Fujifilm X-Pro3 vs Pentax K-3 III

The Fujifilm X-Pro3 and the Pentax K-3 III are two enthusiast cameras that were officially introduced, respectively, in October 2019 and March 2021. The X-Pro3 is a mirrorless interchangeable lens camera, while the K-3 III is a DSLR. Both cameras are equipped with an APS-C sensor. The Fujifilm has a resolution of 26 megapixels, whereas the Pentax provides 25.6 MP.

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

Headline Specifications

Fujifilm X-Pro3		Pentax K-3 III
Mirrorless system camera		Digital single lens reflex
Fujifilm X mount lenses		Pentax K mount lenses
26 MP – APS-C sensor		25.6 MP – APS-C sensor
4K/30p Video		4K/30p Video
ISO 160-12,800 (80 - 51,200)		ISO 100-160,000
Electronic viewfinder (3690k dots)		Optical viewfinder
3.0" LCD – 1620k dots		3.2" LCD – 1620k dots
Tilting touchscreen		Fixed touchscreen
8 shutter flaps per second		12 shutter flaps per second
Lens stabilization only		In-body stabilization
Weathersealed body		Weathersealed body
440 shots per battery charge		800 shots per battery charge
141 x 83 x 46 mm, 497 g		135 x 104 x 74 mm, 820 g

Check X-Pro3 price at
amazon.com
Check K-3 III price at
amazon.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Fujifilm X-Pro3 and the Pentax K-3 III? 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 Fujifilm X-Pro3 and the Pentax K-3 III is provided in the side-by-side display below. The two cameras are presented according to their relative size. Three successive views from the front, the top, and the rear are shown. All width, height and depth measures are rounded to the nearest millimeter.

Both cameras are available in two different colors (black, silver).

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Pentax K-3 III is notably larger (20 percent) than the Fujifilm X-Pro3. Moreover, the K-3 III is substantially heavier (65 percent) than the X-Pro3. 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 X-Pro3 gets 440 shots out of its Fujifilm NP-W126S battery, while the K-3 III can take 800 images on a single charge of its Pentax D-LI90 power pack. The power pack in the X-Pro3 can be charged via the USB port, so that it is not always necessary to take the battery charger along when travelling.

The table below summarizes the key physical specs of the two cameras alongside a broader set of comparators. In case you want to display and compare another camera duo, you can use the CAM-parator app to select your camera combination among a large number of options.

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-Pro3	141 mm	83 mm	46 mm	497 g	440	Y	Oct 2019	1,799	amazon.com
2.		Pentax K-3 III	135 mm	104 mm	74 mm	820 g	800	Y	Mar 2021	1,999	amazon.com
3.		Fujifilm X-A5	117 mm	68 mm	40 mm	361 g	450	n	Jan 2018	399	ebay.com
4.		Fujifilm X-H1	140 mm	97 mm	86 mm	673 g	310	Y	Feb 2018	1,899	ebay.com
5.		Fujifilm X-Pro2	141 mm	83 mm	46 mm	495 g	350	Y	Jan 2016	1,699	ebay.com
6.		Fujifilm X-T1	129 mm	90 mm	47 mm	440 g	350	Y	Jan 2014	1,299	ebay.com
7.		Fujifilm X-T2	133 mm	92 mm	49 mm	507 g	340	Y	Jul 2016	1,599	ebay.com
8.		Fujifilm X-T3	133 mm	93 mm	59 mm	539 g	390	Y	Sep 2018	1,499	ebay.com
9.		Fujifilm X-T4	135 mm	93 mm	64 mm	607 g	500	Y	Feb 2020	1,699	ebay.com
10.		Fujifilm X-T100	121 mm	83 mm	47 mm	448 g	430	n	May 2018	599	ebay.com
11.		Fujifilm X100V	128 mm	75 mm	53 mm	478 g	420	Y	Feb 2020	1,399	ebay.com
12.		Pentax K-3	131 mm	100 mm	77 mm	800 g	560	Y	Oct 2013	1,299	ebay.com
13.		Pentax K-3 II	131 mm	100 mm	77 mm	800 g	720	Y	Apr 2015	1,099	ebay.com
14.		Pentax K-70	126 mm	93 mm	74 mm	688 g	410	Y	Jun 2016	649	ebay.com
15.		Pentax KP	132 mm	101 mm	76 mm	703 g	390	Y	Jan 2017	1,099	ebay.com
16.		Samsung NX1	139 mm	102 mm	66 mm	550 g	500	Y	Sep 2014	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 obviously take relative prices into account. 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 X-Pro3 was somewhat cheaper (by 10 percent) than the K-3 III at launch, but both cameras fall into the same price category. 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.

