Leica S3 vs Pentax 645D

The Leica S3 and the Pentax 645D are two professional cameras that were revealed to the public, respectively, in September 2018 and March 2010. Both are DSLR (Digital Single Lens Reflex) cameras that are equipped with a medium format sensor. The Leica has a resolution of 64 megapixels, whereas the Pentax provides 39.5 MP.

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

Headline Specifications

Leica S3		Pentax 645D
Digital single lens reflex		Digital single lens reflex
Leica S mount lenses		Pentax 645 mount lenses
64 MP – Medium Format sensor		39.5 MP – Medium Format sensor
4K/24p Video		no Video
ISO 100-50,000		ISO 100-1,600
Optical viewfinder		Optical viewfinder
3.0" LCD – 922k dots		3.0" LCD – 921k dots
Fixed screen (not touch-sensitive)		Fixed screen (not touch-sensitive)
3 shutter flaps per second		1.1 shutter flaps per second
Weathersealed body		Weathersealed body
160 x 120 x 80 mm, 1260 g		156 x 117 x 119 mm, 1480 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Leica S3 and the Pentax 645D? 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 Leica S3 and the Pentax 645D 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.

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Pentax 645D is notably smaller (5 percent) than the Leica S3. However, the 645D is markedly heavier (17 percent) than the S3. 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 S3 gets .. shots out of its Leica BP-PRO1 battery, while the 645D can take 800 images on a single charge of its Pentax D-LI90 power pack.

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 (USD)	Street Price
1.		Leica S3	160 mm	120 mm	80 mm	1260 g	..	Y	Sep 2018	18,995	ebay.com
2.		Pentax 645D	156 mm	117 mm	119 mm	1480 g	800	Y	Mar 2010	9,995	ebay.com
3.		Canon 1D Mark IV	156 mm	157 mm	80 mm	1230 g	1500	Y	Oct 2009	4,999	ebay.com
4.		Canon 1D X	158 mm	168 mm	83 mm	1551 g	1120	Y	Oct 2011	6,799	ebay.com
5.		Leica M-E Typ 240	139 mm	80 mm	42 mm	680 g	500	Y	Jun 2019	3,999	ebay.com
6.		Leica M10	139 mm	80 mm	39 mm	660 g	210	Y	Jan 2017	6,595	ebay.com
7.		Leica M10-P	139 mm	80 mm	39 mm	660 g	210	Y	Aug 2018	7,995	ebay.com
8.		Leica Q2	130 mm	80 mm	92 mm	718 g	370	Y	Mar 2019	4,995	amazon.com
9.		Leica S2	160 mm	120 mm	80 mm	1410 g	..	Y	Sep 2008	22,995	ebay.com
10.		Leica S Typ 006	160 mm	120 mm	80 mm	1260 g	..	Y	Sep 2012	21,950	ebay.com
11.		Leica S-E Typ 006	160 mm	120 mm	80 mm	1260 g	..	Y	Sep 2014	16,900	ebay.com
12.		Leica S Typ 007	160 mm	120 mm	80 mm	1260 g	..	Y	Sep 2014	24,490	ebay.com
13.		Nikon D3S	160 mm	157 mm	88 mm	1240 g	4200	Y	Oct 2009	5,199	ebay.com
14.		Nikon D6	160 mm	163 mm	92 mm	1270 g	3580	Y	Feb 2020	6,499	amazon.com
15.		Pentax 645Z	156 mm	117 mm	123 mm	1550 g	650	Y	Apr 2014	8,499	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 listed launch prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The 645D was launched at a markedly lower price (by 47 percent) than the S3, which puts it into a different market segment. 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 are more costly to manufacture and tend to lead to bigger and heavier cameras and lenses.

Both cameras under consideration feature a medium format sensor, but their sensors differ slightly in size. The sensor area in the 645D is 8 percent bigger. As a result of these sensor size differences, the cameras have format factors, respectively, of 0.8 (S3) and 0.79. The sensor in the S3 has a native 3:2 aspect ratio, while the one in the 645D offers a 4:3 aspect.

Despite having a smaller sensor, the Leica S3 offers a higher resolution of 64 megapixels, compared with 39.5 MP of the Pentax 645D. 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 4.59μm versus 6.06μm for the 645D). However, it should be noted that the S3 is much more recent (by 8 years and 6 months) than the 645D, 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 resolution advantage of the Leica S3 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the S3 for good quality output (200 dots per inch) amounts to 49 x 32.7 inches or 124.5 x 83 cm, for very good quality (250 dpi) 39.2 x 26.1 inches or 99.6 x 66.4 cm, and for excellent quality (300 dpi) 32.7 x 21.8 inches or 83 x 55.3 cm. The corresponding values for the Pentax 645D are 36.3 x 27.2 inches or 92.3 x 69.1 cm for good quality, 29.1 x 21.8 inches or 73.8 x 55.3 cm for very good quality, and 24.2 x 18.1 inches or 61.5 x 46.1 cm for excellent quality prints.

