Pentax K-1 II vs K-3 III

The Pentax K-1 II and the Pentax K-3 III are two enthusiast cameras that were revealed to the public, respectively, in February 2018 and March 2021. Both are DSLR (Digital Single Lens Reflex) cameras that are based on a full frame (K-1 II) and an APS-C (K-3 III) sensor. The K-1 II has a resolution of 36.2 megapixels, whereas the K-3 III 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

Pentax K-1 II		Pentax K-3 III
Digital single lens reflex		Digital single lens reflex
Pentax K mount lenses		Pentax K mount lenses
36.2 MP – Full Frame sensor		25.6 MP – APS-C sensor
1080/60i Video		4K/30p Video
ISO 100-819,200		ISO 100-160,000
Optical viewfinder		Optical viewfinder
3.2" LCD – 1037k dots		3.2" LCD – 1620k dots
Fully flexible screen (no touchscreen)		Fixed touchscreen
4.4 shutter flaps per second		12 shutter flaps per second
In-body stabilization		In-body stabilization
Weathersealed body		Weathersealed body
670 shots per battery charge		800 shots per battery charge
137 x 110 x 86 mm, 1010 g		135 x 104 x 74 mm, 820 g

Check K-1 II 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 Pentax K-1 II 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

The physical size and weight of the Pentax K-1 II and the Pentax K-3 III are illustrated in the side-by-side display below. 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.

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 smaller (7 percent) than the Pentax K-1 II. Moreover, the K-3 III is markedly lighter (19 percent) than the K-1 II. 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.

The following table provides a synthesis of the main physical specifications of the two cameras and other similar ones. 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-1 II	137 mm	110 mm	86 mm	1010 g	670	Y	Feb 2018	1,999	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-H1	140 mm	97 mm	86 mm	673 g	310	Y	Feb 2018	1,899	ebay.com
4.		Olympus E-5	142 mm	117 mm	75 mm	873 g	750	Y	Sep 2010	1,699	ebay.com
5.		Panasonic G9	137 mm	97 mm	92 mm	658 g	400	Y	Nov 2017	1,699	ebay.com
6.		Panasonic GH5	139 mm	98 mm	87 mm	725 g	410	Y	Jan 2017	1,999	ebay.com
7.		Panasonic S1R	149 mm	110 mm	97 mm	1016 g	380	Y	Feb 2019	3,699	amazon.com
8.		Panasonic S5	133 mm	98 mm	82 mm	714 g	440	Y	Sep 2020	1,999	amazon.com
9.		Pentax K-1	137 mm	110 mm	86 mm	1010 g	760	Y	Feb 2016	1,799	ebay.com
10.		Pentax K-3	131 mm	100 mm	77 mm	800 g	560	Y	Oct 2013	1,299	ebay.com
11.		Pentax K-3 II	131 mm	100 mm	77 mm	800 g	720	Y	Apr 2015	1,099	ebay.com
12.		Pentax K-70	126 mm	93 mm	74 mm	688 g	410	Y	Jun 2016	649	ebay.com
13.		Pentax KP	132 mm	101 mm	76 mm	703 g	390	Y	Jan 2017	1,099	ebay.com
14.		Sony A7R III	127 mm	96 mm	74 mm	650 g	650	Y	Oct 2017	3,199	ebay.com
15.		Sony A99 II	143 mm	104 mm	76 mm	849 g	490	Y	Sep 2016	3,199	ebay.com
16.		Sony RX10 IV	133 mm	94 mm	145 mm	1095 g	400	Y	Sep 2017	1,699	amazon.com
Note: Measurements and pricing do not include easily detachable parts, such as add-on or interchangeable lenses or optional viewfinders.
Convert to Imperial

The price is, of course, an important factor in any camera decision. 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. The two cameras under review were launched at the same price and fall into the same 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.