Sensor comparison

The size of the imaging sensor is a crucial determinant 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. 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.

Both cameras under consideration feature an APS-C sensor, but their sensors differ slightly in size. The sensor area in the K-3 III is 2 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 26MP, the X-Pro3 offers a slightly higher resolution than the K-3 III (25.6MP), but the X-Pro3 nevertheless has the same individual pixel size (pixel pitch of 3.76μm) as the K-3 III due to its larger sensor. Moreover, the K-3 III is a somewhat more recent model (by 1 year and 5 months) than the X-Pro3, and its sensor might 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 neither of the two cameras has an anti-alias filter installed, so they are able to capture all the detail the sensor resolves.

The X-Pro3 has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

Unlike the X-Pro3, the K-3 III has the capacity to capture high quality composite images (YESMP) by combining multiple shots after shifting its sensor by miniscule distances. This multi-shot, pixel-shift mode is most suitable for photography of stationary objects (landscapes, studio scenes).

The Fujifilm X-Pro3 has a native sensitivity range from ISO 160 to ISO 12800, which can be extended to ISO 80-51200. The corresponding ISO settings for the Pentax K-3 III are ISO 100 to ISO 160000 (no boost).

In terms of underlying technology, the X-Pro3 is build around a BSI-CMOS sensor, while the K-3 III uses a CMOS imager. The X-Pro3 uses Fujifilm's X-Trans layout of photosites, while the K-3 III employs the more common Bayer array.

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.		Fujifilm X-Pro3	APS-C	26.0	6240	4160	4K/30p	24.1	13.6	1968	84
2.		Pentax K-3 III	APS-C	25.6	6192	4128	4K/30p	24.2	13.7	2083	85
3.		Fujifilm X-A5	APS-C	24.0	6000	4000	4K/15p	24.0	13.3	1800	82
4.		Fujifilm X-H1	APS-C	24.0	6000	4000	4K/30p	24.0	13.3	1806	82
5.		Fujifilm X-Pro2	APS-C	24.0	6000	4000	1080/60p	23.7	13.0	1608	80
6.		Fujifilm X-T1	APS-C	16.0	4896	3264	1080/60p	23.5	12.7	1426	77
7.		Fujifilm X-T2	APS-C	24.0	6000	4000	4K/30p	23.8	13.1	1653	81
8.		Fujifilm X-T3	APS-C	26.0	6240	4160	4K/60p	24.0	13.4	1853	83
9.		Fujifilm X-T4	APS-C	26.0	6240	4160	4K/60p	24.1	13.6	1995	84
10.		Fujifilm X-T100	APS-C	24.0	6000	4000	4K/15p	24.0	13.4	1829	83
11.		Fujifilm X100V	APS-C	26.0	6240	4160	4K/30p	24.2	13.6	1996	84
12.		Pentax K-3	APS-C	24.1	6016	4000	1080/60i	23.7	13.4	1216	80
13.		Pentax K-3 II	APS-C	24.1	6016	4000	1080/60i	23.6	13.6	1106	80
14.		Pentax K-70	APS-C	24.0	6000	4000	1080/60i	23.8	13.1	1639	80
15.		Pentax KP	APS-C	24.1	6016	4000	1080/60i	23.9	13.2	1699	81
16.		Samsung NX1	APS-C	28.0	6480	4320	4K/30p	24.2	13.2	1363	83
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 are equipped with sensors that have a sufficiently high read-out speed for moving images, and both provide the same movie specifications (4K/30p).

