0 II is considerably smaller (79 percent) than the Pentax K-S1. It is noteworthy in this context that the RX0 II is splash and dust-proof, while the K-S1 does not feature any corresponding weather-sealing. More than that, the RX0 II is water-proof up to 10m and can, thus, be used for underwater photography.

The above size and weight comparisons are to some extent incomplete and possibly misleading, as the RX0 II has a lens built in, whereas the K-S1 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-S1 gets 410 shots out of its Pentax D-LI109 battery, while the RX0 II can take 240 images on a single charge of its Sony NP-BJ1 power pack. The power pack in the RX0 II 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. If you would like to visualize and compare a different camera combination, you can navigate to the CAM-parator app and make your selection from a broad list of cameras 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 K-S1	121 mm	93 mm	70 mm	558 g	410	n	Aug 2014	749	ebay.com
2.		Sony RX0 II	59 mm	41 mm	35 mm	132 g	240	Y	Mar 2019	699	amazon.com
3.		Canon 750D	132 mm	101 mm	78 mm	555 g	440	n	Feb 2015	749	ebay.com
4.		Canon 760D	132 mm	101 mm	78 mm	565 g	440	n	Feb 2015	649	ebay.com
5.		Nikon D5300	125 mm	98 mm	76 mm	480 g	600	n	Oct 2013	799	ebay.com
6.		Pentax K-S2	123 mm	91 mm	73 mm	678 g	410	Y	Feb 2015	749	ebay.com
7.		Pentax K-3 II	131 mm	100 mm	77 mm	800 g	720	Y	Apr 2015	1,099	ebay.com
8.		Pentax K-50	130 mm	97 mm	71 mm	650 g	410	Y	Jun 2013	599	ebay.com
9.		Pentax K-500	130 mm	97 mm	71 mm	646 g	710	n	Jun 2013	549	ebay.com
10.		Pentax K-3	131 mm	100 mm	77 mm	800 g	560	Y	Oct 2013	1,299	ebay.com
11.		Ricoh WG-60	123 mm	62 mm	30 mm	193 g	300	Y	Oct 2018	279	ebay.com
12.		Sony HX99	102 mm	58 mm	36 mm	242 g	370	n	Aug 2018	449	ebay.com
13.		Sony HX95	102 mm	58 mm	36 mm	242 g	370	n	Aug 2018	429	ebay.com
14.		Sony WX800	102 mm	58 mm	36 mm	233 g	370	n	Oct 2018	399	ebay.com
15.		Sony RX0	59 mm	41 mm	30 mm	110 g	240	Y	Aug 2017	699	ebay.com
16.		Sony A68	143 mm	104 mm	81 mm	610 g	540	n	Nov 2015	699	ebay.com
17.		Sony A58	129 mm	95 mm	78 mm	492 g	690	n	Feb 2013	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 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 RX0 II was launched at a lower price than the K-S1, despite having a lens built in. 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 tend to have larger individual pixels that provide better low-light sensitivity, wider dynamic range, and richer color-depth than smaller pixel-units 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 tend to be more expensive and lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Pentax K-S1 features an APS-C sensor and the Sony RX0 II an one-inch sensor. The sensor area in the RX0 II 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 20MP, the K-S1 offers a higher resolution than the RX0 II (15.4MP), but the K-S1 nevertheless has larger individual pixels (pixel pitch of 4.28μm versus 2.74μm for the RX0 II) due to its larger sensor. However, the RX0 II is a much more recent model (by 4 years and 6 months) than the K-S1, and its sensor will have benefitted from technological advances during this time that further enhance the light gathering capacity of its pixels. Coming back to sensor resolution, it should be mentioned that the K-S1 has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

The resolution advantage of the Pentax K-S1 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the K-S1 for good quality output (200 dots per inch) amounts to 27.4 x 18.2 inches or 69.5 x 46.3 cm, for very good quality (250 dpi) 21.9 x 14.6 inches or 55.6 x 37.1 cm, and for excellent quality (300 dpi) 18.2 x 12.2 inches or 46.3 x 30.9 cm. The corresponding values for the Sony RX0 II are 24 x 16 inches or 61 x 40.6 cm for good quality, 19.2 x 12.8 inches or 48.8 x 32.5 cm for very good quality, and 16 x 10.7 inches or 40.6 x 27.1 cm for excellent quality prints.

