Pentax K-S2 vs Sigma fp

The Pentax K-S2 and the Sigma fp are two digital cameras that were revealed to the public, respectively, in February 2015 and July 2019. The K-S2 is a DSLR, while the fp is a mirrorless interchangeable lens camera. The cameras are based on an APS-C (K-S2) and a full frame (fp) sensor. The Pentax has a resolution of 20 megapixels, whereas the Sigma 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-S2		Sigma fp
Digital single lens reflex		Mirrorless system camera
Pentax K mount lenses		Leica L mount lenses
20 MP – APS-C sensor		24 MP – Full Frame sensor
1080/30p Video		4K/30p Video
ISO 100-51,200		ISO 100-25,600 (6 - 102,400)
Optical viewfinder		Viewfinder optional
3.0" LCD – 921k dots		3.2" LCD – 2100k dots
Swivel screen (not touch-sensitive)		Fixed touchscreen
5.4 shutter flaps per second		12 shutter flaps per second
In-body stabilization		Lens stabilization only
Weathersealed body		Weathersealed body
410 shots per battery charge		280 shots per battery charge
123 x 91 x 73 mm, 678 g		113 x 70 x 45 mm, 422 g

Check K-S2 offers at
ebay.com
Check fp price at
amazon.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Pentax K-S2 and the Sigma fp? 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-S2 and the Sigma fp. 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 width, height and depth dimensions are rounded to the nearest millimeter.

The K-S2 can be obtained in six different colors (black, grey, pink, orange, green, white), while the fp 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 Sigma fp is notably smaller (29 percent) than the Pentax K-S2. Moreover, the fp is substantially lighter (38 percent) than the K-S2. In this context, it is worth noting that both cameras are splash and dust-proof and can, hence, be used in inclement weather conditions or harsh environments.

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 K-S2 gets 410 shots out of its Pentax D-LI109 battery, while the fp can take 280 images on a single charge of its Sigma BP-51 power pack. The power pack in the fp can be charged via the USB port, which can be very convenient when travelling.

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 K-S2	123 mm	91 mm	73 mm	678 g	410	Y	Feb 2015	749	ebay.com
2.		Sigma fp	113 mm	70 mm	45 mm	422 g	280	Y	Jul 2019	1,899	amazon.com
3.		Fujifilm X-Pro3	141 mm	83 mm	46 mm	497 g	440	Y	Oct 2019	1,799	amazon.com
4.		Nikon D780	144 mm	116 mm	76 mm	840 g	2260	Y	Jan 2020	2,299	amazon.com
5.		Panasonic S1	149 mm	110 mm	97 mm	1017 g	400	Y	Feb 2019	2,499	amazon.com
6.		Panasonic S1H	151 mm	114 mm	110 mm	1052 g	400	Y	May 2019	3,999	amazon.com
7.		Panasonic S5	133 mm	98 mm	82 mm	714 g	440	Y	Sep 2020	1,999	amazon.com
8.		Pentax K-3	131 mm	100 mm	77 mm	800 g	560	Y	Oct 2013	1,299	ebay.com
9.		Pentax K-3 II	131 mm	100 mm	77 mm	800 g	720	Y	Apr 2015	1,099	ebay.com
10.		Pentax K-5	131 mm	97 mm	73 mm	760 g	740	Y	Sep 2010	1,099	ebay.com
11.		Pentax K-30	130 mm	97 mm	71 mm	650 g	410	Y	May 2012	849	ebay.com
12.		Pentax K-50	130 mm	97 mm	71 mm	650 g	410	Y	Jun 2013	599	ebay.com
13.		Pentax K-70	126 mm	93 mm	74 mm	688 g	410	Y	Jun 2016	649	ebay.com
14.		Pentax KP	132 mm	101 mm	76 mm	703 g	390	Y	Jan 2017	1,099	ebay.com
15.		Pentax K-S1	121 mm	93 mm	70 mm	558 g	410	n	Aug 2014	749	ebay.com
16.		Sony A68	143 mm	104 mm	81 mm	610 g	540	n	Nov 2015	699	ebay.com
17.		Sony A77 II	143 mm	104 mm	81 mm	647 g	480	Y	May 2014	1,199	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 manufacturer’s suggested retail prices give an idea on the placement of the camera in the maker’s lineup and the broader market. The K-S2 was launched at a markedly lower price (by 61 percent) than the fp, which puts it into a different market segment. 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 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 tend to be associated with larger, more expensive camera bodies and lenses.

