Pentax K-S1 vs Sigma fp L

The Pentax K-S1 and the Sigma fp L are two digital cameras that were revealed to the public, respectively, in August 2014 and March 2021. The K-S1 is a DSLR, while the fp L is a mirrorless interchangeable lens camera. The cameras are based on an APS-C (K-S1) and a full frame (fp L) sensor. The Pentax has a resolution of 20 megapixels, whereas the Sigma provides 60.2 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		Sigma fp L
Digital single lens reflex		Mirrorless system camera
Pentax K mount lenses		Leica L mount lenses
20 MP – APS-C sensor		60.2 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
Fixed screen (not touch-sensitive)		Fixed touchscreen
5.4 shutter flaps per second		10 shutter flaps per second
In-body stabilization		Lens stabilization only
not weather sealed		Weathersealed body
410 shots per battery charge		240 shots per battery charge
121 x 93 x 70 mm, 558 g		113 x 70 x 45 mm, 427 g

Check K-S1 offers at
ebay.com
Check fp L price at
amazon.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Pentax K-S1 and the Sigma fp L? 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 K-S1 and the Sigma fp L 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 measures are rounded to the nearest millimeter.

The K-S1 can be obtained in four different colors (black, grey, orange, white), while the fp L 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 L is notably smaller (30 percent) than the Pentax K-S1. Moreover, the fp L is markedly lighter (23 percent) than the K-S1. It is noteworthy in this context that the fp L 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 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-S1 gets 410 shots out of its Pentax D-LI109 battery, while the fp L can take 240 images on a single charge of its Sigma BP-51 power pack. The power pack in the fp L 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 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.		Sigma fp L	113 mm	70 mm	45 mm	427 g	240	Y	Mar 2021	2,499	amazon.com
3.		Leica M11	139 mm	80 mm	39 mm	640 g	700	Y	Jan 2022	8,995	amazon.com
4.		Nikon D780	144 mm	116 mm	76 mm	840 g	2260	Y	Jan 2020	2,299	amazon.com
5.		Nikon D5300	125 mm	98 mm	76 mm	480 g	600	n	Oct 2013	799	ebay.com
6.		Nikon D5500	124 mm	97 mm	70 mm	470 g	820	n	Jan 2015	899	ebay.com
7.		Pentax K-3	131 mm	100 mm	77 mm	800 g	560	Y	Oct 2013	1,299	ebay.com
8.		Pentax K-3 II	131 mm	100 mm	77 mm	800 g	720	Y	Apr 2015	1,099	ebay.com
9.		Pentax K-30	130 mm	97 mm	71 mm	650 g	410	Y	May 2012	849	ebay.com
10.		Pentax K-50	130 mm	97 mm	71 mm	650 g	410	Y	Jun 2013	599	ebay.com
11.		Pentax K-500	130 mm	97 mm	71 mm	646 g	710	n	Jun 2013	549	ebay.com
12.		Pentax K-S2	123 mm	91 mm	73 mm	678 g	410	Y	Feb 2015	749	ebay.com
13.		Sigma fp	113 mm	70 mm	45 mm	422 g	280	Y	Jul 2019	1,899	amazon.com
14.		Sony A7R	127 mm	94 mm	48 mm	465 g	340	Y	Oct 2013	2,299	ebay.com
15.		Sony A7S	127 mm	94 mm	48 mm	489 g	380	Y	Apr 2014	2,499	ebay.com
16.		Sony A58	129 mm	95 mm	78 mm	492 g	690	n	Feb 2013	599	ebay.com
17.		Sony A68	143 mm	104 mm	81 mm	610 g	540	n	Nov 2015	699	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 listed launch prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The K-S1 was launched at a markedly lower price (by 70 percent) than the fp L, 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 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. Furthermore, a large sensor camera will give the photographer more possibilities to use shallow depth-of-field in order to 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 Sigma fp L a full frame sensor. The sensor area in the fp L is 135 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 60.2MP, the fp L offers a higher resolution than the K-S1 (20MP), but the fp L has smaller individual pixels (pixel pitch of 3.79μm versus 4.28μm for the K-S1). Yet, the fp L is a much more recent model (by 6 years and 6 months) than the K-S1, and its sensor will have benefitted from technological advances during this time that enhance the light gathering capacity of its pixel-units. 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 Sigma fp L implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the fp L for good quality output (200 dots per inch) amounts to 47.6 x 31.6 inches or 120.9 x 80.4 cm, for very good quality (250 dpi) 38.1 x 25.3 inches or 96.7 x 64.3 cm, and for excellent quality (300 dpi) 31.7 x 21.1 inches or 80.6 x 53.6 cm. The corresponding values for the Pentax K-S1 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-S1 has a native sensitivity range from ISO 100 to ISO 51200. The corresponding ISO settings for the Sigma fp L are ISO 100 to ISO 25600, with the possibility to increase the ISO range to 6-102400.