The Leica S3 has a native sensitivity range from ISO 100 to ISO 50000. The corresponding ISO settings for the Pentax 645D are ISO 100 to ISO 1600 (no boost).

In terms of underlying technology, the S3 is build around a CMOS sensor, while the 645D uses a CCD 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 is based on lab testing and assigns an overall score to each camera sensor, as well as ratings for dynamic range ("DXO Landscape"), color depth ("DXO Portrait"), and low-light sensitivity ("DXO Sports"). 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.		Leica S3	Medium Format	64.0	9800	6533	4K/24p	25.6	14.4	3143	98
2.		Pentax 645D	Medium Format	39.5	7264	5440	none	24.6	12.6	1262	82
3.		Canon 1D Mark IV	APS-H	16.0	4896	3264	1080/30p	22.8	12.0	1320	74
4.		Canon 1D X	Full Frame	17.9	5184	3456	1080/30p	23.8	11.8	2786	82
5.		Leica M-E Typ 240	Full Frame	23.7	5952	3976	1080/25p	25.2	14.2	2821	94
6.		Leica M10	Full Frame	23.8	5952	3992	none	24.4	13.2	2133	86
7.		Leica M10-P	Full Frame	23.8	5952	3992	none	25.1	14.1	2739	93
8.		Leica Q2	Full Frame	46.7	8368	5584	4K/30p	26.4	13.5	2491	96
9.		Leica S2	Medium Format	37.5	7500	5000	none	23.9	12.5	2224	82
10.		Leica S Typ 006	Medium Format	37.5	7500	5000	none	23.9	12.2	824	76
11.		Leica S-E Typ 006	Medium Format	37.5	7500	5000	none	25.1	13.7	2763	93
12.		Leica S Typ 007	Medium Format	37.5	7500	5000	4K/24p	25.1	13.7	2763	93
13.		Nikon D3S	Full Frame	12.1	4256	2832	720/24p	23.5	12.0	3253	82
14.		Nikon D6	Full Frame	20.7	5568	3712	4K/30p	25.3	14.3	2886	95
15.		Pentax 645Z	Medium Format	51.1	8256	6192	1080/60i	26.0	14.7	4505	101
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 cannot only take still pictures, but also record videos. The S3 indeed provides movie recording capabilities, while the 645D does not. The highest resolution format that the S3 can use is 4K/24p.

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. The S3 and the 645D 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 (98%), but the viewfinder of the S3 has a higher magnification than the one of the 645D (0.87x vs 0.78x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The adjacent table lists some of the other core features of the Leica S3 and Pentax 645D along with similar information for a selection of comparators.

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.		Leica S3	optical	Y	3.0 / 922	fixed	n	1/4000s	3.0/s	n	n
2.		Pentax 645D	optical	Y	3.0 / 921	fixed	n	1/4000s	1.1/s	n	n
3.		Canon 1D Mark IV	optical	Y	3.0 / 920	fixed	n	1/8000s	10.0/s	n	n
4.		Canon 1D X	optical	Y	3.2 / 1040	fixed	n	1/8000s	14.0/s	n	n
5.		Leica M-E Typ 240	optical	n	3.0 / 920	fixed	n	1/4000s	3.0/s	n	n
6.		Leica M10	optical	n	3.0 / 1037	fixed	n	1/4000s	5.0/s	n	n
7.		Leica M10-P	optical	n	3.0 / 1037	fixed	Y	1/4000s	5.0/s	n	n
8.		Leica Q2	3680	n	3.0 / 1040	fixed	Y	1/2000s	10.0/s	n	Y
9.		Leica S2	optical	Y	3.0 / 460	fixed	n	1/4000s	1.5/s	n	n
10.		Leica S Typ 006	optical	Y	3.0 / 922	fixed	n	1/4000s	1.5/s	n	n
11.		Leica S-E Typ 006	optical	Y	3.0 / 922	fixed	n	1/4000s	1.5/s	n	n
12.		Leica S Typ 007	optical	Y	3.0 / 922	fixed	n	1/4000s	3.5/s	n	n
13.		Nikon D3S	optical	Y	3.0 / 921	fixed	n	1/8000s	11.0/s	n	n
14.		Nikon D6	optical	Y	3.2 / 2359	fixed	Y	1/8000s	14.0/s	n	n
15.		Pentax 645Z	optical	Y	3.2 / 1037	tilting	n	1/4000s	3.0/s	n	n
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.

