Epson R-D1 vs Pentax K-3 III

The Epson R-D1 and the Pentax K-3 III are two enthusiast cameras that were announced, respectively, in March 2004 and March 2021. The R-D1 is a rangefinder-focusing mirrorless camera, while the K-3 III is a DSLR. Both cameras are equipped with an APS-C sensor. The Epson has a resolution of 6 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

Epson R-D1		Pentax K-3 III
Rangefinder camera		Digital single lens reflex
Leica M mount lenses		Pentax K mount lenses
6 MP – APS-C sensor		25.6 MP – APS-C sensor
no Video		4K/30p Video
ISO 200-1,600		ISO 100-160,000
Optical viewfinder		Optical viewfinder
2.0" LCD – 235k dots		3.2" LCD – 1620k dots
Fixed screen (not touch-sensitive)		Fixed touchscreen
1 shutter flaps per second		12 shutter flaps per second
no shake reduction		In-body stabilization
not weather sealed		Weathersealed body
142 x 89 x 40 mm, 620 g		135 x 104 x 74 mm, 820 g

Check R-D1 offers at
ebay.com
Check K-3 III price at
amazon.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Epson R-D1 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 Epson R-D1 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 dimensions are rounded to the nearest millimeter.

The K-3 III can be obtained in two different colors (black, silver), while the R-D1 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 Pentax K-3 III is notably larger (11 percent) than the Epson R-D1. Moreover, the K-3 III is markedly heavier (32 percent) than the R-D1. It is noteworthy in this context that the K-3 III is splash and dust-proof, while the R-D1 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.

The following table provides a synthesis of the main physical specifications of the two cameras and other similar ones. 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	Street Price
1.		Epson R-D1	142 mm	89 mm	40 mm	620 g	..	n	Mar 2004	US$ 2 999	ebay.com
2.		Pentax K-3 III	135 mm	104 mm	74 mm	820 g	800	Y	Mar 2021	US$ 1 999	amazon.com
3.		Canon Rebel	142 mm	99 mm	72 mm	649 g	400	n	Aug 2003	US$ 899	ebay.com
4.		Fujifilm X-H1	140 mm	97 mm	86 mm	673 g	310	Y	Feb 2018	US$ 1 899	ebay.com
5.		Leica CL	131 mm	78 mm	45 mm	403 g	220	n	Nov 2017	US$ 2 795	ebay.com
6.		Leica M9	139 mm	80 mm	37 mm	585 g	550	n	Sep 2009	US$ 7 999	ebay.com
7.		Leica M10	139 mm	80 mm	39 mm	660 g	210	Y	Jan 2017	US$ 6 599	ebay.com
8.		Leica X Vario	133 mm	73 mm	95 mm	680 g	450	n	Jun 2013	US$ 2 849	ebay.com
9.		Leica X-U Typ 113	140 mm	79 mm	88 mm	635 g	450	Y	Jan 2016	US$ 2 949	ebay.com
10.		Nikon D40	124 mm	94 mm	64 mm	522 g	470	n	Nov 2006	US$ 499	ebay.com
11.		Nikon D50	133 mm	102 mm	76 mm	620 g	400	n	Apr 2005	US$ 749	ebay.com
12.		Nikon D70	140 mm	111 mm	78 mm	679 g	400	n	Jan 2004	US$ 999	ebay.com
13.		Nikon D70s	140 mm	111 mm	78 mm	679 g	500	n	Apr 2005	US$ 899	ebay.com
14.		Pentax K-3	131 mm	100 mm	77 mm	800 g	560	Y	Oct 2013	US$ 1 299	ebay.com
15.		Pentax K-3 II	131 mm	100 mm	77 mm	800 g	720	Y	Apr 2015	US$ 1 099	ebay.com
16.		Pentax K-70	126 mm	93 mm	74 mm	688 g	410	Y	Jun 2016	US$ 649	ebay.com
17.		Pentax KP	132 mm	101 mm	76 mm	703 g	390	Y	Jan 2017	US$ 1 099	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 K-3 III was launched at a markedly lower price (by 33 percent) than the R-D1, 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.

