Pentax K-S1 vs Sony RX10

The Pentax K-S1 and the Sony Cyber-shot DSC-RX10 are two digital cameras that were revealed to the public, respectively, in August 2014 and October 2013. The K-S1 is a DSLR, while the RX10 is a fixed lens compact. The cameras are based on an APS-C (K-S1) and an one-inch (RX10) sensor. Both cameras offer a resolution of 20 megapixels.

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 RX10
Digital single lens reflex		Fixed lens compact camera
Pentax K mount lenses		24-200mm f/2.8
20 MP – APS-C sensor		20 MP – 1" sensor
1080/30p Video		1080/60p Video
ISO 100-51,200		ISO 125-12,800 (80 - 25,600)
Optical viewfinder		Electronic viewfinder (1440k dots)
3.0" LCD – 921k dots		3.0" LCD – 1229k dots
Fixed screen (not touch-sensitive)		Tilting screen (no touchscreen)
5.4 shutter flaps per second		10 shutter flaps per second
In-body stabilization		Lens-based stabilization
not weather sealed		Weathersealed body
410 shots per battery charge		420 shots per battery charge
121 x 93 x 70 mm, 558 g		129 x 88 x 102 mm, 813 g

Check K-S1 offers at
ebay.com
Check RX10 offers at
ebay.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-RX10? 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 Pentax K-S1 and the Sony RX10. 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-S1 can be obtained in four different colors (black, grey, orange, white), while the RX10 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 Pentax K-S1 and the Sony RX10 are of equal size. It is noteworthy in this context that the RX10 is splash and dust-proof, while the K-S1 does not feature any corresponding weather-sealing.

The above size and weight comparisons are to some extent incomplete and possibly misleading, as the RX10 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 RX10 can take 420 images on a single charge of its Sony NP-FW50 power pack. The power pack in the RX10 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	Street Price
1.		Pentax K-S1	121 mm	93 mm	70 mm	558 g	410	n	Aug 2014	US$ 749	ebay.com
2.		Sony RX10	129 mm	88 mm	102 mm	813 g	420	Y	Oct 2013	US$ 1 299	ebay.com
3.		Canon 70D	139 mm	104 mm	79 mm	755 g	920	Y	Jul 2013	US$ 1 199	ebay.com
4.		Canon 80D	139 mm	105 mm	79 mm	730 g	960	Y	Feb 2016	US$ 1 199	ebay.com
5.		Canon 750D	132 mm	101 mm	78 mm	555 g	440	n	Feb 2015	US$ 749	ebay.com
6.		Canon 760D	132 mm	101 mm	78 mm	565 g	440	n	Feb 2015	US$ 649	ebay.com
7.		Nikon D5300	125 mm	98 mm	76 mm	480 g	600	n	Oct 2013	US$ 799	ebay.com
8.		Nikon D7100	136 mm	107 mm	76 mm	765 g	950	Y	Feb 2013	US$ 1 199	ebay.com
9.		Pentax K-3	131 mm	100 mm	77 mm	800 g	560	Y	Oct 2013	US$ 1 299	ebay.com
10.		Pentax K-3 II	131 mm	100 mm	77 mm	800 g	720	Y	Apr 2015	US$ 1 099	ebay.com
11.		Pentax K-50	130 mm	97 mm	71 mm	650 g	410	Y	Jun 2013	US$ 599	ebay.com
12.		Pentax K-500	130 mm	97 mm	71 mm	646 g	710	n	Jun 2013	US$ 549	ebay.com
13.		Pentax K-S2	123 mm	91 mm	73 mm	678 g	410	Y	Feb 2015	US$ 749	ebay.com
14.		Sony A58	129 mm	95 mm	78 mm	492 g	690	n	Feb 2013	US$ 599	ebay.com
15.		Sony A68	143 mm	104 mm	81 mm	610 g	540	n	Nov 2015	US$ 699	ebay.com
16.		Sony RX10 II	129 mm	88 mm	102 mm	813 g	400	Y	Jun 2015	US$ 1 299	ebay.com
17.		Sony RX10 III	133 mm	94 mm	127 mm	1051 g	420	Y	Mar 2016	US$ 1 499	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 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. 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 sensor inside a digital camera is one of the key determinants 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. 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 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 RX10 an one-inch sensor. The sensor area in the RX10 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.

