Canon M vs Pentax 645D

The Canon EOS M and the Pentax 645D are two digital cameras that were revealed to the public, respectively, in July 2012 and March 2010. The Canon M is a mirrorless interchangeable lens camera, while the 645D is a DSLR. The cameras are based on an APS-C (Canon M) and a medium format (645D) sensor. The Canon has a resolution of 17.9 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

Canon M		Pentax 645D
Mirrorless system camera		Digital single lens reflex
Canon EF-M mount lenses		Pentax 645 mount lenses
17.9 MP – APS-C sensor		39.5 MP – Medium Format sensor
1080/30p Video		no Video
ISO 100-12,800 (100 - 25,600)		ISO 100-1,600
No viewfinder, LCD framing		Optical viewfinder
3.0" LCD – 1040k dots		3.0" LCD – 921k dots
Fixed touchscreen		Fixed screen (not touch-sensitive)
4.3 shutter flaps per second		1.1 shutter flaps per second
not weather sealed		Weathersealed body
230 shots per battery charge		800 shots per battery charge
109 x 66 x 32 mm, 298 g		156 x 117 x 119 mm, 1480 g

Check Canon M offers at
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Check 645D offers at
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Going beyond this snapshot of core features and characteristics, what are the differences between the Canon EOS M 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

The side-by-side display below illustrates the physical size and weight of the Canon M and the Pentax 645D. 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.

The Canon M can be obtained in two different colors (black, white), while the 645D 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 645D is considerably larger (154 percent) than the Canon M. Moreover, the 645D is substantially heavier (397 percent) than the Canon M. It is noteworthy in this context that the 645D is splash and dust-proof, while the Canon M 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.

Concerning battery life, the Canon M gets 230 shots out of its Canon LP-E12 battery, while the 645D can take 800 images on a single charge of its Pentax D-LI90 power pack.

The adjacent table lists the principal physical characteristics of the two cameras alongside a wider set of alternatives. 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.		Canon M	109 mm	66 mm	32 mm	298 g	230	n	Jul 2012	599	ebay.com
2.		Pentax 645D	156 mm	117 mm	119 mm	1480 g	800	Y	Mar 2010	9,995	ebay.com
3.		Canon M100	108 mm	67 mm	35 mm	302 g	295	n	Aug 2017	499	ebay.com
4.		Canon M10	108 mm	67 mm	35 mm	301 g	255	n	Oct 2015	499	ebay.com
5.		Canon G7 X	103 mm	60 mm	40 mm	304 g	210	n	Sep 2014	699	ebay.com
6.		Canon G16	109 mm	76 mm	40 mm	356 g	360	n	Aug 2013	549	ebay.com
7.		Canon SL1	117 mm	91 mm	69 mm	407 g	380	n	Mar 2013	549	ebay.com
8.		Canon T5i	133 mm	100 mm	79 mm	580 g	440	n	Mar 2013	649	ebay.com
9.		Canon 1D X	158 mm	168 mm	83 mm	1551 g	1120	Y	Oct 2011	6,799	ebay.com
10.		Canon T3i	133 mm	100 mm	80 mm	570 g	440	n	Feb 2011	599	ebay.com
11.		Canon 1D Mark IV	156 mm	157 mm	80 mm	1230 g	1500	Y	Oct 2009	4,999	ebay.com
12.		Leica S Typ 006	160 mm	120 mm	80 mm	1260 g	..	Y	Sep 2012	21,950	ebay.com
13.		Nikon D3S	160 mm	157 mm	88 mm	1240 g	4200	Y	Oct 2009	5,199	ebay.com
14.		Panasonic GF6	111 mm	65 mm	38 mm	323 g	340	n	Apr 2013	499	ebay.com
15.		Panasonic G3	115 mm	84 mm	47 mm	336 g	270	n	May 2011	599	ebay.com
16.		Pentax 645Z	156 mm	117 mm	123 mm	1550 g	650	Y	Apr 2014	8,499	ebay.com
17.		Sony NEX-3N	110 mm	62 mm	35 mm	269 g	480	n	Feb 2013	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

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 Canon M was launched at a markedly lower price (by 94 percent) than the 645D, 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. Then, after the new model is out, very good deals can frequently be found on the pre-owned market.

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. 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.

