Pentax 645D vs Canon 6D

The Pentax 645D and the Canon EOS 6D are two digital cameras that were officially introduced, respectively, in March 2010 and September 2012. Both are DSLR (Digital Single Lens Reflex) cameras that are based on a medium format (645D) and a full frame (6D) sensor. The Pentax has a resolution of 39.5 megapixels, whereas the Canon provides 20 MP.

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

Headline Specifications

Pentax 645D		Canon 6D
Digital single lens reflex		Digital single lens reflex
Pentax 645 mount lenses		Canon EF mount lenses
39.5 MP – Medium Format sensor		20 MP – Full Frame sensor
no Video		1080/30p Video
ISO 100-1,600		ISO 100-25,600 (50 - 102,400)
Optical viewfinder		Optical viewfinder
3.0" LCD – 921k dots		3.0" LCD – 1040k dots
Fixed screen (not touch-sensitive)		Fixed screen (not touch-sensitive)
1.1 shutter flaps per second		4.5 shutter flaps per second
Weathersealed body		Weathersealed body
800 shots per battery charge		1090 shots per battery charge
156 x 117 x 119 mm, 1480 g		145 x 111 x 71 mm, 770 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Pentax 645D and the Canon EOS 6D? 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 645D and the Canon 6D 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 size 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 Canon 6D is notably smaller (12 percent) than the Pentax 645D. Moreover, the 6D is substantially lighter (48 percent) than the 645D. 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 645D gets 800 shots out of its Pentax D-LI90 battery, while the 6D can take 1090 images on a single charge of its Canon LP-E6 power pack.

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 645D	156 mm	117 mm	119 mm	1480 g	800	Y	Mar 2010	9,995	ebay.com
2.		Canon 6D	145 mm	111 mm	71 mm	770 g	1090	Y	Sep 2012	2,099	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.		Canon 1D X Mark II	158 mm	168 mm	83 mm	1530 g	1210	Y	Feb 2016	5,999	ebay.com
6.		Canon 5DS	152 mm	116 mm	76 mm	930 g	700	Y	Feb 2015	3,699	ebay.com
7.		Canon 6D Mark II	144 mm	111 mm	75 mm	765 g	1200	Y	Jun 2017	1,999	amazon.com
8.		Canon 7D II	149 mm	112 mm	78 mm	910 g	670	Y	Sep 2014	1,799	ebay.com
9.		Canon 70D	139 mm	104 mm	79 mm	755 g	920	Y	Jul 2013	1,199	ebay.com
10.		Leica S Typ 006	160 mm	120 mm	80 mm	1260 g	..	Y	Sep 2012	21,950	ebay.com
11.		Nikon D3S	160 mm	157 mm	88 mm	1240 g	4200	Y	Oct 2009	5,199	ebay.com
12.		Nikon D5	160 mm	159 mm	92 mm	1415 g	3780	Y	Jan 2016	6,499	ebay.com
13.		Nikon D810	146 mm	123 mm	82 mm	980 g	1200	Y	Jun 2014	3,299	ebay.com
14.		Nikon D850	146 mm	124 mm	79 mm	1005 g	1840	Y	Jul 2017	3,299	amazon.com
15.		Pentax 645Z	156 mm	117 mm	123 mm	1550 g	650	Y	Apr 2014	8,499	ebay.com
16.		Sony A7R	127 mm	94 mm	48 mm	465 g	340	Y	Oct 2013	2,299	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 listed launch prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The 6D was launched at a markedly lower price (by 79 percent) than the 645D, 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. 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. 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 tend to be associated with larger, more expensive camera bodies and lenses.

Of the two cameras under consideration, the Pentax 645D features a medium format sensor and the Canon 6D a full frame sensor. The sensor area in the 6D is 40 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 0.79 and 1.0. The sensor in the 645D has a native 4:3 aspect ratio, while the one in the 6D offers a 3:2 aspect.

With 39.5MP, the 645D offers a higher resolution than the 6D (20MP), but the 645D has smaller individual pixels (pixel pitch of 6.06μm versus 6.57μm for the 6D). Moreover, the 6D is a much more recent model (by 2 years and 6 months) than the 645D, and its sensor will have benefitted from technological advances during this time that enhance the light gathering capacity of its pixels. 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 6D are 27.4 x 18.2 inches or 69.5 x 46.3 cm for good quality, 21.9 x 14.6 inches or 55.6 x 37.1 cm for very good quality, and 18.2 x 12.2 inches or 46.3 x 30.9 cm for excellent quality prints.

The Pentax 645D has a native sensitivity range from ISO 100 to ISO 1600. The corresponding ISO settings for the Canon EOS 6D are ISO 100 to ISO 25600, with the possibility to increase the ISO range to 50-102400.

In terms of underlying technology, the 645D is build around a CCD sensor, while the 6D 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.

