Pentax K-3 III vs Ricoh GR III

The Pentax K-3 III and the Ricoh GR III are two digital cameras that were revealed to the public, respectively, in March 2021 and February 2019. The K-3 III is a DSLR, while the GR III is a fixed lens compact. Both cameras are equipped with an APS-C sensor. The Pentax has a resolution of 25.6 megapixels, whereas the Ricoh 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-3 III		Ricoh GR III
Digital single lens reflex		Fixed lens compact camera
Pentax K mount lenses		28mm f/2.8
25.6 MP – APS-C sensor		24 MP – APS-C sensor
4K/30p Video		1080/60p Video
ISO 100-160,000		ISO 100-102,400
Optical viewfinder		Viewfinder optional
3.2" LCD – 1620k dots		3.0" LCD – 1037k dots
Fixed touchscreen		Fixed touchscreen
12 shutter flaps per second		4 shutter flaps per second
In-body stabilization		In-body stabilization
Weathersealed body		not weather sealed
800 shots per battery charge		200 shots per battery charge
135 x 104 x 74 mm, 820 g		109 x 62 x 33 mm, 257 g

Check K-3 III price at
amazon.com
Check GR III price at
amazon.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Pentax K-3 III and the Ricoh GR 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 Pentax K-3 III and the Ricoh GR III 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 dimensions are rounded to the nearest millimeter.

The K-3 III can be obtained in two different colors (black, silver), while the GR III 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 Ricoh GR III is considerably smaller (52 percent) than the Pentax K-3 III. It is worth mentioning in this context that the K-3 III is splash and dust resistant, while the GR III does not feature any corresponding weather-sealing.

The above size and weight comparisons are to some extent incomplete and possibly misleading, as the GR III has a lens built in, whereas the K-3 III is an interchangeable lens camera that requires a separate lens. Attaching the latter will add extra weight and bulk to the setup.

Concerning battery life, the K-3 III gets 800 shots out of its Pentax D-LI90 battery, while the GR III can take 200 images on a single charge of its Ricoh DB-110 power pack. The power pack in the GR III can be charged via the USB port, which can be very convenient 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.		Pentax K-3 III	135 mm	104 mm	74 mm	820 g	800	Y	Mar 2021	1,999	amazon.com
2.		Ricoh GR III	109 mm	62 mm	33 mm	257 g	200	n	Feb 2019	899	amazon.com
3.		Fujifilm X-H1	140 mm	97 mm	86 mm	673 g	310	Y	Feb 2018	1,899	ebay.com
4.		Fujifilm X-T4	135 mm	93 mm	64 mm	607 g	500	Y	Feb 2020	1,699	ebay.com
5.		Fujifilm XF10	113 mm	64 mm	41 mm	279 g	330	n	Jul 2018	499	ebay.com
6.		Nikon Z6 II	134 mm	101 mm	70 mm	705 g	410	Y	Oct 2020	1,999	amazon.com
7.		Panasonic S5	133 mm	98 mm	82 mm	714 g	440	Y	Sep 2020	1,999	amazon.com
8.		Panasonic ZS200	111 mm	65 mm	45 mm	340 g	370	n	Feb 2018	799	amazon.com
9.		Pentax K-3	131 mm	100 mm	77 mm	800 g	560	Y	Oct 2013	1,299	ebay.com
10.		Pentax K-3 II	131 mm	100 mm	77 mm	800 g	720	Y	Apr 2015	1,099	ebay.com
11.		Pentax K-5 II	131 mm	97 mm	73 mm	760 g	740	Y	Sep 2012	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.		Pentax K-S2	123 mm	91 mm	73 mm	678 g	410	Y	Feb 2015	749	ebay.com
15.		Ricoh GR	117 mm	61 mm	35 mm	245 g	290	n	Apr 2013	799	ebay.com
16.		Ricoh GR II	117 mm	63 mm	35 mm	251 g	320	n	Jun 2015	699	ebay.com
17.		Ricoh GR IIIx	109 mm	62 mm	35 mm	262 g	200	n	Sep 2021	999	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 GR III was launched at a lower price than the K-3 III, despite having a lens built in. 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. 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 are more costly to manufacture and tend to 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 GR III is 2 percent bigger. 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.

Despite having a slightly smaller sensor, the Pentax K-3 III offers a higher resolution of 25.6 megapixels, compared with 24 MP of the Ricoh GR III. This megapixels advantage comes at the cost of a higher pixel density and a smaller size of the individual pixel (with a pixel pitch of 3.76μm versus 3.91μm for the GR III). However, it should be noted that the K-3 III is much more recent (by 2 years and 1 month) than the GR III, and its sensor will have benefitted from technological advances during this time that make it possible to gather light more efficiently. 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 GR III has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