Of the two cameras under consideration, the Canon M features an APS-C sensor and the Pentax 645D a medium format sensor. The sensor area in the 645D is 337 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.6 and 0.79. The sensor in the Canon M has a native 3:2 aspect ratio, while the one in the 645D offers a 4:3 aspect.

With 39.5MP, the 645D offers a higher resolution than the Canon M (17.9MP), but the 645D nevertheless has larger individual pixels (pixel pitch of 6.06μm versus 4.31μm for the Canon M) due to its larger sensor. However, the Canon M is a much more recent model (by 2 years and 4 months) than the 645D, and its sensor will have benefitted from technological advances during this time that enhance the light gathering capacity of its pixel-units. Coming back to sensor resolution, it should be mentioned that the 645D has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

The resolution advantage of the Pentax 645D implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the 645D for good quality output (200 dots per inch) amounts to 36.3 x 27.2 inches or 92.3 x 69.1 cm, for very good quality (250 dpi) 29.1 x 21.8 inches or 73.8 x 55.3 cm, and for excellent quality (300 dpi) 24.2 x 18.1 inches or 61.5 x 46.1 cm. The corresponding values for the Canon M are 25.9 x 17.3 inches or 65.8 x 43.9 cm for good quality, 20.7 x 13.8 inches or 52.7 x 35.1 cm for very good quality, and 17.3 x 11.5 inches or 43.9 x 29.3 cm for excellent quality prints.

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

The Canon EOS M has a native sensitivity range from ISO 100 to ISO 12800, which can be extended to ISO 100-25600. The corresponding ISO settings for the Pentax 645D are ISO 100 to ISO 1600 (no boost).

In terms of underlying technology, the Canon M 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.

Since 2007, DXO Mark has published sensor performance measurements that have been derived using a consistent methodology. 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. Of the two cameras under consideration, the 645D offers substantially better image quality than the Canon M (overall score 17 points higher). The advantage is based on 2.5 bits higher color depth, 1.4 EV in additional dynamic range, and 0.6 stops in additional low light sensitivity. 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.		Canon M	APS-C	17.9	5184	3456	1080/30p	22.1	11.2	827	65
2.		Pentax 645D	Medium Format	39.5	7264	5440	none	24.6	12.6	1262	82
3.		Canon M100	APS-C	24.0	6000	4000	1080/60p	23.5	12.9	1272	78
4.		Canon M10	APS-C	17.9	5184	3456	1080/30p	22.2	11.4	753	65
5.		Canon G7 X	1-inch	20.0	5472	3648	1080/60p	23.0	12.7	556	71
6.		Canon G16	1/1.7	12.0	4000	3000	1080/60p	21.0	11.7	230	54
7.		Canon SL1	APS-C	17.9	5184	3456	1080/30p	21.8	11.3	843	63
8.		Canon T5i	APS-C	17.9	5184	3456	1080/30p	21.7	11.2	681	61
9.		Canon 1D X	Full Frame	17.9	5184	3456	1080/30p	23.8	11.8	2786	82
10.		Canon T3i	APS-C	17.9	5184	3456	1080/30p	22.1	11.5	793	65
11.		Canon 1D Mark IV	APS-H	16.0	4896	3264	1080/30p	22.8	12.0	1320	74
12.		Leica S Typ 006	Medium Format	37.5	7500	5000	none	23.9	12.2	824	76
13.		Nikon D3S	Full Frame	12.1	4256	2832	720/24p	23.5	12.0	3253	82
14.		Panasonic GF6	Four Thirds	15.8	4592	3448	1080/60i	20.7	10.6	622	54
15.		Panasonic G3	Four Thirds	15.8	4592	3448	1080/60i	21.0	10.6	667	56
16.		Pentax 645Z	Medium Format	51.1	8256	6192	1080/60i	26.0	14.7	4505	101
17.		Sony NEX-3N	APS-C	16.0	4912	3264	1080/60i	22.8	12.5	1067	74