Since 2007, DXO Mark has published sensor performance measurements that have been derived using a consistent methodology. 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 Overall DXO ratings for the two cameras under consideration are close, suggesting that they provide similar imaging performance. 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.		Pentax 645D	Medium Format	39.5	7264	5440	none	24.6	12.6	1262	82
2.		Canon 6D	Full Frame	20.0	5472	3648	1080/30p	23.8	12.1	2340	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.		Canon 1D X Mark II	Full Frame	20.0	5472	3648	4K/60p	24.1	13.5	3207	88
6.		Canon 5DS	Full Frame	50.3	8688	5792	1080/30p	24.7	12.4	2381	87
7.		Canon 6D Mark II	Full Frame	26.0	6240	4160	1080/60p	24.4	11.9	2862	85
8.		Canon 7D II	APS-C	20.0	5472	3648	1080/60p	22.4	11.8	1082	70
9.		Canon 70D	APS-C	20.0	5472	3648	1080/30p	22.5	11.6	926	68
10.		Leica S Typ 006	Medium Format	37.5	7500	5000	none	23.9	12.2	824	76
11.		Nikon D3S	Full Frame	12.1	4256	2832	720/24p	23.5	12.0	3253	82
12.		Nikon D5	Full Frame	20.7	5588	3712	4K/30p	25.1	12.3	2343	88
13.		Nikon D810	Full Frame	36.2	7360	4912	1080/60p	25.7	14.8	2853	97
14.		Nikon D850	Full Frame	45.4	8256	5504	4K/30p	26.4	14.8	2660	100
15.		Pentax 645Z	Medium Format	51.1	8256	6192	1080/60i	26.0	14.7	4505	101
16.		Sony A7R	Full Frame	36.2	7360	4912	1080/60p	25.6	14.1	2746	95

Many modern cameras cannot only take still pictures, but also record videos. The 6D indeed provides for movie recording, while the 645D does not. The highest resolution format that the 6D can use is 1080/30p.

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. The 645D and the 6D 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 viewfinder in the 645D offers a wider field of view (98%) than the one in the 6D (97%), so that a larger proportion of the captured image is visible in the finder. In addition, the viewfinder of the 645D has a higher magnification (0.78x vs 0.71x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The table below summarizes some of the other core capabilities of the Pentax 645D and Canon 6D in connection with corresponding information for a sample of similar 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 645D	optical	Y	3.0 / 921	fixed	n	1/4000s	1.1/s	n	n
2.		Canon 6D	optical	Y	3.0 / 1040	fixed	n	1/4000s	4.5/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.		Canon 1D X Mark II	optical	Y	3.2 / 1620	fixed	Y	1/8000s	16.0/s	n	n
6.		Canon 5DS	optical	Y	3.2 / 1040	fixed	n	1/8000s	5.0/s	n	n
7.		Canon 6D Mark II	optical	Y	3.0 / 1040	swivel	Y	1/4000s	6.5/s	n	n
8.		Canon 7D II	optical	Y	3.0 / 1040	fixed	n	1/8000s	10.0/s	Y	n
9.		Canon 70D	optical	Y	3.0 / 1040	swivel	Y	1/8000s	7.0/s	Y	n
10.		Leica S Typ 006	optical	Y	3.0 / 922	fixed	n	1/4000s	1.5/s	n	n
11.		Nikon D3S	optical	Y	3.0 / 921	fixed	n	1/8000s	11.0/s	n	n
12.		Nikon D5	optical	Y	3.2 / 2359	fixed	Y	1/8000s	14.0/s	n	n
13.		Nikon D810	optical	Y	3.2 / 1229	fixed	n	1/8000s	5.0/s	Y	n
14.		Nikon D850	optical	Y	3.2 / 2359	tilting	Y	1/8000s	9.0/s	n	n
15.		Pentax 645Z	optical	Y	3.2 / 1037	tilting	n	1/4000s	3.0/s	n	n
16.		Sony A7R	2400	n	3.0 / 1230	tilting	n	1/8000s	4.0/s	n	n
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.

Concerning the storage of imaging data, both the 645D and the 6D 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 6D only has one slot. The 6D 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 Pentax 645D and Canon EOS 6D 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 645D	Y	stereo / -	-	-	-	2.0	-	-	-
2.		Canon 6D	Y	mono / mono	Y	-	mini	2.0	Y	-	-
3.		Canon 1D Mark IV	Y	stereo / -	Y	-	mini	2.0	-	-	-
4.		Canon 1D X	Y	mono / -	Y	-	mini	2.0	-	-	-
5.		Canon 1D X Mark II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
6.		Canon 5DS	Y	mono / mono	Y	-	mini	3.0	-	-	-
7.		Canon 6D Mark II	Y	stereo / mono	Y	-	mini	2.0	Y	Y	Y
8.		Canon 7D II	Y	stereo / mono	Y	Y	mini	3.0	-	-	-
9.		Canon 70D	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
10.		Leica S Typ 006	Y	- / -	-	-	mini	2.0	-	-	-
11.		Nikon D3S	Y	stereo / -	-	-	mini	2.0	-	-	-
12.		Nikon D5	Y	stereo / mono	Y	Y	mini	3.0	-	-	-
13.		Nikon D810	Y	stereo / mono	Y	Y	mini	3.0	Y	-	-
14.		Nikon D850	Y	stereo / mono	Y	Y	mini	3.0	Y	Y	Y
15.		Pentax 645Z	Y	stereo / mono	Y	-	mini	3.0	-	-	-
16.		Sony A7R	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-