Unlike the GR III, 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 Pentax K-3 III has a native sensitivity range from ISO 100 to ISO 160000. The corresponding ISO settings for the Ricoh GR III are ISO 100 to ISO 102400 (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 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 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-3 III	APS-C	25.6	6192	4128	4K/30p	24.2	13.7	2083	85
2.		Ricoh GR III	APS-C	24.0	6000	4000	1080/60p	24.1	13.5	1897	83
3.		Fujifilm X-H1	APS-C	24.0	6000	4000	4K/30p	24.0	13.3	1806	82
4.		Fujifilm X-T4	APS-C	26.0	6240	4160	4K/60p	24.1	13.6	1995	84
5.		Fujifilm XF10	APS-C	24.0	6000	4000	4K/15p	24.0	13.4	1844	83
6.		Nikon Z6 II	Full Frame	24.3	6048	4024	4K/60p	25.0	14.4	3303	94
7.		Panasonic S5	Full Frame	24.0	6000	4000	4K/60p	25.1	14.5	2697	94
8.		Panasonic ZS200	1-inch	20.0	5472	3648	4K/30p	22.0	12.2	449	64
9.		Pentax K-3	APS-C	24.1	6016	4000	1080/60i	23.7	13.4	1216	80
10.		Pentax K-3 II	APS-C	24.1	6016	4000	1080/60i	23.6	13.6	1106	80
11.		Pentax K-5 II	APS-C	16.1	4928	3264	1080/25p	23.8	14.1	1235	82
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.		Pentax K-S2	APS-C	20.0	5472	3648	1080/30p	23.6	12.9	1514	79
15.		Ricoh GR	APS-C	16.1	4928	3264	1080/30p	23.6	13.5	972	78
16.		Ricoh GR II	APS-C	16.1	4928	3264	1080/30p	23.6	13.7	1078	80
17.		Ricoh GR IIIx	APS-C	24.0	6000	4000	1080/60p	24.2	13.8	2146	85
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. 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 higher video resolution than the GR III. It can shoot video footage at 4K/30p, while the Ricoh is limited to 1080/60p.

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. For example, the K-3 III has an optical viewfinder, which can be very useful when shooting in bright sunlight. In contrast, the GR III relies on live view and the rear LCD for framing. That said, the GR III can be equipped with an optional viewfinder – the GV-1. The following table reports on some other key feature differences and similarities of the Pentax K-3 III, the Ricoh GR 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-3 III	optical	Y	3.2 / 1620	fixed	Y	1/8000s	12.0/s	n	Y
2.		Ricoh GR III	optional	n	3.0 / 1037	fixed	Y	1/4000s	4.0/s	n	Y
3.		Fujifilm X-H1	3690	Y	3.0 / 1040	full-flex	Y	1/8000s	14.0/s	n	Y
4.		Fujifilm X-T4	3690	n	3.0 / 1620	swivel	Y	1/8000s	15.0/s	n	Y
5.		Fujifilm XF10	none	n	3.0 / 1040	fixed	Y	1/4000s	6.0/s	Y	n
6.		Nikon Z6 II	3690	Y	3.2 / 2100	tilting	Y	1/8000s	14.0/s	n	Y
7.		Panasonic S5	2360	n	3.0 / 1840	swivel	Y	1/8000s	7.0/s	n	Y
8.		Panasonic ZS200	2330	n	3.0 / 1240	fixed	Y	1/2000s	10.0/s	Y	Y
9.		Pentax K-3	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	Y	Y
10.		Pentax K-3 II	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	n	Y
11.		Pentax K-5 II	optical	Y	3.0 / 921	fixed	n	1/8000s	7.0/s	Y	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.		Pentax K-S2	optical	n	3.0 / 921	swivel	n	1/6000s	5.4/s	Y	Y
15.		Ricoh GR	optional	n	3.0 / 1230	fixed	n	1/4000s	4.0/s	Y	n
16.		Ricoh GR II	optional	n	3.0 / 1230	fixed	n	1/4000s	4.0/s	Y	n
17.		Ricoh GR IIIx	optional	n	3.0 / 1037	fixed	Y	1/4000s	4.0/s	n	Y
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that is present on the K-3 III, but is missing on the GR III is a top-level LCD. While being, of course, smaller than the rear screen, the control panel conveys some of the essential shooting information and can be convenient for quick and easy settings verification.

The Pentax K-3 III and the Ricoh GR 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-3 III and the GR III write their files to SDXC cards. The K-3 III features dual card slots, which can be very useful in case a memory card fails. In contrast, the GR III only has one slot. The K-3 III supports UHS-II cards (on its first slot), while the GR III 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-3 III and Ricoh GR 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-3 III	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
2.		Ricoh GR III	Y	stereo / mono	-	-	-	3.0	Y	-	Y
3.		Fujifilm X-H1	Y	stereo / mono	Y	-	micro	3.0	Y	-	-
4.		Fujifilm X-T4	Y	stereo / mono	Y	-	micro	3.1	Y	-	Y
5.		Fujifilm XF10	-	stereo / mono	Y	-	micro	2.0	Y	-	Y
6.		Nikon Z6 II	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
7.		Panasonic S5	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
8.		Panasonic ZS200	-	stereo / mono	-	-	micro	2.0	Y	-	Y
9.		Pentax K-3	Y	mono / mono	Y	Y	mini	3.0	-	-	-
10.		Pentax K-3 II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
11.		Pentax K-5 II	Y	stereo / mono	Y	-	mini	2.0	-	-	-
12.		Pentax K-70	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
13.		Pentax KP	Y	stereo / mono	Y	-	-	2.0	Y	-	-
14.		Pentax K-S2	Y	mono / mono	Y	-	micro	2.0	Y	Y	-
15.		Ricoh GR	Y	mono / mono	-	-	micro	2.0	-	-	-
16.		Ricoh GR II	Y	stereo / mono	-	-	micro	2.0	Y	Y	-
17.		Ricoh GR IIIx	Y	stereo / mono	-	-	-	3.0	Y	-	Y