The Pentax K-S1 has a native sensitivity range from ISO 100 to ISO 51200. The corresponding ISO settings for the Sony Cyber-shot DSC-RX0II are ISO 80 to ISO 12800 (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.

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"). 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 K-S1	APS-C	20.0	5472	3648	1080/30p	23.5	13.0	1061	78
2.		Sony RX0 II	1-inch	15.4	4800	3200	4K/30p	22.1	12.4	555	65
3.		Canon 750D	APS-C	24.0	6000	4000	1080/30p	22.7	12.0	919	71
4.		Canon 760D	APS-C	24.0	6000	4000	1080/30p	22.6	12.0	915	70
5.		Nikon D5300	APS-C	24.0	6000	4000	1080/60p	24.0	13.9	1338	83
6.		Pentax K-S2	APS-C	20.0	5472	3648	1080/30p	23.6	12.9	1514	79
7.		Pentax K-3 II	APS-C	24.1	6016	4000	1080/60i	23.6	13.6	1106	80
8.		Pentax K-50	APS-C	16.1	4928	3264	1080/30p	23.7	13.0	1120	79
9.		Pentax K-500	APS-C	16.1	4928	3264	1080/30p	23.7	13.1	1087	79
10.		Pentax K-3	APS-C	24.1	6016	4000	1080/60i	23.7	13.4	1216	80
11.		Ricoh WG-60	1/2.3	15.9	4608	3456	1080/60p	20.6	12.2	1072	51
12.		Sony HX99	1/2.3	18.0	4896	3672	4K/30p	20.6	12.1	1058	51
13.		Sony HX95	1/2.3	18.0	4896	3672	4K/30p	20.6	12.1	1057	51
14.		Sony WX800	1/2.3	18.0	4896	3672	4K/30p	20.6	12.2	1070	51
15.		Sony RX0	1-inch	15.4	4800	3200	1080/60p	22.4	12.4	548	68
16.		Sony A68	APS-C	24.0	6000	4000	1080/60i	24.1	13.5	701	79
17.		Sony A58	APS-C	19.8	5456	3632	1080/60i	23.3	12.5	753	74
Note: DXO values in italics represent estimates based on sensor size and age.

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 RX0 II provides a better video resolution than the K-S1. It can shoot movie footage at 4K/30p, while the Pentax is limited to 1080/30p.

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. For example, the K-S1 has an optical viewfinder, which can be very useful when shooting in bright sunlight. In contrast, the RX0 II relies on live view and the rear LCD for framing. The adjacent table lists some of the other core features of the Pentax K-S1 and Sony RX0 II 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-S1	optical	n	3.0 / 921	fixed	n	1/6000s	5.4/s	Y	Y
2.		Sony RX0 II	none	n	1.5 / 230	tilting	n	..	5.5/s	n	n
3.		Canon 750D	optical	n	3.0 / 1040	swivel	Y	1/4000s	5.0/s	Y	n
4.		Canon 760D	optical	Y	3.0 / 1040	swivel	Y	1/4000s	5.0/s	Y	n
5.		Nikon D5300	optical	n	3.2 / 1037	swivel	n	1/4000s	5.0/s	Y	n
6.		Pentax K-S2	optical	n	3.0 / 921	swivel	n	1/6000s	5.4/s	Y	Y
7.		Pentax K-3 II	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	n	Y
8.		Pentax K-50	optical	n	3.0 / 921	fixed	n	1/6000s	6.0/s	Y	Y
9.		Pentax K-500	optical	n	3.0 / 921	fixed	n	1/6000s	6.0/s	Y	Y
10.		Pentax K-3	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	Y	Y
11.		Ricoh WG-60	none	n	2.7 / 230	fixed	n	1/4000s	8.0/s	Y	n
12.		Sony HX99	638	n	3.0 / 922	tilting	Y	1/2000s	10.0/s	Y	Y
13.		Sony HX95	638	n	3.0 / 922	tilting	n	1/2000s	10.0/s	Y	Y
14.		Sony WX800	none	n	3.0 / 922	tilting	Y	1/2000s	10.0/s	Y	Y
15.		Sony RX0	none	n	1.5 / 230	fixed	n	..	5.5/s	n	n
16.		Sony A68	1440	Y	2.7 / 460	tilting	n	1/4000s	8.0/s	Y	Y
17.		Sony A58	1440	n	2.7 / 460	tilting	n	1/4000s	5.0/s	Y	Y
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One difference between the cameras concerns the presence of an on-board flash. The K-S1 has one, while the RX0 II does not. While the built-in flash of the K-S1 is not very powerful, it can at times be useful as a fill-in light.