Many modern cameras cannot only take still pictures, but also record videos. The Canon M indeed provides movie recording capabilities, while the 645D does not. The highest resolution format that the Canon M can use is 1080/30p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. For example, the 645D has an optical viewfinder, which can be very useful when shooting in bright sunlight. In contrast, the Canon M relies on live view and the rear LCD for framing. The following table reports on some other key feature differences and similarities of the Canon M, the Pentax 645D, 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.		Canon M	none	n	3.0 / 1040	fixed	Y	1/4000s	4.3/s	n	n
2.		Pentax 645D	optical	Y	3.0 / 921	fixed	n	1/4000s	1.1/s	n	n
3.		Canon M100	none	n	3.0 / 1040	tilting	Y	1/4000s	6.1/s	Y	n
4.		Canon M10	none	n	3.0 / 1040	tilting	Y	1/4000s	4.6/s	Y	n
5.		Canon G7 X	none	n	3.0 / 1040	tilting	Y	1/2000s	6.5/s	Y	Y
6.		Canon G16	optical	n	3.0 / 922	fixed	n	1/4000s	2.2/s	Y	Y
7.		Canon SL1	optical	n	3.0 / 1040	fixed	Y	1/4000s	4.9/s	Y	n
8.		Canon T5i	optical	n	3.0 / 1040	swivel	Y	1/4000s	5.0/s	Y	n
9.		Canon 1D X	optical	Y	3.2 / 1040	fixed	n	1/8000s	14.0/s	n	n
10.		Canon T3i	optical	n	3.0 / 1040	swivel	n	1/4000s	3.7/s	Y	n
11.		Canon 1D Mark IV	optical	Y	3.0 / 920	fixed	n	1/8000s	10.0/s	n	n
12.		Leica S Typ 006	optical	Y	3.0 / 922	fixed	n	1/4000s	1.5/s	n	n
13.		Nikon D3S	optical	Y	3.0 / 921	fixed	n	1/8000s	11.0/s	n	n
14.		Panasonic GF6	none	n	3.0 / 1040	tilting	Y	1/4000s	4.2/s	Y	n
15.		Panasonic G3	1440	n	3.0 / 460	swivel	Y	1/4000s	4.0/s	Y	n
16.		Pentax 645Z	optical	Y	3.2 / 1037	tilting	n	1/4000s	3.0/s	n	n
17.		Sony NEX-3N	optional	n	3.0 / 460	tilting	n	1/4000s	4.0/s	Y	n
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 Canon M has a touchscreen, while the 645D has a conventional panel. Touch control can be particularly helpful, for example, for setting the focus point.

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.

Concerning the storage of imaging data, both the Canon M and the 645D write their files to SDXC cards. The 645D features dual card slots, which can be very useful in case a memory card fails. In contrast, the Canon M only has one slot. The Canon M supports UHS-I cards (Ultra High Speed data transfer of up to 104 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 Canon EOS M 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.		Canon M	Y	stereo / mono	Y	-	mini	2.0	-	-	-
2.		Pentax 645D	Y	stereo / -	-	-	-	2.0	-	-	-
3.		Canon M100	-	stereo / mono	-	-	micro	2.0	Y	Y	Y
4.		Canon M10	-	stereo / mono	-	-	mini	2.0	Y	Y	-
5.		Canon G7 X	-	stereo / mono	-	-	micro	2.0	Y	Y	-
6.		Canon G16	Y	stereo / mono	-	-	mini	2.0	Y	-	-
7.		Canon SL1	Y	mono / mono	Y	-	mini	2.0	-	-	-
8.		Canon T5i	Y	stereo / mono	Y	-	mini	2.0	-	-	-
9.		Canon 1D X	Y	mono / -	Y	-	mini	2.0	-	-	-
10.		Canon T3i	Y	mono / mono	Y	-	mini	2.0	-	-	-
11.		Canon 1D Mark IV	Y	stereo / -	Y	-	mini	2.0	-	-	-
12.		Leica S Typ 006	Y	- / -	-	-	mini	2.0	-	-	-
13.		Nikon D3S	Y	stereo / -	-	-	mini	2.0	-	-	-
14.		Panasonic GF6	-	stereo / mono	-	-	mini	2.0	Y	Y	-
15.		Panasonic G3	Y	stereo / mono	-	-	mini	2.0	-	-	-
16.		Pentax 645Z	Y	stereo / mono	Y	-	mini	3.0	-	-	-
17.		Sony NEX-3N	-	stereo / mono	-	-	micro	2.0	-	-	-

Studio photographers will appreciate that the Pentax 645D (unlike the Canon M) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the Canon M and the 645D have been discontinued, but can regularly be found used on ebay. The 645D was replaced by the Pentax 645Z, while the Canon M was followed by the Canon EOS M3. Further information on the features and operation of the Canon M and 645D can be found, respectively, in the Canon M Manual (free pdf) or the online Pentax 645D Manual.