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 generally have larger individual pixels that offer better low-light sensitivity, provide wider dynamic range, and have richer color-depth than smaller pixels in a sensor of the same technological generation. Moreover, a large sensor camera will give the photographer more control over depth-of-field in the image and, thus, the ability to better isolate a subject from the 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 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.

Despite having a slightly smaller sensor, the K-3 III offers a higher resolution of 25.6 megapixels, compared with 6 MP of the R-D1. 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 7.85μm for the R-D1). However, it should be noted that the K-3 III is much more recent (by 17 years) than the R-D1, 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 the K-3 III has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

The resolution advantage of the Pentax K-3 III implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the K-3 III for good quality output (200 dots per inch) amounts to 31 x 20.6 inches or 78.6 x 52.4 cm, for very good quality (250 dpi) 24.8 x 16.5 inches or 62.9 x 41.9 cm, and for excellent quality (300 dpi) 20.6 x 13.8 inches or 52.4 x 35 cm. The corresponding values for the Epson R-D1 are 15 x 10 inches or 38.2 x 25.4 cm for good quality, 12 x 8 inches or 30.6 x 20.3 cm for very good quality, and 10 x 6.7 inches or 25.5 x 16.9 cm for excellent quality prints.

Unlike the R-D1, 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 Epson R-D1 has a native sensitivity range from ISO 200 to ISO 1600. The corresponding ISO settings for the Pentax K-3 III are ISO 100 to ISO 160000 (no boost).

In terms of underlying technology, the R-D1 is build around a CCD sensor, while the K-3 III uses a 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 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 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.		Epson R-D1	APS-C	6.0	3008	2000	none	21.1	10.4	564	55
2.		Pentax K-3 III	APS-C	25.6	6192	4128	4K/30p	24.2	13.7	2083	85
3.		Canon Rebel	APS-C	6.3	3072	2048	none	21.0	10.8	544	55
4.		Fujifilm X-H1	APS-C	24.0	6000	4000	4K/30p	24.0	13.3	1806	82
5.		Leica CL	APS-C	24.1	6014	4014	4K/30p	24.0	13.3	1788	82
6.		Leica M9	Full Frame	18.1	5212	3472	none	22.5	11.7	884	69
7.		Leica M10	Full Frame	23.8	5952	3992	none	24.4	13.2	2133	86
8.		Leica X Vario	APS-C	16.1	4928	3272	1080/30p	23.4	12.7	1320	78
9.		Leica X-U Typ 113	APS-C	16.1	4928	3264	1080/30p	23.8	13.0	1614	80
10.		Nikon D40	APS-C	6.0	3008	2000	none	21.0	11.0	561	56
11.		Nikon D50	APS-C	6.0	3008	2000	none	20.9	10.8	560	55
12.		Nikon D70	APS-C	6.0	3008	2000	none	20.4	10.3	529	50
13.		Nikon D70s	APS-C	6.0	3008	2000	none	20.4	10.3	529	50
14.		Pentax K-3	APS-C	24.1	6016	4000	1080/60i	23.7	13.4	1216	80
15.		Pentax K-3 II	APS-C	24.1	6016	4000	1080/60i	23.6	13.6	1106	80
16.		Pentax K-70	APS-C	24.0	6000	4000	1080/60i	23.8	13.1	1639	80
17.		Pentax KP	APS-C	24.1	6016	4000	1080/60i	23.9	13.2	1699	81
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 K-3 III indeed provides for movie recording, while the R-D1 does not. The highest resolution format that the K-3 III can use is 4K/30p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a range of features. The R-D1 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 following table reports on some other key feature differences and similarities of the Epson R-D1, 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.		Epson R-D1	optical	n	2.0 / 235	fixed	n	1/2000s	1.0/s	n	n
2.		Pentax K-3 III	optical	Y	3.2 / 1620	fixed	Y	1/8000s	12.0/s	n	Y
3.		Canon Rebel	optical	n	1.8 / 118	fixed	n	1/4000s	2.5/s	Y	n
4.		Fujifilm X-H1	3690	Y	3.0 / 1040	full-flex	Y	1/8000s	14.0/s	n	Y
5.		Leica CL	2360	Y	3.0 / 1040	fixed	Y	1/8000s	10.0/s	n	n
6.		Leica M9	optical	n	2.5 / 230	fixed	n	1/4000s	2.0/s	n	n
7.		Leica M10	optical	n	3.0 / 1037	fixed	n	1/4000s	5.0/s	n	n
8.		Leica X Vario	optional	n	3.0 / 920	fixed	n	1/2000s	5.0/s	Y	n
9.		Leica X-U Typ 113	optional	n	3.0 / 920	fixed	n	1/2000s	5.0/s	Y	n
10.		Nikon D40	optical	n	2.5 / 230	fixed	n	1/4000s	2.5/s	Y	n
11.		Nikon D50	optical	n	2.0 / 130	fixed	n	1/4000s	2.5/s	Y	n
12.		Nikon D70	optical	n	1.8 / 130	fixed	n	1/8000s	3.0/s	Y	n
13.		Nikon D70s	optical	n	2.0 / 130	fixed	n	1/8000s	3.0/s	Y	n
14.		Pentax K-3	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	Y	Y
15.		Pentax K-3 II	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	n	Y
16.		Pentax K-70	optical	n	3.0 / 921	swivel	n	1/6000s	6.0/s	Y	Y
17.		Pentax KP	optical	n	3.0 / 921	tilting	n	1/6000s	7.0/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 R-D1 has a conventional panel. Touch control can be particularly helpful, for example, for setting the focus point.