It is notable that the K-3 III has a microphone port, which is missing on the GR III. Such an external microphone input can help to substantially improve the quality of audio recordings when a good external microphone is used.

Studio photographers will appreciate that the Pentax K-3 III (unlike the GR III) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

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

Review summary

So how do things add up? Is the Pentax K-3 III better than the Ricoh GR III or vice versa? The listing below highlights the relative strengths of the two models.

Reasons to prefer the Pentax K-3 III:

• High quality composites: Can combine several shots after pixel-shifting its sensor.
• Better video: Provides higher definition movie capture (4K/30p vs 1080/60p).
• 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.
• Easier framing: Has an optical viewfinder for image composition and settings control.
• Easier setting verification: Features an LCD display on top to control shooting parameters.
• 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 (1620k vs 1037k dots).
• Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
• Faster burst: Shoots at higher frequency (12 vs 4 flaps/sec) to capture the decisive moment.
• More flexible: Can take a variety of interchangeable lenses, including specialty optics.
• Longer lasting: Can take more shots (800 versus 200) on a single battery charge.
• Better sealing: Is weather sealed to enable shooting in dusty or wet environments.
• Easier geotagging: Features an internal GPS sensor to log localization data.
• Better studio light control: Has a PC Sync socket to connect to professional strobe lights.
• Greater peace of mind: Features a second card slot as a backup in case of memory card failure.
• Faster buffer clearing: Supports a more advanced SD data transfer standard (UHS-II vs UHS-I).
• More modern: Reflects 2 years and 1 month of technical progress since the GR III launch.

Arguments in favor of the Ricoh GR III:

• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• Ready to shoot: Comes with an integrated lens, while the K-3 III requires a separate lens.
• More compact: Is smaller (109x62mm vs 135x104mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight even though it has a lens built in (unlike the K-3 III).
• Easier travel charging: Can be conveniently charged via its USB port.
• More affordable: Was introduced at a lower price, despite coming with a built-in lens.
• More heavily discounted: Has been around for much longer (launched in February 2019).

If the count of relative strengths (bullet points above) is taken as a measure, the K-3 III is the clear winner of the match-up (18 : 7 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 Pentax K-3 III and the Ricoh GR III place the cameras among the top in their class? Find out in the latest Best DSLR Camera and Best Prime Lens Compact 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 K-3 III or the GR III perform in practice. 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 why hands-on reviews by experts are important. 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-3 III	4/5	..	3/5	..	4.5/5	..	Mar 2021	1,999	amazon.com
2.		Ricoh GR III	4/5	..	3.5/5	81/100	4/5	..	Feb 2019	899	amazon.com
3.		Fujifilm X-H1	..	+	5/5	86/100	4.5/5	4.5/5	Feb 2018	1,899	ebay.com
4.		Fujifilm X-T4	5/5	+ +	5/5	88/100	5/5	5/5	Feb 2020	1,699	ebay.com
5.		Fujifilm XF10	..	..	4/5	75/100	4/5	4.5/5	Jul 2018	499	ebay.com
6.		Nikon Z6 II	4.5/5	..	4/5	89/100	4.5/5	4.5/5	Oct 2020	1,999	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.		Panasonic ZS200	..	+ +	4.5/5	81/100	4.5/5	4.5/5	Feb 2018	799	amazon.com
9.		Pentax K-3	4/5	..	..	83/100	5/5	5/5	Oct 2013	1,299	ebay.com
10.		Pentax K-3 II	4.5/5	..	..	..	5/5	5/5	Apr 2015	1,099	ebay.com
11.		Pentax K-5 II	5/5	..	..	80/100	5/5	4.5/5	Sep 2012	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.		Pentax K-S2	4.5/5	..	..	..	5/5	4.5/5	Feb 2015	749	ebay.com
15.		Ricoh GR	5/5	..	..	79/100	4.5/5	4.5/5	Apr 2013	799	ebay.com
16.		Ricoh GR II	..	..	..	..	4.5/5	4.5/5	Jun 2015	699	ebay.com
17.		Ricoh GR IIIx	..	..	4.5/5	..	..	..	Sep 2021	999	amazon.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

Care should be taken when interpreting the review scores above, 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.

Check K-3 III price at
amazon.com
Check GR III 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 use the search menu below. Alternatively, you can follow any of the listed hyperlinks for comparisons that others found interesting.

~

Check K-3 III price at
amazon.com
Check GR III 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.