Review summary

So what conclusions can be drawn? Which of the two cameras – the Canon M or the Pentax 645D – 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 Canon EOS M:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Broader imaging potential: Can record not only still images but also 1080/30p movies.
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• More detailed LCD: Has a higher resolution rear screen (1040k vs 921k dots).
• Fewer buttons to press: Is equipped with a touch-sensitive rear screen to facilitate handling.
• Faster burst: Shoots at higher frequency (4.3 vs 1.1 flaps/sec) to capture the decisive moment.
• More compact: Is smaller (109x66mm vs 156x117mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 1182g or 80 percent) and hence easier to carry around.
• More legacy lens friendly: Can take a broad range of non-native lenses via adapters.
• Faster buffer clearing: Has an SD card interface that supports the UHS-I standard.
• More affordable: Was introduced into a lower priced category (94 percent cheaper at launch).
• More modern: Reflects 2 years and 4 months of technical progress since the 645D launch.

Arguments in favor of the Pentax 645D:

• More detail: Has more megapixels (39.5 vs 17.9MP), which boosts linear resolution by 46%.
• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• Better image quality: Scores substantially higher (17 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (2.5 bits more color depth).
• More dynamic range: Captures a broader range of light and dark details (1.4 EV of extra DR).
• Better low-light sensitivity: Can shoot in dim conditions (0.6 stops ISO advantage).
• Easier framing: Has an optical viewfinder for image composition and settings control.
• Easier setting verification: Features a control panel on top to check shooting parameters.
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• Longer lasting: Gets more shots (800 versus 230) out of a single battery charge.
• Better sealing: Is splash and dust sealed for shooting in inclement weather conditions.
• 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.
• More heavily discounted: Has been around for much longer (launched in March 2010).

If the count of individual advantages (bullet points above) is taken as a guide, the 645D emerges as the winner of the match-up (14 : 12 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 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 Canon M and the Pentax 645D 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 Canon M or the 645D perform in practice. 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.		Canon M	3/5	+	..	..	4/5	4/5	Jul 2012	599	ebay.com
2.		Pentax 645D	5/5	..	..	..	..	..	Mar 2010	9,995	ebay.com
3.		Canon M100	3/5	+	..	..	4/5	3.5/5	Aug 2017	499	ebay.com
4.		Canon M10	..	..	..	..	..	4/5	Oct 2015	499	ebay.com
5.		Canon G7 X	4/5	+ +	..	77/100	4.5/5	4.5/5	Sep 2014	699	ebay.com
6.		Canon G16	4/5	+	..	..	4.5/5	4.5/5	Aug 2013	549	ebay.com
7.		Canon SL1	4/5	+	..	78/100	4/5	4/5	Mar 2013	549	ebay.com
8.		Canon T5i	..	..	..	76/100	4.5/5	4.5/5	Mar 2013	649	ebay.com
9.		Canon 1D X	5/5	..	..	..	4.5/5	4.5/5	Oct 2011	6,799	ebay.com
10.		Canon T3i	3/5	o	..	77/100	4.5/5	4.5/5	Feb 2011	599	ebay.com
11.		Canon 1D Mark IV	5/5	..	..	89/100	..	..	Oct 2009	4,999	ebay.com
12.		Leica S Typ 006	..	..	..	..	..	..	Sep 2012	21,950	ebay.com
13.		Nikon D3S	5/5	..	..	89/100	4.5/5	5/5	Oct 2009	5,199	ebay.com
14.		Panasonic GF6	..	+ +	..	..	4.5/5	4.5/5	Apr 2013	499	ebay.com
15.		Panasonic G3	3/5	+ +	..	75/100	4.5/5	5/5	May 2011	599	ebay.com
16.		Pentax 645Z	5/5	..	3.5/5	..	4.5/5	5/5	Apr 2014	8,499	ebay.com
17.		Sony NEX-3N	3/5	..	..	..	4.5/5	4.5/5	Feb 2013	499	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. 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, please note that some of the review sites have changed their methodology and reporting over time.

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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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