Fujifilm X-A5 vs Pentax K-S1

The Fujifilm X-A5 and the Pentax K-S1 are two digital cameras that were officially introduced, respectively, in January 2018 and August 2014. The X-A5 is a mirrorless interchangeable lens camera, while the K-S1 is a DSLR. Both cameras are equipped with an APS-C sensor. The Fujifilm has a resolution of 24 megapixels, whereas the Pentax provides 20 MP.

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

Headline Specifications

Fujifilm X-A5		Pentax K-S1
Mirrorless system camera		Digital single lens reflex
Fujifilm X mount lenses		Pentax K mount lenses
24 MP – APS-C sensor		20 MP – APS-C sensor
4K/15p Video		1080/30p Video
ISO 200-12,800 (200 - 51,200)		ISO 100-51,200
No viewfinder, LCD framing		Optical viewfinder
3.0" LCD – 1040k dots		3.0" LCD – 921k dots
Tilting touchscreen		Fixed screen (not touch-sensitive)
6 shutter flaps per second		5.4 shutter flaps per second
Lens stabilization only		In-body stabilization
450 shots per battery charge		410 shots per battery charge
117 x 68 x 40 mm, 361 g		121 x 93 x 70 mm, 558 g

Check X-A5 offers at
ebay.com
Check K-S1 offers at
ebay.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Fujifilm X-A5 and the Pentax K-S1? 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 Fujifilm X-A5 and the Pentax K-S1 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 X-A5 can be obtained in three different colors (silver, brown, pink), while the K-S1 is available in four color-versions (black, grey, orange, white).

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Pentax K-S1 is notably larger (41 percent) than the Fujifilm X-A5. Moreover, the K-S1 is substantially heavier (55 percent) than the X-A5. In this context, it is worth noting that neither the X-A5 nor the K-S1 are weather-sealed.

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 X-A5 gets 450 shots out of its Fujifilm NP-W126S battery, while the K-S1 can take 410 images on a single charge of its Pentax D-LI109 power pack. The power pack in the X-A5 can be charged via the USB port, so that it is not always necessary to take the battery charger along 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.		Fujifilm X-A5	117 mm	68 mm	40 mm	361 g	450	n	Jan 2018	399	ebay.com
2.		Pentax K-S1	121 mm	93 mm	70 mm	558 g	410	n	Aug 2014	749	ebay.com
3.		Fujifilm X-T200	121 mm	84 mm	55 mm	370 g	270	n	Jan 2020	699	ebay.com
4.		Fujifilm X-T30	118 mm	83 mm	47 mm	383 g	380	n	Feb 2019	899	ebay.com
5.		Fujifilm X-A7	119 mm	68 mm	41 mm	320 g	440	n	Sep 2019	499	ebay.com
6.		Fujifilm X-T100	121 mm	83 mm	47 mm	448 g	430	n	May 2018	599	ebay.com
7.		Fujifilm X-E3	121 mm	74 mm	43 mm	337 g	350	n	Sep 2017	899	ebay.com
8.		Fujifilm X-T20	118 mm	83 mm	41 mm	383 g	350	n	Jan 2017	899	ebay.com
9.		Fujifilm X-A3	117 mm	67 mm	40 mm	339 g	410	n	Aug 2016	399	ebay.com
10.		Fujifilm X-A10	117 mm	67 mm	40 mm	331 g	410	n	Dec 2016	399	ebay.com
11.		Fujifilm X-A2	117 mm	67 mm	40 mm	350 g	410	n	Jan 2015	399	ebay.com
12.		Nikon D3500	124 mm	97 mm	70 mm	415 g	1550	n	Aug 2018	429	ebay.com
13.		Nikon D5500	124 mm	97 mm	70 mm	470 g	820	n	Jan 2015	899	ebay.com
14.		Nikon D5300	125 mm	98 mm	76 mm	480 g	600	n	Oct 2013	799	ebay.com
15.		Pentax K-S2	123 mm	91 mm	73 mm	678 g	410	Y	Feb 2015	749	ebay.com
16.		Pentax K-500	130 mm	97 mm	71 mm	646 g	710	n	Jun 2013	549	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 naturally be influenced heavily by the price. The listed launch prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The X-A5 was launched at a markedly lower price (by 47 percent) than the K-S1, which puts it into a different market segment. Normally, street prices remain initially close to the MSRP, but after a couple of months, the first discounts appear. 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. 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.