The Pentax 645D 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 S3 writes its imaging data to Compact Flash or SDXC cards, while the 645D uses SDXC cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails. The S3 supports UHS-II cards (Ultra High Speed data transfer of up to 312 MB/s), while the 645D 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 Leica S3 and Pentax 645D 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.		Leica S3	Y	stereo / mono	Y	Y	mini	3.0	Y	-	-
2.		Pentax 645D	Y	stereo / -	-	-	-	2.0	-	-	-
3.		Canon 1D Mark IV	Y	stereo / -	Y	-	mini	2.0	-	-	-
4.		Canon 1D X	Y	mono / -	Y	-	mini	2.0	-	-	-
5.		Leica M-E Typ 240	Y	mono / -	-	-	-	2.0	-	-	-
6.		Leica M10	Y	- / -	-	-	-	-	Y	-	-
7.		Leica M10-P	Y	- / -	-	-	-	-	Y	-	-
8.		Leica Q2	Y	stereo / mono	-	-	-	-	Y	-	Y
9.		Leica S2	Y	- / -	-	-	mini	2.0	-	-	-
10.		Leica S Typ 006	Y	- / -	-	-	mini	2.0	-	-	-
11.		Leica S-E Typ 006	Y	- / -	-	-	mini	2.0	-	-	-
12.		Leica S Typ 007	Y	stereo / mono	Y	Y	mini	3.0	Y	-	-
13.		Nikon D3S	Y	stereo / -	-	-	mini	2.0	-	-	-
14.		Nikon D6	Y	stereo / mono	Y	Y	mini	3.1	Y	-	Y
15.		Pentax 645Z	Y	stereo / mono	Y	-	mini	3.0	-	-	-
16.		Sony RX10 IV	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-

It is notable that the S3 offers wifi support, while the 645D does not. Wifi can be a very convenient means to transfer image data to an off-camera location.

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 S3 has an internal geolocalization sensor and can record GPS coordinates in its EXIF data.

Both the S3 and the 645D have been discontinued, but can regularly be found used on ebay. The 645D was replaced by the Pentax 645Z, while the S3 does not have a direct successor. Further information on the features and operation of the S3 and 645D can be found, respectively, in the Leica S3 Manual (free pdf) or the online Pentax 645D Manual.

Review summary

So how do things add up? Is there a clear favorite between the Leica S3 and the Pentax 645D? Which camera is better? The listing below highlights the relative strengths of the two models.

Arguments in favor of the Leica S3:

• More detail: Offers more megapixels (64 vs 39.5MP) with a 30% higher linear resolution.
• Broader imaging potential: Can record not only still images but also 4K/24p movies.
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.87x vs 0.78x).
• Faster burst: Shoots at higher frequency (3 vs 1.1 flaps/sec) to capture the decisive moment.
• Less heavy: Is lighter (by 220g or 15 percent) and hence easier to carry around.
• Easier geotagging: Features an internal GPS sensor to log localization data.
• Faster data transfer: Supports a more advanced USB protocol (3.0 vs 2.0).
• Easier file upload: Has wifi built in for automatic backup or image transfer to the web.
• Faster buffer clearing: Supports Ultra High Speed (UHS-II) SDXC cards.
• More prestigious: Has the Leica luxury appeal, which ensures a high resale price.
• More modern: Reflects 8 years and 6 months of technical progress since the 645D launch.

Advantages of the Pentax 645D:

• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• More affordable: Was introduced into a lower priced category (47 percent cheaper at launch).
• More heavily discounted: Has been around for much longer (launched in March 2010).

If the number of relative strengths (bullet points above) is taken as a guide, the S3 is the clear winner of the match-up (11 : 3 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 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 Leica S3 and the Pentax 645D 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 technical specifications can provide a useful overview of the capabilities of different cameras, it remains partial and cannot reveal, for example, the shooting experience and imaging performance when actually working with the S3 or the 645D. 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 (USD)	Street Price
1.		Leica S3	..	..	..	..	..	..	Sep 2018	18,995	ebay.com
2.		Pentax 645D	5/5	..	..	..	..	..	Mar 2010	9,995	ebay.com
3.		Canon 1D Mark IV	5/5	..	..	89/100	..	..	Oct 2009	4,999	ebay.com
4.		Canon 1D X	5/5	..	..	..	4.5/5	4.5/5	Oct 2011	6,799	ebay.com
5.		Leica M-E Typ 240	..	..	..	..	..	..	Jun 2019	3,999	ebay.com
6.		Leica M10	4.5/5	..	..	..	4/5	4.5/5	Jan 2017	6,595	ebay.com
7.		Leica M10-P	..	..	3/5	..	..	4/5	Aug 2018	7,995	ebay.com
8.		Leica Q2	..	..	4.5/5	84/100	4.5/5	4/5	Mar 2019	4,995	amazon.com
9.		Leica S2	..	..	..	..	..	..	Sep 2008	22,995	ebay.com
10.		Leica S Typ 006	..	..	..	..	..	..	Sep 2012	21,950	ebay.com
11.		Leica S-E Typ 006	..	..	..	..	..	..	Sep 2014	16,900	ebay.com
12.		Leica S Typ 007	4/5	..	..	..	..	..	Sep 2014	24,490	ebay.com
13.		Nikon D3S	5/5	..	..	89/100	4.5/5	5/5	Oct 2009	5,199	ebay.com
14.		Nikon D6	..	..	4/5	..	4.5/5	4.5/5	Feb 2020	6,499	amazon.com
15.		Pentax 645Z	5/5	..	3.5/5	..	4.5/5	5/5	Apr 2014	8,499	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 review scores listed above should be treated 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. Hence, a score should always be seen in the context of the camera's market launch date and its price, and comparisons of ratings among very different cameras or across long time periods 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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