Even though the K-S1 has a larger sensor, both cameras offer the same resolution of 20 megapixels. This implies that the K-S1 has a lower pixel density and larger individual pixels (with a pixel pitch of 4.28μm versus 2.41μm for the RX10), which gives it a potential advantage in terms of light gathering capacity. In addition, the K-S1 is a somewhat more recent model (by 10 months) than the RX10, and its sensor might have benefitted from technological advances during this time. 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 Pentax K-S1 has a native sensitivity range from ISO 100 to ISO 51200. The corresponding ISO settings for the Sony Cyber-shot DSC-RX10 are ISO 125 to ISO 12800, with the possibility to increase the ISO range to 80-25600.

In terms of underlying technology, the K-S1 is build around a CMOS sensor, while the RX10 uses a BSI-CMOS imager. 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 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. Of the two cameras under review, the K-S1 has a notably higher overall DXO score than the RX10 (overall score 9 points higher), which gives it an advantage in terms of imaging quality. This advantage is based on 0.6 bits higher color depth, 0.4 EV in additional dynamic range, and 1.2 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-S1	APS-C	20.0	5472	3648	1080/30p	23.5	13.0	1061	78
2.		Sony RX10	1-inch	20.0	5472	3648	1080/60p	22.9	12.6	474	69
3.		Canon 70D	APS-C	20.0	5472	3648	1080/30p	22.5	11.6	926	68
4.		Canon 80D	APS-C	24.0	6000	4000	1080/60p	23.6	13.2	1135	79
5.		Canon 750D	APS-C	24.0	6000	4000	1080/30p	22.7	12.0	919	71
6.		Canon 760D	APS-C	24.0	6000	4000	1080/30p	22.6	12.0	915	70
7.		Nikon D5300	APS-C	24.0	6000	4000	1080/60p	24.0	13.9	1338	83
8.		Nikon D7100	APS-C	24.0	6000	4000	1080/60p	24.2	13.7	1256	83
9.		Pentax K-3	APS-C	24.1	6016	4000	1080/60i	23.7	13.4	1216	80
10.		Pentax K-3 II	APS-C	24.1	6016	4000	1080/60i	23.6	13.6	1106	80
11.		Pentax K-50	APS-C	16.1	4928	3264	1080/30p	23.7	13.0	1120	79
12.		Pentax K-500	APS-C	16.1	4928	3264	1080/30p	23.7	13.1	1087	79
13.		Pentax K-S2	APS-C	20.0	5472	3648	1080/30p	23.6	12.9	1514	79
14.		Sony A58	APS-C	19.8	5456	3632	1080/60i	23.3	12.5	753	74
15.		Sony A68	APS-C	24.0	6000	4000	1080/60i	24.1	13.5	701	79
16.		Sony RX10 II	1-inch	20.0	5472	3648	4K/30p	23.0	12.6	531	70
17.		Sony RX10 III	1-inch	20.0	5472	3648	4K/30p	23.1	12.6	472	70
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. Both cameras under consideration have a sensor with sufficiently fast read-out times for moving pictures, but the RX10 provides a faster frame rate than the K-S1. It can shoot movie footage at 1080/60p, while the Pentax is limited to 1080/30p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a range of features. For example, the RX10 has an electronic viewfinder (1440k dots), while