The reported shutter speed information refers to the use of the mechanical shutter. Yet, some cameras only have an electronic shutter, while others have an electronic shutter in addition to a mechanical one. In fact, the RX0 II only has electronic shutter, which makes completely silent shooting possible. However, this mode is less suitable for photographing moving objects (risk of rolling shutter) or shooting under artificial light sources (risk of flickering).

The K-S1 writes its imaging data to SDXC cards, while the RX0 II uses micro SDXC or Memory Stick Micro 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 Pentax K-S1 and Sony Cyber-shot DSC-RX0II 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-S1	Y	stereo / mono	-	-	micro	2.0	-	-	-
2.		Sony RX0 II	-	stereo / mono	Y	-	micro	2.0	Y	-	Y
3.		Canon 750D	Y	stereo / mono	Y	-	mini	2.0	Y	Y	-
4.		Canon 760D	Y	stereo / mono	Y	-	mini	2.0	Y	Y	-
5.		Nikon D5300	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
6.		Pentax K-S2	Y	mono / mono	Y	-	micro	2.0	Y	Y	-
7.		Pentax K-3 II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
8.		Pentax K-50	Y	mono / mono	-	-	micro	2.0	-	-	-
9.		Pentax K-500	Y	mono / mono	-	-	-	2.0	-	-	-
10.		Pentax K-3	Y	mono / mono	Y	Y	mini	3.0	-	-	-
11.		Ricoh WG-60	-	mono / mono	-	-	micro	2.0	-	-	-
12.		Sony HX99	-	stereo / mono	-	-	micro	2.0	Y	Y	Y
13.		Sony HX95	-	stereo / mono	-	-	micro	2.0	Y	Y	Y
14.		Sony WX800	-	stereo / mono	-	-	micro	2.0	Y	Y	-
15.		Sony RX0	-	stereo / mono	Y	-	micro	2.0	Y	-	Y
16.		Sony A68	Y	stereo / mono	Y	-	micro	2.0	-	-	-
17.		Sony A58	Y	stereo / mono	Y	-	mini	2.0	-	-	-

It is notable that the K-S1 has a hotshoe, while the RX0 II does not. This socket makes it possible to easily attach optional accessories, such as an external flash gun.

The RX0 II is a recent model that features in the current product line-up of Sony. In contrast, the K-S1 has been discontinued (but can be found pre-owned on ebay). As a replacement in the same line of cameras, the K-S1 was succeeded by the Pentax K-S2. Further information on the features and operation of the K-S1 and RX0 II can be found, respectively, in the Pentax K-S1 Manual (free pdf) or the online Sony RX0 II Manual.

Review summary

So what is the bottom line? Is the Pentax K-S1 better than the Sony RX0 II or vice versa? The listing below highlights the relative strengths of the two models.

Arguments in favor of the Pentax K-S1:

• More detail: Offers more megapixels (20 vs 15.4MP) with a 14% higher linear resolution.
• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• Easier framing: Has an optical viewfinder for image composition and settings control.
• Larger screen: Has a bigger rear LCD (3.0" vs 1.5") for image review and settings control.
• More detailed LCD: Has a higher resolution rear screen (921k vs 230k dots).
• More flexible: Can take a variety of interchangeable lenses, including specialty optics.
• Longer lasting: Can take more shots (410 versus 240) on a single battery charge.
• Sharper images: Has hand-shake reducing image stabilization built-in.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• 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 August 2014).