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. 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-1 II features a full frame sensor and the Pentax K-3 III an APS-C sensor. The sensor area in the K-3 III is 58 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.0 and 1.5. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

Technology-wise, the K-3 III uses a more advanced image processing engine (PRIME V) than the K-1 II (PRIME IV), with benefits for noise reduction, color accuracy, and processing speed.

With 36.2MP, the K-1 II offers a higher resolution than the K-3 III (25.6MP), but the K-1 II nevertheless has larger individual pixels (pixel pitch of 4.88μm versus 3.76μm for the K-3 III) due to its larger sensor. However, the K-3 III is a much more recent model (by 3 years and 1 month) than the K-1 II, and its sensor will 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 resolution advantage of the Pentax K-1 II implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the K-1 II for good quality output (200 dots per inch) amounts to 36.8 x 24.6 inches or 93.5 x 62.4 cm, for very good quality (250 dpi) 29.4 x 19.6 inches or 74.8 x 49.9 cm, and for excellent quality (300 dpi) 24.5 x 16.4 inches or 62.3 x 41.6 cm. The corresponding values for the Pentax K-3 III are 31 x 20.6 inches or 78.6 x 52.4 cm for good quality, 24.8 x 16.5 inches or 62.9 x 41.9 cm for very good quality, and 20.6 x 13.8 inches or 52.4 x 35 cm for excellent quality prints.

Both cameras have the capacity to capture high quality composite images by combining multiple shots after shifting the sensor by miniscule distances. This multi-shot, pixel-shift mode is most suitable for photography of stationary objects (landscapes, studio scenes).

The Pentax K-1 II has a native sensitivity range from ISO 100 to ISO 819200. The corresponding ISO settings for the Pentax K-3 III are ISO 100 to ISO 160000 (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.

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. 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-1 II	Full Frame	36.2	7360	4912	1080/60i	25.1	14.0	2698	93
2.		Pentax K-3 III	APS-C	25.6	6192	4128	4K/30p	24.2	13.7	2083	85
3.		Fujifilm X-H1	APS-C	24.0	6000	4000	4K/30p	24.0	13.3	1806	82
4.		Olympus E-5	Four Thirds	12.2	4032	3024	720/30p	21.6	10.5	519	56
5.		Panasonic G9	Four Thirds	20.2	5184	3888	4K/60p	23.1	12.8	1138	74
6.		Panasonic GH5	Four Thirds	20.2	5184	3888	4K/60p	23.9	13.0	807	77
7.		Panasonic S1R	Full Frame	46.7	8368	5584	4K/60p	26.4	14.1	3525	100
8.		Panasonic S5	Full Frame	24.0	6000	4000	4K/60p	25.1	14.5	2697	94
9.		Pentax K-1	Full Frame	36.2	7360	4912	1080/60i	25.4	14.6	3280	96
10.		Pentax K-3	APS-C	24.1	6016	4000	1080/60i	23.7	13.4	1216	80
11.		Pentax K-3 II	APS-C	24.1	6016	4000	1080/60i	23.6	13.6	1106	80
12.		Pentax K-70	APS-C	24.0	6000	4000	1080/60i	23.8	13.1	1639	80
13.		Pentax KP	APS-C	24.1	6016	4000	1080/60i	23.9	13.2	1699	81
14.		Sony A7R III	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
15.		Sony A99 II	Full Frame	42.2	7952	5304	4K/30p	25.4	13.4	2317	92
16.		Sony RX10 IV	1-inch	20.0	5472	3648	4K/30p	22.0	12.2	408	63
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. The two cameras under consideration both have sensors whose read-out speed is fast enough to capture moving pictures, but the K-3 III provides a better video resolution than the K-1 II. It can shoot movie footage at 4K/30p, while the K-1 II is limited to 1080/60i.