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. For example, the X-Pro3 has an electronic viewfinder (3690k dots), while the K-3 III 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 viewfinder in the K-3 III offers a wider field of view (100%) than the one in the X-Pro3 (95%), so that a larger proportion of the captured image is visible in the finder. In addition, the viewfinder of the K-3 III has a higher magnification (0.70x vs 0.52x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The table below summarizes some of the other core capabilities of the Fujifilm X-Pro3 and Pentax K-3 III in connection with corresponding information for a sample of similar 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-Pro3	3690	n	3.0 / 1620	tilting	Y	1/8000s	8.0/s	n	n
2.		Pentax K-3 III	optical	Y	3.2 / 1620	fixed	Y	1/8000s	12.0/s	n	Y
3.		Fujifilm X-A5	none	n	3.0 / 1040	tilting	Y	1/4000s	6.0/s	Y	n
4.		Fujifilm X-H1	3690	Y	3.0 / 1040	full-flex	Y	1/8000s	14.0/s	n	Y
5.		Fujifilm X-Pro2	2360	n	3.0 / 1620	fixed	n	1/8000s	8.0/s	n	n
6.		Fujifilm X-T1	2360	n	3.0 / 1040	tilting	n	1/4000s	8.0/s	n	n
7.		Fujifilm X-T2	2360	n	3.0 / 1040	full-flex	n	1/8000s	8.0/s	n	n
8.		Fujifilm X-T3	3690	n	3.0 / 1040	full-flex	Y	1/8000s	11.0/s	n	n
9.		Fujifilm X-T4	3690	n	3.0 / 1620	swivel	Y	1/8000s	15.0/s	n	Y
10.		Fujifilm X-T100	2360	n	3.0 / 1040	swivel	Y	1/4000s	6.0/s	Y	n
11.		Fujifilm X100V	3690	n	3.0 / 1620	tilting	Y	1/4000s	11.0/s	n	n
12.		Pentax K-3	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	Y	Y
13.		Pentax K-3 II	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	n	Y
14.		Pentax K-70	optical	n	3.0 / 921	swivel	n	1/6000s	6.0/s	Y	Y
15.		Pentax KP	optical	n	3.0 / 921	tilting	n	1/6000s	7.0/s	Y	Y
16.		Samsung NX1	2360	Y	3.0 / 1036	tilting	Y	1/8000s	15.0/s	Y	n
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that differentiates the K-3 III and the X-Pro3 is in-body image stabilization (IBIS). The K-3 III reduces the risk of handshake-induced blur with all attached lenses, while the X-Pro3 offers no blur reduction with lenses that themselves do not provide optical image stabilization.

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-Pro3 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-Pro3 and the Pentax K-3 III 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 X-Pro3 and the K-3 III write their files to SDXC cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails. However, while the X-Pro3 supports UHS-II cards (Ultra High Speed data transfer of up to 312 MB/s) on both slots, the K-3 III supports UHS-II only on its first slot and UHS-I (data transfer speed up to 104 MB/s) on the second one.

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-Pro3 and Pentax K-3 III 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-Pro3	Y	stereo / mono	Y	-	-	3.1	Y	-	Y
2.		Pentax K-3 III	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
3.		Fujifilm X-A5	Y	stereo / mono	Y	-	micro	2.0	Y	-	Y
4.		Fujifilm X-H1	Y	stereo / mono	Y	-	micro	3.0	Y	-	-
5.		Fujifilm X-Pro2	Y	stereo / mono	Y	-	micro	2.0	Y	-	-
6.		Fujifilm X-T1	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
7.		Fujifilm X-T2	Y	stereo / mono	Y	-	micro	3.0	Y	-	-
8.		Fujifilm X-T3	Y	stereo / mono	Y	Y	micro	3.1	Y	-	Y
9.		Fujifilm X-T4	Y	stereo / mono	Y	-	micro	3.1	Y	-	Y
10.		Fujifilm X-T100	Y	stereo / mono	Y	-	micro	2.0	Y	-	Y
11.		Fujifilm X100V	Y	stereo / mono	Y	-	micro	3.1	Y	-	Y
12.		Pentax K-3	Y	mono / mono	Y	Y	mini	3.0	-	-	-
13.		Pentax K-3 II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
14.		Pentax K-70	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
15.		Pentax KP	Y	stereo / mono	Y	-	-	2.0	Y	-	-
16.		Samsung NX1	Y	stereo / mono	Y	Y	micro	3.0	Y	Y	Y

It is notable that the K-3 III has a headphone jack, which makes it possible to attach external headphones and monitor the quality of sound during the recording process. The X-Pro3 lacks such a headphone port.

Both cameras feature a PC Sync terminal to control professional strobe lights, which will be appreciated by studio photographers.

Travel and landscape photographers will find it useful that the K-3 III has an internal geolocalization sensor and can record GPS coordinates in its EXIF data.

Both the X-Pro3 and the K-3 III are recent models that are part of the current product line-up. The X-Pro3 replaced the earlier Fujifilm X-Pro2, while the K-3 III followed on from the Pentax K-3 II. Further information on the features and operation of the X-Pro3 and K-3 III can be found, respectively, in the Fujifilm X-Pro3 Manual (free pdf) or the online Pentax K-3 III Manual.