Advantages of the Sony Cyber-shot DSC-RX0II:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Better video: Provides higher definition movie capture (4K/30p vs 1080/30p).
• Better sound: Can connect to an external microphone for higher quality sound recording.
• More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
• More selfie-friendly: Has an articulated screen that can be turned to be front-facing.
• Less disturbing: Has an electronic shutter option for completely silent shooting.
• Ready to shoot: Comes with an integrated lens, while the K-S1 requires a separate lens.
• More compact: Is smaller (59x41mm vs 121x93mm) 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-S1).
• Easier travel charging: Can be conveniently charged via its USB port.
• Better sealing: Is splash and dust sealed for shooting in inclement weather conditions.
• Water-proof: Is rugged and sealed and can thus be used for underwater photography (up to 10m).
• Easier file upload: Has wifi built in for automatic backup or image transfer to the web.
• Easier wireless transfer: Supports Bluetooth for image sharing without cables.
• More affordable: Was introduced at a lower price, despite coming with a built-in lens.
• More modern: Reflects 4 years and 6 months of technical progress since the K-S1 launch.

If the count of relative strengths (bullet points above) is taken as a measure, the RX0 II is the clear winner of the contest (16 : 11 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 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 Pentax K-S1 and the Sony RX0 II 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 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 K-S1 or the RX0 II. At times, user reviews, such as those published at amazon, address these issues in a useful manner, but such feedback is on many occasions incomplete, inconsistent, and unreliable.

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 (USD)	Street Price
1.		Pentax K-S1	4/5	..	..	..	4.5/5	4/5	Aug 2014	749	ebay.com
2.		Sony RX0 II	..	..	..	..	3.5/5	4/5	Mar 2019	699	amazon.com
3.		Canon 750D	5/5	..	..	75/100	4.5/5	4.5/5	Feb 2015	749	ebay.com
4.		Canon 760D	5/5	+	..	77/100	4.5/5	4.5/5	Feb 2015	649	ebay.com
5.		Nikon D5300	4/5	+ +	..	79/100	4.5/5	4.5/5	Oct 2013	799	ebay.com
6.		Pentax K-S2	4.5/5	..	..	..	5/5	4.5/5	Feb 2015	749	ebay.com
7.		Pentax K-3 II	4.5/5	..	..	..	5/5	5/5	Apr 2015	1,099	ebay.com
8.		Pentax K-50	5/5	..	..	..	5/5	4.5/5	Jun 2013	599	ebay.com
9.		Pentax K-500	..	..	..	..	4.5/5	4.5/5	Jun 2013	549	ebay.com
10.		Pentax K-3	4/5	..	..	83/100	5/5	5/5	Oct 2013	1,299	ebay.com
11.		Ricoh WG-60	..	..	..	..	..	..	Oct 2018	279	ebay.com
12.		Sony HX99	..	..	..	..	4/5	4.5/5	Aug 2018	449	ebay.com
13.		Sony HX95	..	..	..	..	..	..	Aug 2018	429	ebay.com
14.		Sony WX800	..	..	..	..	..	..	Oct 2018	399	ebay.com
15.		Sony RX0	..	..	..	..	3.5/5	4/5	Aug 2017	699	ebay.com
16.		Sony A68	3/5	..	..	..	4/5	4/5	Nov 2015	699	ebay.com
17.		Sony A58	3/5	..	..	..	4.5/5	4.5/5	Feb 2013	599	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The above review scores should be interpreted 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. Thus, a score needs to be put into the context of the launch date and the launch price of the camera, and comparing ratings of very distinct cameras or ones that are far apart in terms of their release date 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 K-S1 offers at
ebay.com
Check RX0 II price at
amazon.com

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 a corresponding selection in the search boxes 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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Check K-S1 offers at
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Check RX0 II price at
amazon.com

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