It is notable that the 6D offers wifi support, which can be a very convenient means to transfer image data to an off-camera location. In contrast, the 645D does not provide wifi capability.

Studio photographers will appreciate that the Pentax 645D (unlike the 6D) 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 6D has an internal geolocalization sensor and can record GPS coordinates in its EXIF data.

Both the 645D and the 6D have been discontinued, but can regularly be found used on ebay. The 645D was replaced by the Pentax 645Z, while the 6D was followed by the Canon 6D Mark II. Further information on the features and operation of the 645D and 6D can be found, respectively, in the Pentax 645D Manual (free pdf) or the online Canon 6D Manual.

Review summary

So what is the bottom line? Which of the two cameras – the Pentax 645D or the Canon 6D – 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 645D:

• More detail: Offers more megapixels (39.5 vs 20MP) with a 38% higher linear resolution.
• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• More complete view: Has a viewfinder with a larger field of view (98% vs 97%).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.78x vs 0.71x).
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• 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 available for much longer (launched in March 2010).

Advantages of the Canon EOS 6D:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Better low-light sensitivity: Can shoot in dim conditions (0.9 stops ISO advantage).
• Broader imaging potential: Can capture not only stills but also 1080/30p video.
• More detailed LCD: Has a higher resolution rear screen (1040k vs 921k dots).
• Faster burst: Shoots at higher frequency (4.5 vs 1.1 flaps/sec) to capture the decisive moment.
• More compact: Is smaller (145x111mm vs 156x117mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 710g or 48 percent) and is thus easier to take along.
• Longer lasting: Gets more shots (1090 versus 800) out of a single battery charge.
• 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.
• Faster buffer clearing: Has an SD card interface that supports the UHS-I standard.
• More affordable: Was introduced into a lower priced category (79 percent cheaper at launch).
• More modern: Reflects 2 years and 6 months of technical progress since the 645D launch.

If the count of individual advantages (bullet points above) is taken as a guide, the 6D is the clear winner of the contest (13 : 8 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 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 645D and the Canon 6D 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 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 645D or the 6D 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 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 645D	5/5	..	..	..	..	..	Mar 2010	9,995	ebay.com
2.		Canon 6D	5/5	+ +	..	83/100	4.5/5	4.5/5	Sep 2012	2,099	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.		Canon 1D X Mark II	..	..	4.5/5	89/100	4.5/5	4.5/5	Feb 2016	5,999	ebay.com
6.		Canon 5DS	..	+	..	83/100	4.5/5	4.5/5	Feb 2015	3,699	ebay.com
7.		Canon 6D Mark II	4/5	+	4/5	80/100	4.5/5	4/5	Jun 2017	1,999	amazon.com
8.		Canon 7D II	4.5/5	+	3.5/5	84/100	4/5	4.5/5	Sep 2014	1,799	ebay.com
9.		Canon 70D	5/5	+ +	..	83/100	4.5/5	5/5	Jul 2013	1,199	ebay.com
10.		Leica S Typ 006	..	..	..	..	..	..	Sep 2012	21,950	ebay.com
11.		Nikon D3S	5/5	..	..	89/100	4.5/5	5/5	Oct 2009	5,199	ebay.com
12.		Nikon D5	..	..	4/5	89/100	4.5/5	5/5	Jan 2016	6,499	ebay.com
13.		Nikon D810	5/5	..	5/5	86/100	5/5	4.5/5	Jun 2014	3,299	ebay.com
14.		Nikon D850	4.5/5	+ +	5/5	89/100	4.5/5	5/5	Jul 2017	3,299	amazon.com
15.		Pentax 645Z	5/5	..	3.5/5	..	4.5/5	5/5	Apr 2014	8,499	ebay.com
16.		Sony A7R	5/5	+ +	..	82/100	4.5/5	5/5	Oct 2013	2,299	ebay.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. A score, therefore, has to be seen in close connection to the price and market introduction time of the camera, and rating-comparisons among cameras that span long time periods or concern very differently equipped models make little sense. It should also be noted that some of the review sites have over time altered the way they render their verdicts.

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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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