Of the two cameras under consideration, the Pentax K-S2 features an APS-C sensor and the Sigma fp a full frame sensor. The sensor area in the fp is 134 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.

With 24MP, the fp offers a higher resolution than the K-S2 (20MP), but the fp nevertheless has larger individual pixels (pixel pitch of 5.98μm versus 4.28μm for the K-S2) due to its larger sensor. Moreover, the fp is a much more recent model (by 4 years and 5 months) than the K-S2, and its sensor will have benefitted from technological advances during this time that further enhance the light gathering capacity of its pixel-units. Coming back to sensor resolution, it should be mentioned that neither of the two cameras has an anti-alias filter installed, so they are able to capture all the detail the sensor resolves.

The resolution advantage of the Sigma fp implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the fp 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 Pentax K-S2 are 27.4 x 18.2 inches or 69.5 x 46.3 cm for good quality, 21.9 x 14.6 inches or 55.6 x 37.1 cm for very good quality, and 18.2 x 12.2 inches or 46.3 x 30.9 cm for excellent quality prints.

The Pentax K-S2 has a native sensitivity range from ISO 100 to ISO 51200. The corresponding ISO settings for the Sigma fp are ISO 100 to ISO 25600, with the possibility to increase the ISO range to 6-102400.

In terms of underlying technology, the K-S2 is build around a CMOS sensor, while the fp 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.