Both cameras under consideration feature an APS-C sensor, but their sensors differ slightly in size. The sensor area in the K-S1 is 1 percent smaller. They nevertheless have the same format factor of 1.5. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

With 24MP, the X-A5 offers a higher resolution than the K-S1 (20MP), but the X-A5 has smaller individual pixels (pixel pitch of 3.92μm versus 4.28μm for the K-S1). However, the X-A5 is a much more recent model (by 3 years and 5 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 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 Fujifilm X-A5 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the X-A5 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-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 X-A5 has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

The Fujifilm X-A5 has a native sensitivity range from ISO 200 to ISO 12800, which can be extended to ISO 200-51200. The corresponding ISO settings for the Pentax K-S1 are ISO 100 to ISO 51200 (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 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. 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.		Fujifilm X-A5	APS-C	24.0	6000	4000	4K/15p	24.0	13.3	1800	82
2.		Pentax K-S1	APS-C	20.0	5472	3648	1080/30p	23.5	13.0	1061	78
3.		Fujifilm X-T200	APS-C	24.0	6000	4000	4K/30p	24.1	13.6	1991	84
4.		Fujifilm X-T30	APS-C	26.0	6240	4160	4K/30p	24.1	13.5	1895	83
5.		Fujifilm X-A7	APS-C	24.0	6000	4000	4K/30p	24.1	13.6	1955	84
6.		Fujifilm X-T100	APS-C	24.0	6000	4000	4K/15p	24.0	13.4	1829	83
7.		Fujifilm X-E3	APS-C	24.0	6000	4000	4K/30p	23.9	13.3	1764	82
8.		Fujifilm X-T20	APS-C	24.0	6000	4000	4K/30p	23.9	13.2	1704	81
9.		Fujifilm X-A3	APS-C	24.0	6000	4000	1080/60p	23.8	13.1	1664	81
10.		Fujifilm X-A10	APS-C	16.0	4896	3264	1080/30p	23.9	13.2	1691	81
11.		Fujifilm X-A2	APS-C	16.0	4896	3264	1080/30p	23.6	12.8	1515	79
12.		Nikon D3500	APS-C	24.0	6000	4000	1080/60p	24.0	13.4	1851	83
13.		Nikon D5500	APS-C	24.0	6000	4000	1080/60p	24.1	14.0	1438	84
14.		Nikon D5300	APS-C	24.0	6000	4000	1080/60p	24.0	13.9	1338	83
15.		Pentax K-S2	APS-C	20.0	5472	3648	1080/30p	23.6	12.9	1514	79
16.		Pentax K-500	APS-C	16.1	4928	3264	1080/30p	23.7	13.1	1087	79
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 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 X-A5 provides a higher video resolution than the K-S1. It can shoot video footage at 4K/15p, 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 X-A5 relies on live view and the rear LCD for framing. The following table reports on some other key feature differences and similarities of the Fujifilm X-A5, the Pentax K-S1, 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.		Fujifilm X-A5	none	n	3.0 / 1040	tilting	Y	1/4000s	6.0/s	Y	n
2.		Pentax K-S1	optical	n	3.0 / 921	fixed	n	1/6000s	5.4/s	Y	Y
3.		Fujifilm X-T200	2360	n	3.5 / 2780	swivel	Y	1/4000s	8.0/s	Y	n
4.		Fujifilm X-T30	2360	n	3.0 / 1040	tilting	Y	1/4000s	8.0/s	Y	n
5.		Fujifilm X-A7	none	n	3.5 / 2760	swivel	Y	1/4000s	6.0/s	Y	n
6.		Fujifilm X-T100	2360	n	3.0 / 1040	swivel	Y	1/4000s	6.0/s	Y	n
7.		Fujifilm X-E3	2360	n	3.0 / 1040	fixed	Y	1/4000s	8.0/s	n	n
8.		Fujifilm X-T20	2360	n	3.0 / 1040	tilting	Y	1/4000s	8.0/s	Y	n
9.		Fujifilm X-A3	none	n	3.0 / 1040	tilting	Y	1/4000s	6.0/s	Y	n
10.		Fujifilm X-A10	none	n	3.0 / 1040	tilting	n	1/4000s	6.0/s	Y	n
11.		Fujifilm X-A2	none	n	3.0 / 920	tilting	n	1/4000s	5.6/s	Y	n
12.		Nikon D3500	optical	n	3.0 / 921	fixed	n	1/4000s	5.0/s	Y	n
13.		Nikon D5500	optical	n	3.2 / 1037	swivel	Y	1/4000s	5.0/s	Y	n
14.		Nikon D5300	optical	n	3.2 / 1037	swivel	n	1/4000s	5.0/s	Y	n
15.		Pentax K-S2	optical	n	3.0 / 921	swivel	n	1/6000s	5.4/s	Y	Y
16.		Pentax K-500	optical	n	3.0 / 921	fixed	n	1/6000s	6.0/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 differentiating feature between the two cameras concerns the touch sensitivity of the rear screen. The X-A5 has a touchscreen, while the K-S1 has a conventional panel. Touch control can be particularly helpful, for example, for setting the focus point.