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. The K-1 II and the K-3 III are similar in the sense that both have an optical viewfinder. The latter is useful for getting a clear image for framing even in brightly lit environments. The viewfinders of both cameras offer the same field of view (100%), as well as the same magnification (0.70x). The following table reports on some other key feature differences and similarities of the Pentax K-1 II, the Pentax K-3 III, 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-1 II	optical	Y	3.2 / 1037	full-flex	n	1/8000s	4.4/s	n	Y
2.		Pentax K-3 III	optical	Y	3.2 / 1620	fixed	Y	1/8000s	12.0/s	n	Y
3.		Fujifilm X-H1	3690	Y	3.0 / 1040	full-flex	Y	1/8000s	14.0/s	n	Y
4.		Olympus E-5	optical	Y	3.0 / 920	swivel	n	1/8000s	5.0/s	Y	Y
5.		Panasonic G9	3680	Y	3.0 / 1040	swivel	Y	1/8000s	20.0/s	n	Y
6.		Panasonic GH5	3680	n	3.2 / 1620	swivel	Y	1/8000s	12.0/s	n	Y
7.		Panasonic S1R	5760	Y	3.2 / 2100	full-flex	Y	1/8000s	9.0/s	n	Y
8.		Panasonic S5	2360	n	3.0 / 1840	swivel	Y	1/8000s	7.0/s	n	Y
9.		Pentax K-1	optical	Y	3.2 / 1037	full-flex	n	1/8000s	4.4/s	n	Y
10.		Pentax K-3	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	Y	Y
11.		Pentax K-3 II	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	n	Y
12.		Pentax K-70	optical	n	3.0 / 921	swivel	n	1/6000s	6.0/s	Y	Y
13.		Pentax KP	optical	n	3.0 / 921	tilting	n	1/6000s	7.0/s	Y	Y
14.		Sony A7R III	3686	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
15.		Sony A99 II	2400	Y	3.0 / 1229	full-flex	n	1/8000s	12.0/s	n	Y
16.		Sony RX10 IV	2359	Y	3.0 / 1440	tilting	Y	1/2000s	24.0/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 K-3 III has a touchscreen, while the K-1 II has a conventional panel. Touch control can be particularly helpful, for example, for setting the focus point.

The Pentax K-1 II 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 K-1 II 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. The K-3 III supports UHS-II cards (on its first slot), while the K-1 II can use UHS-I cards.

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-1 II 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.		Pentax K-1 II	Y	stereo / mono	Y	Y	micro	2.0	Y	-	-
2.		Pentax K-3 III	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
3.		Fujifilm X-H1	Y	stereo / mono	Y	-	micro	3.0	Y	-	-
4.		Olympus E-5	Y	stereo / -	-	-	mini	2.0	-	-	-
5.		Panasonic G9	Y	stereo / mono	Y	Y	full	3.0	Y	-	Y
6.		Panasonic GH5	Y	stereo / mono	Y	Y	full	3.1	Y	-	Y
7.		Panasonic S1R	Y	stereo / mono	Y	Y	full	3.1	Y	-	Y
8.		Panasonic S5	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
9.		Pentax K-1	Y	stereo / mono	Y	Y	micro	2.0	Y	-	-
10.		Pentax K-3	Y	mono / mono	Y	Y	mini	3.0	-	-	-
11.		Pentax K-3 II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
12.		Pentax K-70	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
13.		Pentax KP	Y	stereo / mono	Y	-	-	2.0	Y	-	-
14.		Sony A7R III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
15.		Sony A99 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	Y
16.		Sony RX10 IV	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-

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 both cameras feature internal geolocalization sensors and can record GPS coordinates in their EXIF data.

Both the K-1 II and the K-3 III are recent models that are part of the current product line-up. The K-1 II replaced the earlier Pentax K-1, while the K-3 III followed on from the Pentax K-3 II. Further information on the features and operation of the K-1 II and K-3 III can be found, respectively, in the Pentax K-1 II Manual (free pdf) or the online Pentax K-3 III Manual.

Review summary

So what conclusions can be drawn? Which of the two cameras – the Pentax K-1 II 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 Pentax K-1 II:

• More detail: Offers more megapixels (36.2 vs 25.6MP) with a 19% higher linear resolution.
• More flexible LCD: Has a full-flex screen for odd-angle shots in portrait or landscape orientation.
• More heavily discounted: Has been available for much longer (launched in February 2018).