the K-S1 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 viewfinders of both cameras offer the same field of view (100%), but the viewfinder of the RX10 has a higher magnification than the one of the K-S1 (0.70x vs 0.63x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The following table reports on some other key feature differences and similarities of the Pentax K-S1, the Sony RX10, 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.		Pentax K-S1	optical	n	3.0 / 921	fixed	n	1/6000s	5.4/s	Y	Y
2.		Sony RX10	1440	Y	3.0 / 1229	tilting	n	1/3200s	10.0/s	Y	Y
3.		Canon 70D	optical	Y	3.0 / 1040	swivel	Y	1/8000s	7.0/s	Y	n
4.		Canon 80D	optical	Y	3.0 / 1040	swivel	Y	1/8000s	7.0/s	Y	n
5.		Canon 750D	optical	n	3.0 / 1040	swivel	Y	1/4000s	5.0/s	Y	n
6.		Canon 760D	optical	Y	3.0 / 1040	swivel	Y	1/4000s	5.0/s	Y	n
7.		Nikon D5300	optical	n	3.2 / 1037	swivel	n	1/4000s	5.0/s	Y	n
8.		Nikon D7100	optical	Y	3.2 / 1229	fixed	n	1/8000s	6.0/s	Y	n
9.		Pentax K-3	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	Y	Y
10.		Pentax K-3 II	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	n	Y
11.		Pentax K-50	optical	n	3.0 / 921	fixed	n	1/6000s	6.0/s	Y	Y
12.		Pentax K-500	optical	n	3.0 / 921	fixed	n	1/6000s	6.0/s	Y	Y
13.		Pentax K-S2	optical	n	3.0 / 921	swivel	n	1/6000s	5.4/s	Y	Y
14.		Sony A58	1440	n	2.7 / 460	tilting	n	1/4000s	5.0/s	Y	Y
15.		Sony A68	1440	Y	2.7 / 460	tilting	n	1/4000s	8.0/s	Y	Y
16.		Sony RX10 II	2359	Y	3.0 / 1229	tilting	n	1/3200s	14.0/s	Y	Y
17.		Sony RX10 III	2359	Y	3.0 / 1229	tilting	n	1/2000s	14.0/s	Y	Y
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that is present on the RX10, but is missing on the K-S1 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 K-S1 writes its imaging data to SDXC cards, while the RX10 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 Pentax K-S1 and Sony Cyber-shot DSC-RX10 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 RX10	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
3.		Canon 70D	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
4.		Canon 80D	Y	stereo / mono	Y	Y	mini	2.0	Y	Y	-
5.		Canon 750D	Y	stereo / mono	Y	-	mini	2.0	Y	Y	-
6.		Canon 760D	Y	stereo / mono	Y	-	mini	2.0	Y	Y	-
7.		Nikon D5300	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
8.		Nikon D7100	Y	stereo / mono	Y	Y	mini	2.0	-	-	-
9.		Pentax K-3	Y	mono / mono	Y	Y	mini	3.0	-	-	-
10.		Pentax K-3 II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
11.		Pentax K-50	Y	mono / mono	-	-	micro	2.0	-	-	-
12.		Pentax K-500	Y	mono / mono	-	-	-	2.0	-	-	-
13.		Pentax K-S2	Y	mono / mono	Y	-	micro	2.0	Y	Y	-
14.		Sony A58	Y	stereo / mono	Y	-	mini	2.0	-	-	-
15.		Sony A68	Y	stereo / mono	Y	-	micro	2.0	-	-	-
16.		Sony RX10 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
17.		Sony RX10 III	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-