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 X-A5 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 Fujifilm X-A5 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 X-A5 and the K-S1 write their files to SDXC 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 Fujifilm X-A5 and Pentax K-S1 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.		Fujifilm X-A5	Y	stereo / mono	Y	-	micro	2.0	Y	-	Y
2.		Pentax K-S1	Y	stereo / mono	-	-	micro	2.0	-	-	-
3.		Fujifilm X-T200	Y	stereo / mono	Y	Y	micro	3.1	Y	-	Y
4.		Fujifilm X-T30	Y	stereo / mono	Y	-	micro	3.1	Y	-	Y
5.		Fujifilm X-A7	Y	stereo / mono	Y	-	micro	2.0	Y	-	Y
6.		Fujifilm X-T100	Y	stereo / mono	Y	-	micro	2.0	Y	-	Y
7.		Fujifilm X-E3	Y	stereo / mono	Y	-	micro	2.0	Y	-	Y
8.		Fujifilm X-T20	Y	stereo / mono	Y	-	micro	2.0	Y	-	-
9.		Fujifilm X-A3	Y	stereo / mono	-	-	micro	2.0	Y	-	-
10.		Fujifilm X-A10	-	stereo / mono	-	-	micro	2.0	Y	-	-
11.		Fujifilm X-A2	Y	stereo / mono	-	-	mini	2.0	Y	-	-
12.		Nikon D3500	Y	mono / mono	-	-	mini	2.0	-	-	Y
13.		Nikon D5500	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
14.		Nikon D5300	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
15.		Pentax K-S2	Y	mono / mono	Y	-	micro	2.0	Y	Y	-
16.		Pentax K-500	Y	mono / mono	-	-	-	2.0	-	-	-
17.		Sony A68	Y	stereo / mono	Y	-	micro	2.0	-	-	-

It is notable that the X-A5 has a microphone port, which is missing on the K-S1. Such an external microphone input can help to substantially improve the quality of audio recordings when a good external microphone is used.

Both the X-A5 and the K-S1 have been discontinued, but can regularly be found used on ebay. The K-S1 was replaced by the Pentax K-S2, while the X-A5 does not have a direct successor. Further information on the features and operation of the X-A5 and K-S1 can be found, respectively, in the Fujifilm X-A5 Manual (free pdf) or the online Pentax K-S1 Manual.

Review summary

So what is the bottom line? Is there a clear favorite between the Fujifilm X-A5 and the Pentax K-S1? Which camera is better? Below is a summary of the relative strengths of each of the two contestants.