Arguments in favor of the Pentax K-3 III:

• Better jpgs: Has a more modern image processing engine (PRIME V vs PRIME IV).
• Better video: Provides higher definition movie capture (4K/30p vs 1080/60i).
• More detailed LCD: Has a higher resolution rear screen (1620k vs 1037k dots).
• Fewer buttons to press: Has a touchscreen to facilitate handling and shooting adjustments.
• Faster burst: Shoots at higher frequency (12 vs 4.4 flaps/sec) to capture the decisive moment.
• Less heavy: Has a lower weight (by 190g or 19 percent) and is thus easier to take along.
• Longer lasting: Gets more shots (800 versus 670) out of a single battery charge.
• Faster data transfer: Supports a more advanced USB protocol (3.2 vs 2.0).
• Easier wireless transfer: Supports Bluetooth for image sharing without cables.
• Faster buffer clearing: Supports a more advanced SD data transfer standard (UHS-II vs UHS-I).
• More modern: Reflects 3 years and 1 month of technical progress since the K-1 II launch.

If the count of individual advantages (bullet points above) is taken as a guide, the K-3 III is the clear winner of the contest (11 : 3 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 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-1 II and the Pentax K-3 III place the cameras among the top in their class? Find out in the latest Best DSLR Camera listing 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-1 II or the K-3 III. 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 expert reviews are important. 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.		Pentax K-1 II	..	..	4.5/5	79/100	4.5/5	4.5/5	Feb 2018	1,999	amazon.com
2.		Pentax K-3 III	4/5	..	3/5	..	4.5/5	..	Mar 2021	1,999	amazon.com
3.		Fujifilm X-H1	..	+	5/5	86/100	4.5/5	4.5/5	Feb 2018	1,899	ebay.com
4.		Olympus E-5	4/5	..	..	75/100	4/5	4.5/5	Sep 2010	1,699	ebay.com
5.		Panasonic G9	..	+ +	5/5	85/100	5/5	5/5	Nov 2017	1,699	ebay.com
6.		Panasonic GH5	4.5/5	+ +	..	85/100	4.5/5	5/5	Jan 2017	1,999	ebay.com
7.		Panasonic S1R	4.5/5	..	4.6/5	89/100	4.5/5	4.5/5	Feb 2019	3,699	amazon.com
8.		Panasonic S5	4.5/5	+ +	4.5/5	88/100	4.5/5	4.5/5	Sep 2020	1,999	amazon.com
9.		Pentax K-1	5/5	..	..	84/100	5/5	5/5	Feb 2016	1,799	ebay.com
10.		Pentax K-3	4/5	..	..	83/100	5/5	5/5	Oct 2013	1,299	ebay.com
11.		Pentax K-3 II	4.5/5	..	..	..	5/5	5/5	Apr 2015	1,099	ebay.com
12.		Pentax K-70	4.5/5	..	4/5	79/100	4.5/5	4.5/5	Jun 2016	649	ebay.com
13.		Pentax KP	4/5	..	3/5	82/100	5/5	4.5/5	Jan 2017	1,099	ebay.com
14.		Sony A7R III	..	+ +	4/5	90/100	4.5/5	5/5	Oct 2017	3,199	ebay.com
15.		Sony A99 II	..	..	4.5/5	85/100	4.5/5	4.5/5	Sep 2016	3,199	ebay.com
16.		Sony RX10 IV	5/5	+	3.5/5	84/100	4.5/5	5/5	Sep 2017	1,699	amazon.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. Thus, a score needs to be put into the context of the launch date and the launch price of the camera, and comparisons of ratings among very different cameras or across long time periods have little meaning. Also, please note that some of the review sites have changed their methodology and reporting over time.

Check K-1 II price at
amazon.com
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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Check K-1 II price at
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Check K-3 III price at
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