For many cameras, data on sensor performance has been reported by DXO Mark. 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"). 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-S2	APS-C	20.0	5472	3648	1080/30p	23.6	12.9	1514	79
2.		Sigma fp	Full Frame	24.0	6000	4000	4K/30p	25.2	14.2	2829	94
3.		Fujifilm X-Pro3	APS-C	26.0	6240	4160	4K/30p	24.1	13.6	1968	84
4.		Nikon D780	Full Frame	24.3	6048	4024	4K/30p	25.3	14.3	2877	95
5.		Panasonic S1	Full Frame	24.0	6000	4000	4K/60p	25.2	14.5	3333	95
6.		Panasonic S1H	Full Frame	24.0	6000	4000	6K/30p	25.2	14.2	2805	94
7.		Panasonic S5	Full Frame	24.0	6000	4000	4K/60p	25.1	14.5	2697	94
8.		Pentax K-3	APS-C	24.1	6016	4000	1080/60i	23.7	13.4	1216	80
9.		Pentax K-3 II	APS-C	24.1	6016	4000	1080/60i	23.6	13.6	1106	80
10.		Pentax K-5	APS-C	16.1	4928	3264	1080/25p	23.7	14.1	1162	82
11.		Pentax K-30	APS-C	16.1	4928	3264	1080/30p	23.7	13.0	1129	79
12.		Pentax K-50	APS-C	16.1	4928	3264	1080/30p	23.7	13.0	1120	79
13.		Pentax K-70	APS-C	24.0	6000	4000	1080/60i	23.8	13.1	1639	80
14.		Pentax KP	APS-C	24.1	6016	4000	1080/60i	23.9	13.2	1699	81
15.		Pentax K-S1	APS-C	20.0	5472	3648	1080/30p	23.5	13.0	1061	78
16.		Sony A68	APS-C	24.0	6000	4000	1080/60i	24.1	13.5	701	79
17.		Sony A77 II	APS-C	24.0	6000	4000	1080/60p	24.4	13.4	1013	82
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 also of capturing video footage. Both cameras under consideration are equipped with sensors that have a sufficiently high read-out speed for moving images, but the fp provides a better video resolution than the K-S2. It can shoot movie footage at 4K/30p, while the Pentax is limited to 1080/30p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. For example, the K-S2 has an optical viewfinder, which can be very useful when shooting in bright sunlight. In contrast, the fp relies on live view and the rear LCD for framing. That said, the fp can be equipped with an optional viewfinder – the EVF-11. The following table reports on some other key feature differences and similarities of the Pentax K-S2, the Sigma fp, 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-S2	optical	n	3.0 / 921	swivel	n	1/6000s	5.4/s	Y	Y
2.		Sigma fp	optional	n	3.2 / 2100	fixed	Y	1/8000s	12.0/s	n	n
3.		Fujifilm X-Pro3	3690	n	3.0 / 1620	tilting	Y	1/8000s	8.0/s	n	n
4.		Nikon D780	optical	Y	3.2 / 2359	tilting	Y	1/8000s	12.0/s	n	n
5.		Panasonic S1	5760	Y	3.2 / 2100	full-flex	Y	1/8000s	9.0/s	n	Y
6.		Panasonic S1H	5760	Y	3.2 / 2330	swivel	Y	1/8000s	9.0/s	n	Y
7.		Panasonic S5	2360	n	3.0 / 1840	swivel	Y	1/8000s	7.0/s	n	Y
8.		Pentax K-3	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	Y	Y
9.		Pentax K-3 II	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	n	Y
10.		Pentax K-5	optical	Y	3.0 / 921	fixed	n	1/8000s	7.0/s	Y	Y
11.		Pentax K-30	optical	n	3.0 / 921	fixed	n	1/6000s	6.0/s	Y	Y
12.		Pentax K-50	optical	n	3.0 / 921	fixed	n	1/6000s	6.0/s	Y	Y
13.		Pentax K-70	optical	n	3.0 / 921	swivel	n	1/6000s	6.0/s	Y	Y
14.		Pentax KP	optical	n	3.0 / 921	tilting	n	1/6000s	7.0/s	Y	Y
15.		Pentax K-S1	optical	n	3.0 / 921	fixed	n	1/6000s	5.4/s	Y	Y
16.		Sony A68	1440	Y	2.7 / 460	tilting	n	1/4000s	8.0/s	Y	Y
17.		Sony A77 II	2359	Y	3.0 / 1229	full-flex	n	1/8000s	12.0/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-S2 has one, while the fp does not. While the built-in flash of the K-S2 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 fp is one of those camera that have an additional 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 Pentax K-S2 and the Sigma fp both have 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 K-S2 and the fp write their files to SDXC cards. The fp supports UHS-II cards (Ultra High Speed data transfer of up to 312 MB/s), while the K-S2 can use UHS-I cards (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-S2 and Sigma fp 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-S2	Y	mono / mono	Y	-	micro	2.0	Y	Y	-
2.		Sigma fp	Y	stereo / mono	Y	-	micro	3.1	-	-	-
3.		Fujifilm X-Pro3	Y	stereo / mono	Y	-	-	3.1	Y	-	Y
4.		Nikon D780	Y	stereo / mono	Y	Y	mini	3.1	Y	-	Y
5.		Panasonic S1	Y	stereo / mono	Y	Y	full	3.1	Y	-	Y
6.		Panasonic S1H	Y	stereo / mono	Y	Y	full	3.1	Y	-	Y
7.		Panasonic S5	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
8.		Pentax K-3	Y	mono / mono	Y	Y	mini	3.0	-	-	-
9.		Pentax K-3 II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
10.		Pentax K-5	Y	stereo / mono	Y	-	mini	2.0	-	-	-
11.		Pentax K-30	Y	mono / mono	-	-	-	2.0	-	-	-
12.		Pentax K-50	Y	mono / mono	-	-	micro	2.0	-	-	-
13.		Pentax K-70	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
14.		Pentax KP	Y	stereo / mono	Y	-	-	2.0	Y	-	-
15.		Pentax K-S1	Y	stereo / mono	-	-	micro	2.0	-	-	-
16.		Sony A68	Y	stereo / mono	Y	-	micro	2.0	-	-	-
17.		Sony A77 II	Y	stereo / mono	Y	-	mini	2.0	Y	Y	-

It is notable that the K-S2 offers wifi support, while the fp does not. Wifi can be a very convenient means to transfer image data to an off-camera location.

The fp is a recent model that features in the current product line-up of Sigma. In contrast, the K-S2 has been discontinued (but can be found pre-owned on ebay). There has not been a direct replacement model for the K-S2 from Pentax. Further information on the features and operation of the K-S2 and fp can be found, respectively, in the Pentax K-S2 Manual (free pdf) or the online Sigma fp Manual.

Review summary

So what is the bottom line? Is there a clear favorite between the Pentax K-S2 and the Sigma fp? Which camera is better? A synthesis of the relative strong points of each of the models is listed below.

Arguments in favor of the Pentax K-S2:

• Easier framing: Has an optical viewfinder for image composition and settings control.
• More flexible LCD: Has a swivel screen for odd-angle shots in portrait or landscape orientation.
• More selfie-friendly: Has an articulated screen that can be turned to be front-facing.
• Longer lasting: Can take more shots (410 versus 280) 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.
• 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 affordable: Was introduced into a lower priced category (61 percent cheaper at launch).
• More heavily discounted: Has been available for much longer (launched in February 2015).