Reasons to prefer the Fujifilm X-A5:

• More detail: Offers more megapixels (24 vs 20MP) with a 10% higher linear resolution.
• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Better video: Provides higher definition movie capture (4K/15p vs 1080/30p).
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• Better sound: Can connect to an external microphone for higher quality sound recording.
• More detailed LCD: Has a higher resolution rear screen (1040k vs 921k dots).
• More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
• Fewer buttons to press: Is equipped with a touch-sensitive rear screen to facilitate handling.
• 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.
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• More compact: Is smaller (117x68mm vs 121x93mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 197g or 35 percent) and hence easier to carry around.
• Easier travel charging: Can be conveniently charged via its USB port.
• More legacy lens friendly: Can take a broad range of non-native lenses via adapters.
• 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 into a lower priced category (47 percent cheaper at launch).
• More modern: Reflects 3 years and 5 months of technical progress since the K-S1 launch.

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.
• Faster shutter: Has higher mechanical shutter speed (1/6000s vs 1/4000s) to freeze action.
• Sharper images: Has stabilization technology built-in to reduce the impact of hand-shake.
• More heavily discounted: Has been around for much longer (launched in August 2014).

If the count of relative strengths (bullet points above) is taken as a measure, the X-A5 is the clear winner of the match-up (19 : 5 points). However, the relevance of individual strengths will vary across photographers, so that you might want to apply your own weighing scheme to the summary points when reflecting and deciding on a new camera. 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 Fujifilm X-A5 and the Pentax K-S1 place the cameras among the top in their class? Find out in the latest Best Mirrorless Interchangeable Lens Camera and Best DSLR 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 X-A5 and the K-S1 in practical situations. 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 where reviews by experts come in. The adjacent summary-table relays the overall verdicts of several of the most popular 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.		Fujifilm X-A5	..	+	4.1/5	..	4/5	3.5/5	Jan 2018	399	ebay.com
2.		Pentax K-S1	4/5	..	..	..	4.5/5	4/5	Aug 2014	749	ebay.com
3.		Fujifilm X-T200	3.5/5	..	4/5	82/100	4/5	4.5/5	Jan 2020	699	ebay.com
4.		Fujifilm X-T30	5/5	+ +	5/5	84/100	4.5/5	4.5/5	Feb 2019	899	ebay.com
5.		Fujifilm X-A7	3/5	..	3.5/5	81/100	4/5	3.5/5	Sep 2019	499	ebay.com
6.		Fujifilm X-T100	4/5	+	4.5/5	79/100	4/5	4.5/5	May 2018	599	ebay.com
7.		Fujifilm X-E3	4.5/5	+	4.5/5	84/100	4.5/5	4.5/5	Sep 2017	899	ebay.com
8.		Fujifilm X-T20	5/5	+ +	5/5	82/100	5/5	4.5/5	Jan 2017	899	ebay.com
9.		Fujifilm X-A3	..	..	..	74/100	4.5/5	4/5	Aug 2016	399	ebay.com
10.		Fujifilm X-A10	..	..	..	..	4/5	4/5	Dec 2016	399	ebay.com
11.		Fujifilm X-A2	4/5	..	..	..	4.5/5	4.5/5	Jan 2015	399	ebay.com
12.		Nikon D3500	4/5	..	4/5	75/100	4/5	4.5/5	Aug 2018	429	ebay.com
13.		Nikon D5500	5/5	+	..	79/100	4.5/5	4.5/5	Jan 2015	899	ebay.com
14.		Nikon D5300	4/5	+ +	..	79/100	4.5/5	4.5/5	Oct 2013	799	ebay.com
15.		Pentax K-S2	4.5/5	..	..	..	5/5	4.5/5	Feb 2015	749	ebay.com
16.		Pentax K-500	..	..	..	..	4.5/5	4.5/5	Jun 2013	549	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 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 comparing ratings of very distinct cameras or ones that are far apart in terms of their release date have little meaning. Also, kindly note that some of the listed sites have over time developped their review approaches and their reporting style.

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Other camera comparisons

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