The Pentax K-3 III 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.

The R-D1 writes its imaging data to SDHC cards, while the K-3 III uses SDXC cards. The K-3 III features dual card slots, which can be very useful in case a memory card fails. In contrast, the R-D1 only has one slot. The K-3 III supports UHS-II cards on its first slot and UHS-I on its second one, while the R-D1 cannot take advantage of Ultra High Speed SD 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 Epson R-D1 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.		Epson R-D1	Y	- / -	-	-	-	-	-	-	-
2.		Pentax K-3 III	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
3.		Canon Rebel	Y	- / -	-	-	-	1.1	-	-	-
4.		Fujifilm X-H1	Y	stereo / mono	Y	-	micro	3.0	Y	-	-
5.		Leica CL	Y	stereo / mono	-	-	-	-	Y	-	-
6.		Leica M9	Y	- / -	-	-	-	2.0	-	-	-
7.		Leica M10	Y	- / -	-	-	-	-	Y	-	-
8.		Leica X Vario	Y	stereo / mono	-	-	mini	2.0	-	-	-
9.		Leica X-U Typ 113	Y	stereo / mono	-	-	-	2.0	-	-	-
10.		Nikon D40	Y	- / -	-	-	-	2.0	-	-	-
11.		Nikon D50	Y	- / -	-	-	-	2.0	-	-	-
12.		Nikon D70	Y	- / -	-	-	-	1.0	-	-	-
13.		Nikon D70s	Y	- / -	-	-	-	2.0	-	-	-
14.		Pentax K-3	Y	mono / mono	Y	Y	mini	3.0	-	-	-
15.		Pentax K-3 II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
16.		Pentax K-70	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
17.		Pentax KP	Y	stereo / mono	Y	-	-	2.0	Y	-	-

It is notable that the K-3 III offers wifi support, which can be a very convenient means to transfer image data to an off-camera location. In contrast, the R-D1 does not provide wifi capability.

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.

The K-3 III is a recent model that features in the current product line-up of Pentax. In contrast, the R-D1 has been discontinued (but can be found pre-owned on ebay). There has not been a direct replacement model for the R-D1 from Epson. Further information on the features and operation of the R-D1 and K-3 III can be found, respectively, in the Epson R-D1 Manual (free pdf) or the online Pentax K-3 III Manual.

Review summary

So how do things add up? Is the Epson R-D1 better than the Pentax K-3 III or vice versa? A synthesis of the relative strong points of each of the models is listed below.

Reasons to prefer the Epson R-D1:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Less heavy: Is lighter (by 200g or 24 percent) and hence easier to carry around.
• More heavily discounted: Has been available for much longer (launched in March 2004).