In terms of underlying technology, the K-S1 is build around a CMOS sensor, while the fp L 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 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 adjacent table reports on the physical sensor characteristics and the outcomes of the DXO sensor quality tests for a sample of comparator-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.		Sigma fp L	Full Frame	60.2	9520	6328	4K/30p	25.3	14.4	3001	96
3.		Leica M11	Full Frame	60.3	9528	6328	none	26.3	14.8	3376	100
4.		Nikon D780	Full Frame	24.3	6048	4024	4K/30p	25.3	14.3	2877	95
5.		Nikon D5300	APS-C	24.0	6000	4000	1080/60p	24.0	13.9	1338	83
6.		Nikon D5500	APS-C	24.0	6000	4000	1080/60p	24.1	14.0	1438	84
7.		Pentax K-3	APS-C	24.1	6016	4000	1080/60i	23.7	13.4	1216	80
8.		Pentax K-3 II	APS-C	24.1	6016	4000	1080/60i	23.6	13.6	1106	80
9.		Pentax K-30	APS-C	16.1	4928	3264	1080/30p	23.7	13.0	1129	79
10.		Pentax K-50	APS-C	16.1	4928	3264	1080/30p	23.7	13.0	1120	79
11.		Pentax K-500	APS-C	16.1	4928	3264	1080/30p	23.7	13.1	1087	79
12.		Pentax K-S2	APS-C	20.0	5472	3648	1080/30p	23.6	12.9	1514	79
13.		Sigma fp	Full Frame	24.0	6000	4000	4K/30p	25.2	14.2	2829	94
14.		Sony A7R	Full Frame	36.2	7360	4912	1080/60p	25.6	14.1	2746	95
15.		Sony A7S	Full Frame	12.0	4240	2832	1080/60p	23.9	13.2	3702	87
16.		Sony A58	APS-C	19.8	5456	3632	1080/60i	23.3	12.5	753	74
17.		Sony A68	APS-C	24.0	6000	4000	1080/60i	24.1	13.5	701	79
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. Both cameras under consideration have a sensor with sufficiently fast read-out times for moving pictures, but the fp L 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

Apart from 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 fp L relies on live view and the rear LCD for framing. That said, the fp L 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-S1, the Sigma fp L, 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.		Sigma fp L	optional	n	3.2 / 2100	fixed	Y	1/8000s	10.0/s	n	n
3.		Leica M11	optical	n	3.0 / 2333	fixed	Y	1/4000s	4.5/s	n	n
4.		Nikon D780	optical	Y	3.2 / 2359	tilting	Y	1/8000s	12.0/s	n	n
5.		Nikon D5300	optical	n	3.2 / 1037	swivel	n	1/4000s	5.0/s	Y	n
6.		Nikon D5500	optical	n	3.2 / 1037	swivel	Y	1/4000s	5.0/s	Y	n
7.		Pentax K-3	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	Y	Y
8.		Pentax K-3 II	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	n	Y
9.		Pentax K-30	optical	n	3.0 / 921	fixed	n	1/6000s	6.0/s	Y	Y
10.		Pentax K-50	optical	n	3.0 / 921	fixed	n	1/6000s	6.0/s	Y	Y
11.		Pentax K-500	optical	n	3.0 / 921	fixed	n	1/6000s	6.0/s	Y	Y
12.		Pentax K-S2	optical	n	3.0 / 921	swivel	n	1/6000s	5.4/s	Y	Y
13.		Sigma fp	optional	n	3.2 / 2100	fixed	Y	1/8000s	12.0/s	n	n
14.		Sony A7R	2400	n	3.0 / 1230	tilting	n	1/8000s	4.0/s	n	n
15.		Sony A7S	2400	n	3.0 / 921	tilting	n	1/8000s	5.0/s	n	n
16.		Sony A58	1440	n	2.7 / 460	tilting	n	1/4000s	5.0/s	Y	Y
17.		Sony A68	1440	Y	2.7 / 460	tilting	n	1/4000s	8.0/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 fp L 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 fp L 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 Sigma fp L 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 K-S1 and the fp L write their files to SDXC cards. The fp L supports UHS-II cards (Ultra High Speed data transfer of up to 312 MB/s), while the K-S1 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-S1 and Sigma fp L 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.		Sigma fp L	Y	stereo / mono	Y	Y	micro	3.2	Y	-	-
3.		Leica M11	Y	- / -	-	-	-	3.2	Y	-	Y
4.		Nikon D780	Y	stereo / mono	Y	Y	mini	3.1	Y	-	Y
5.		Nikon D5300	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
6.		Nikon D5500	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
7.		Pentax K-3	Y	mono / mono	Y	Y	mini	3.0	-	-	-
8.		Pentax K-3 II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
9.		Pentax K-30	Y	mono / mono	-	-	-	2.0	-	-	-
10.		Pentax K-50	Y	mono / mono	-	-	micro	2.0	-	-	-
11.		Pentax K-500	Y	mono / mono	-	-	-	2.0	-	-	-
12.		Pentax K-S2	Y	mono / mono	Y	-	micro	2.0	Y	Y	-
13.		Sigma fp	Y	stereo / mono	Y	-	micro	3.1	-	-	-
14.		Sony A7R	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
15.		Sony A7S	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
16.		Sony A58	Y	stereo / mono	Y	-	mini	2.0	-	-	-
17.		Sony A68	Y	stereo / mono	Y	-	micro	2.0	-	-	-