Review summary

So what is the bottom line? Which of the two cameras – the Fujifilm X-Pro3 or the Pentax K-3 III – has the upper hand? Is one clearly better than the other? The listing below highlights the relative strengths of the two models.

Reasons to prefer the Fujifilm X-Pro3:

• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• More framing info: Has an electronic viewfinder that displays shooting data.
• More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
• Less disturbing: Has an electronic shutter option for completely silent shooting.
• More compact: Is smaller (141x83mm vs 135x104mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 323g or 39 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.
• More heavily discounted: Has been on the market for longer (launched in October 2019).

Advantages of the Pentax K-3 III:

• High quality composites: Can combine several shots after pixel-shifting its sensor.
• Better sound control: Has a headphone port that enables audio monitoring while recording.
• Brighter framing: Features an optical viewfinder for clear, lag-free composition.
• More complete view: Has a viewfinder with a larger field of view (100% vs 95%).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.70x vs 0.52x).
• Easier setting verification: Features a control panel on top to check shooting parameters.
• Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
• Faster burst: Shoots at higher frequency (12 vs 8 flaps/sec) to capture the decisive moment.
• Longer lasting: Gets more shots (800 versus 440) out of a single battery charge.
• Sharper images: Has stabilization technology built-in to reduce the impact of hand-shake.
• Easier geotagging: Features an internal GPS sensor to log localization data.
• Faster data transfer: Supports a more advanced USB protocol (3.2 vs 3.1).
• More modern: Was introduced somewhat (1 year and 5 months) more recently.

If the number of relative strengths (bullet points above) is taken as a guide, the K-3 III is the clear winner of the contest (13 : 9 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 Fujifilm X-Pro3 and the Pentax K-3 III 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 specs-based evaluation of cameras can be instructive in revealing their potential as photographic tools, it remains incomplete and does no justice, for example, to the way the X-Pro3 or the K-3 III perform in practice. User reviews, such as those found at amazon, can sometimes inform about these issues, but such feedback is often incomplete, inconsistent, and biased.

Expert reviews

This is why expert reviews 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.		Fujifilm X-Pro3	4/5	+	4/5	85/100	4/5	..	Oct 2019	1,799	amazon.com
2.		Pentax K-3 III	4/5	..	3/5	..	4.5/5	..	Mar 2021	1,999	amazon.com
3.		Fujifilm X-A5	..	+	4.1/5	..	4/5	3.5/5	Jan 2018	399	ebay.com
4.		Fujifilm X-H1	..	+	5/5	86/100	4.5/5	4.5/5	Feb 2018	1,899	ebay.com
5.		Fujifilm X-Pro2	..	+	..	83/100	4.5/5	4.5/5	Jan 2016	1,699	ebay.com
6.		Fujifilm X-T1	5/5	+ +	..	84/100	5/5	5/5	Jan 2014	1,299	ebay.com
7.		Fujifilm X-T2	5/5	+ +	..	86/100	4.5/5	5/5	Jul 2016	1,599	ebay.com
8.		Fujifilm X-T3	5/5	+ +	4.5/5	88/100	5/5	5/5	Sep 2018	1,499	ebay.com
9.		Fujifilm X-T4	5/5	+ +	5/5	88/100	5/5	5/5	Feb 2020	1,699	ebay.com
10.		Fujifilm X-T100	4/5	+	4.5/5	79/100	4/5	4.5/5	May 2018	599	ebay.com
11.		Fujifilm X100V	5/5	+ +	4.5/5	86/100	5/5	4.5/5	Feb 2020	1,399	ebay.com
12.		Pentax K-3	4/5	..	..	83/100	5/5	5/5	Oct 2013	1,299	ebay.com
13.		Pentax K-3 II	4.5/5	..	..	..	5/5	5/5	Apr 2015	1,099	ebay.com
14.		Pentax K-70	4.5/5	..	4/5	79/100	4.5/5	4.5/5	Jun 2016	649	ebay.com
15.		Pentax KP	4/5	..	3/5	82/100	5/5	4.5/5	Jan 2017	1,099	ebay.com
16.		Samsung NX1	5/5	..	..	87/100	5/5	5/5	Sep 2014	1,499	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The review scores listed above should be treated with care, though. The ratings are only valid when referring to cameras in the same category and of the same age. 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 X-Pro3 price at
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Check K-3 III price at
amazon.com

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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