Reasons to prefer the Sigma fp:

• More detail: Has more megapixels (24 vs 20MP), which boosts linear resolution by 10%.
• Better image quality: Is equipped with a larger and more technologically advanced sensor.
• Richer colors: The sensor size advantage translates into images with better, more accurate colors.
• More dynamic range: Larger sensor captures a wider spectrum of light and dark details.
• Better low-light sensitivity: Larger sensor produces good images even in poorly lit environments.
• Better video: Provides higher definition movie capture (4K/30p vs 1080/30p).
• Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
• More detailed LCD: Has a higher resolution rear screen (2100k vs 921k dots).
• Fewer buttons to press: Has a touchscreen to facilitate handling and shooting adjustments.
• Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/6000s) to freeze action.
• Faster burst: Shoots at higher frequency (12 vs 5.4 flaps/sec) to capture the decisive moment.
• Less disturbing: Has an electronic shutter option for completely silent shooting.
• More compact: Is smaller (113x70mm vs 123x91mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 256g or 38 percent) and is thus easier to take along.
• Easier travel charging: Can be conveniently charged via its USB port.
• More legacy lens friendly: Can use many non-native lenses via adapters.
• Faster data transfer: Supports a more advanced USB protocol (3.1 vs 2.0).
• Faster buffer clearing: Supports a more advanced SD data transfer standard (UHS-II vs UHS-I).
• More modern: Reflects 4 years and 5 months of technical progress since the K-S2 launch.

If the number of relative strengths (bullet points above) is taken as a guide, the fp is the clear winner of the contest (19 : 10 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 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 Pentax K-S2 and the Sigma fp place the cameras among the top in their class? Find out in the latest Best DSLR Camera and Best Mirrorless Interchangeable Lens 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 remains partial and cannot reveal, for example, the shooting experience and imaging performance when actually working with the K-S2 or the fp. 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 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 K-S2	4.5/5	..	..	..	5/5	4.5/5	Feb 2015	749	ebay.com
2.		Sigma fp	4/5	..	4/5	..	4/5	4.5/5	Jul 2019	1,899	amazon.com
3.		Fujifilm X-Pro3	4/5	+	4/5	85/100	4/5	..	Oct 2019	1,799	amazon.com
4.		Nikon D780	5/5	..	5/5	87/100	4.5/5	4.5/5	Jan 2020	2,299	amazon.com
5.		Panasonic S1	4.5/5	+ +	4.5/5	88/100	4.5/5	4/5	Feb 2019	2,499	amazon.com
6.		Panasonic S1H	..	..	4/5	90/100	..	..	May 2019	3,999	amazon.com
7.		Panasonic S5	4.5/5	+ +	4.5/5	88/100	4.5/5	4.5/5	Sep 2020	1,999	amazon.com
8.		Pentax K-3	4/5	..	..	83/100	5/5	5/5	Oct 2013	1,299	ebay.com
9.		Pentax K-3 II	4.5/5	..	..	..	5/5	5/5	Apr 2015	1,099	ebay.com
10.		Pentax K-5	4/5	..	..	83/100	5/5	4.5/5	Sep 2010	1,099	ebay.com
11.		Pentax K-30	4/5	..	..	78/100	4.5/5	4.5/5	May 2012	849	ebay.com
12.		Pentax K-50	5/5	..	..	..	5/5	4.5/5	Jun 2013	599	ebay.com
13.		Pentax K-70	4.5/5	..	4/5	79/100	4.5/5	4.5/5	Jun 2016	649	ebay.com
14.		Pentax KP	4/5	..	3/5	82/100	5/5	4.5/5	Jan 2017	1,099	ebay.com
15.		Pentax K-S1	4/5	..	..	..	4.5/5	4/5	Aug 2014	749	ebay.com
16.		Sony A68	3/5	..	..	..	4/5	4/5	Nov 2015	699	ebay.com
17.		Sony A77 II	4/5	..	..	80/100	4.5/5	5/5	May 2014	1,199	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. Hence, a score should always be seen in the context of the camera's market launch date and its price, 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.

Check K-S2 offers at
ebay.com
Check fp price at
amazon.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 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-S2 offers at
ebay.com
Check fp price at
amazon.com

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