Arguments in favor of the Pentax K-3 III:

• More detail: Has more megapixels (25.6 vs 6MP), which boosts linear resolution by 106%.
• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• High quality composites: Can combine several shots after pixel-shifting its sensor.
• Broader imaging potential: Can capture not only stills but also 4K/30p video.
• Easier setting verification: Features a control panel on top to check shooting parameters.
• Larger screen: Has a bigger rear LCD (3.2" vs 2.0") for image review and settings control.
• More detailed LCD: Has a higher resolution rear screen (1620k vs 235k dots).
• Fewer buttons to press: Has a touchscreen to facilitate handling and shooting adjustments.
• Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/2000s) to freeze action.
• Faster burst: Shoots at higher frequency (12 vs 1 flaps/sec) to capture the decisive moment.
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• Better sealing: Is splash and dust sealed for shooting in inclement weather conditions.
• 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.
• 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.
• Greater peace of mind: Features a second card slot as a backup in case of memory card failure.
• Faster buffer clearing: Supports Ultra High Speed (UHS-II and UHS-I) SDXC cards.
• More affordable: Was introduced into a lower priced category (33 percent cheaper at launch).
• More modern: Reflects 17 years of technical progress since the R-D1 launch.

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 (20 : 3 points). However, the pertinence of the various camera strengths will differ across photographers, so that you might want to weigh individual camera traits according to their importance for your own imaging needs before making a camera decision. A professional sports photographer will view the differences between cameras in a way that diverges from the perspective of a street photog, and a person interested in family portraits has distinct needs from a landscape shooter. Hence, the decision which camera is best and worth buying is often a very personal one.

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 R-D1 and the K-3 III 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 why hands-on reviews by experts 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	Street Price
1.		Epson R-D1	..	..	..	..	..	..	Mar 2004	US$ 2 999	ebay.com
2.		Pentax K-3 III	4/5	..	3/5	..	4.5/5	..	Mar 2021	US$ 1 999	amazon.com
3.		Canon Rebel	..	..	..	+ +	..	..	Aug 2003	US$ 899	ebay.com
4.		Fujifilm X-H1	..	+	5/5	86/100	4.5/5	4.5/5	Feb 2018	US$ 1 899	ebay.com
5.		Leica CL	..	..	4.2/5	..	..	4/5	Nov 2017	US$ 2 795	ebay.com
6.		Leica M9	..	..	..	..	4.5/5	..	Sep 2009	US$ 7 999	ebay.com
7.		Leica M10	4.5/5	..	..	..	4/5	4.5/5	Jan 2017	US$ 6 599	ebay.com
8.		Leica X Vario	3/5	..	..	..	4/5	4/5	Jun 2013	US$ 2 849	ebay.com
9.		Leica X-U Typ 113	3.5/5	..	..	..	..	3.5/5	Jan 2016	US$ 2 949	ebay.com
10.		Nikon D40	..	81/100	..	+ +	o	4.5/5	Nov 2006	US$ 499	ebay.com
11.		Nikon D50	..	78/100	..	+ +	4/5	4.5/5	Apr 2005	US$ 749	ebay.com
12.		Nikon D70	..	..	..	+ +	..	..	Jan 2004	US$ 999	ebay.com
13.		Nikon D70s	..	..	..	..	..	5/5	Apr 2005	US$ 899	ebay.com
14.		Pentax K-3	4/5	..	..	83/100	5/5	5/5	Oct 2013	US$ 1 299	ebay.com
15.		Pentax K-3 II	4.5/5	..	..	..	5/5	5/5	Apr 2015	US$ 1 099	ebay.com
16.		Pentax K-70	4.5/5	..	4/5	79/100	4.5/5	4.5/5	Jun 2016	US$ 649	ebay.com
17.		Pentax KP	4/5	..	3/5	82/100	5/5	4.5/5	Jan 2017	US$ 1 099	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The above review scores should be interpreted with care, though. The ratings were established in reference to similarly priced cameras that were available in the market at the time of the review. Thus, a score needs to be put into the context of the launch date and the launch price 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. It should also be noted that some of the review sites have over time altered the way they render their verdicts.

Check R-D1 offers at
ebay.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 are interested in seeing how other cameras pair up, just make a corresponding selection in the search boxes below. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored.

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