It is notable that the fp L 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.

The fp L is a recent model that features in the current product line-up of Sigma. 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 fp L can be found, respectively, in the Pentax K-S1 Manual (free pdf) or the online Sigma fp L Manual.

Review summary

So how do things add up? Which of the two cameras – the Pentax K-S1 or the Sigma fp L – 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.

Arguments in favor of the Pentax K-S1:

• 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.
• 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.
• More affordable: Was introduced into a lower priced category (70 percent cheaper at launch).
• More heavily discounted: Has been available for much longer (launched in August 2014).

Advantages of the Sigma fp L:

• More detail: Has more megapixels (60.2 vs 20MP), which boosts linear resolution by 74%.
• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• 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).
• 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.
• 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 (10 vs 5.4 flaps/sec) to capture the decisive moment.
• Less disturbing: Has an electronic shutter option for completely silent shooting.
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• More compact: Is smaller (113x70mm vs 121x93mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 131g or 23 percent) and is thus easier to take along.
• Easier travel charging: Can be conveniently charged via its USB port.
• Better sealing: Is splash and dust sealed for shooting in inclement weather conditions.
• More legacy lens friendly: Can use many non-native lenses via adapters.
• Faster data transfer: Supports a more advanced USB protocol (3.2 vs 2.0).
• Easier file upload: Has wifi built in for automatic backup or image transfer to the web.
• Faster buffer clearing: Supports a more advanced SD data transfer standard (UHS-II vs UHS-I).
• More modern: Reflects 6 years and 6 months of technical progress since the K-S1 launch.

If the number of relative strengths (bullet points above) is taken as a guide, the fp L is the clear winner of the contest (25 : 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 Sigma fp L 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 technical specifications can provide a useful overview of the capabilities of different cameras, it says little about, for example, the shooting experience and imaging performance of the K-S1 and the fp L in practical situations. 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 where reviews by experts come in. 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.		Sigma fp L	4/5	..	4/5	..	4/5	4/5	Mar 2021	2,499	amazon.com
3.		Leica M11	4.5/5	..	4.5/5	..	4.5/5	4.5/5	Jan 2022	8,995	amazon.com
4.		Nikon D780	5/5	..	5/5	87/100	4.5/5	4.5/5	Jan 2020	2,299	amazon.com
5.		Nikon D5300	4/5	+ +	..	79/100	4.5/5	4.5/5	Oct 2013	799	ebay.com
6.		Nikon D5500	5/5	+	..	79/100	4.5/5	4.5/5	Jan 2015	899	ebay.com
7.		Pentax K-3	4/5	..	..	83/100	5/5	5/5	Oct 2013	1,299	ebay.com
8.		Pentax K-3 II	4.5/5	..	..	..	5/5	5/5	Apr 2015	1,099	ebay.com
9.		Pentax K-30	4/5	..	..	78/100	4.5/5	4.5/5	May 2012	849	ebay.com
10.		Pentax K-50	5/5	..	..	..	5/5	4.5/5	Jun 2013	599	ebay.com
11.		Pentax K-500	..	..	..	..	4.5/5	4.5/5	Jun 2013	549	ebay.com
12.		Pentax K-S2	4.5/5	..	..	..	5/5	4.5/5	Feb 2015	749	ebay.com
13.		Sigma fp	4/5	..	4/5	..	4/5	4.5/5	Jul 2019	1,899	amazon.com
14.		Sony A7R	5/5	+ +	..	82/100	4.5/5	5/5	Oct 2013	2,299	ebay.com
15.		Sony A7S	4/5	..	..	86/100	4.5/5	5/5	Apr 2014	2,499	ebay.com
16.		Sony A58	3/5	..	..	..	4.5/5	4.5/5	Feb 2013	599	ebay.com
17.		Sony A68	3/5	..	..	..	4/5	4/5	Nov 2015	699	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. A score, therefore, has to be seen in close connection to the price and market introduction time 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. Also, please note that some of the review sites have changed their methodology and reporting over time.

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Other camera comparisons

Did this review help to inform your camera decision process? In case you would like to check on the differences and similarities of other camera models, just make your choice using the following search menu. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored.

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