It is notable that the RX10 offers wifi support, which can be a very convenient means to transfer image data to an off-camera location. In contrast, the K-S1 does not provide wifi capability.

Both the K-S1 and the RX10 have been discontinued, but can regularly be found used on ebay. The RX10 was replaced by the Sony RX10 II, while the K-S1 was followed by the Pentax K-S2. Further information on the features and operation of the K-S1 and RX10 can be found, respectively, in the Pentax K-S1 Manual (free pdf) or the online Sony RX10 Manual.

Review summary

So what conclusions can be drawn? Which of the two cameras – the Pentax K-S1 or the Sony RX10 – has the upper hand? Is one clearly better than the other? Below is a summary of the relative strengths of each of the two contestants.

Reasons to prefer the Pentax K-S1:

• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• Better image quality: Scores markedly higher (9 points) in the DXO overall assessment.
• Better low-light sensitivity: Requires less light for good images (1.2 stops ISO advantage).
• Brighter framing: Features an optical viewfinder for clear, lag-free composition.
• Faster shutter: Has higher mechanical shutter speed (1/6000s vs 1/3200s) to freeze action.
• More flexible: Can take a variety of interchangeable lenses, including specialty optics.
• More modern: Is somewhat more recent (announced 10 months after the RX10).

Arguments in favor of the Sony Cyber-shot DSC-RX10:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Better video: Provides higher movie framerates (1080/60p versus 1080/30p).
• Better sound: Can connect to an external microphone for higher quality sound recording.
• Better sound control: Has a headphone port that enables audio monitoring while recording.
• More framing info: Has an electronic viewfinder that displays shooting data.
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.70x vs 0.63x).
• Easier setting verification: Features a control panel on top to check shooting parameters.
• More detailed LCD: Has a higher resolution rear screen (1229k vs 921k dots).
• More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
• Faster burst: Shoots at higher frequency (10 vs 5.4 flaps/sec) to capture the decisive moment.
• Ready to shoot: Comes with an integrated lens, while the K-S1 requires a separate lens.
• Easier travel charging: Can be conveniently charged via its USB port.
• Better sealing: Is splash and dust sealed for shooting in inclement weather conditions.
• 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 heavily discounted: Has been on the market for longer (launched in October 2013).

If the number of relative strengths (bullet points above) is taken as a guide, the RX10 is the clear winner of the contest (16 : 7 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 RX10 place the cameras among the top in their class? Find out in the latest Best DSLR Camera and Best Travel-Zoom 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 partial and cannot reveal, for example, the shooting experience and imaging performance when actually working with the K-S1 or the RX10. 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	Street Price
1.		Pentax K-S1	4/5	..	..	..	4.5/5	4/5	Aug 2014	US$ 749	ebay.com
2.		Sony RX10	5/5	+	..	80/100	4.5/5	4.5/5	Oct 2013	US$ 1 299	ebay.com
3.		Canon 70D	5/5	+ +	..	83/100	4.5/5	5/5	Jul 2013	US$ 1 199	ebay.com
4.		Canon 80D	4/5	+ +	4.5/5	84/100	4.5/5	4.5/5	Feb 2016	US$ 1 199	ebay.com
5.		Canon 750D	5/5	..	..	75/100	4.5/5	4.5/5	Feb 2015	US$ 749	ebay.com
6.		Canon 760D	5/5	+	..	77/100	4.5/5	4.5/5	Feb 2015	US$ 649	ebay.com
7.		Nikon D5300	4/5	+ +	..	79/100	4.5/5	4.5/5	Oct 2013	US$ 799	ebay.com
8.		Nikon D7100	5/5	+ +	..	85/100	4.5/5	4.5/5	Feb 2013	US$ 1 199	ebay.com
9.		Pentax K-3	4/5	..	..	83/100	5/5	5/5	Oct 2013	US$ 1 299	ebay.com
10.		Pentax K-3 II	4.5/5	..	..	..	5/5	5/5	Apr 2015	US$ 1 099	ebay.com
11.		Pentax K-50	5/5	..	..	..	5/5	4.5/5	Jun 2013	US$ 599	ebay.com
12.		Pentax K-500	..	..	..	..	4.5/5	4.5/5	Jun 2013	US$ 549	ebay.com
13.		Pentax K-S2	4.5/5	..	..	..	5/5	4.5/5	Feb 2015	US$ 749	ebay.com
14.		Sony A58	3/5	..	..	..	4.5/5	4.5/5	Feb 2013	US$ 599	ebay.com
15.		Sony A68	3/5	..	..	..	4/5	4/5	Nov 2015	US$ 699	ebay.com
16.		Sony RX10 II	5/5	+ +	..	82/100	4.5/5	4/5	Jun 2015	US$ 1 299	ebay.com
17.		Sony RX10 III	5/5	+	..	84/100	4.5/5	4.5/5	Mar 2016	US$ 1 499	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

Care should be taken when interpreting the review scores above, though. The assessments were made in relation to similar cameras of the same technological generation. Hence, a score should always be seen in the context of the camera's market launch date and its price, 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 K-S1 offers at
ebay.com
Check RX10 offers at
ebay.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. Alternatively, you can follow any of the listed hyperlinks for comparisons that others found interesting.

~

Check K-S1 offers at
ebay.com
Check RX10 offers at
ebay.com

Did you notice an error on this page? If so, please get in touch, so that we can correct the information.