Pentax K-1 vs 645D

The Pentax K-1 and the Pentax 645D are two digital cameras that were announced, respectively, in February 2016 and March 2010. Both are DSLR (Digital Single Lens Reflex) cameras that are based on a full frame (K-1) and a medium format (645D) sensor. The K-1 has a resolution of 36.2 megapixels, whereas the 645D 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

Pentax K-1		Pentax 645D
Digital single lens reflex		Digital single lens reflex
Pentax K mount lenses		Pentax 645 mount lenses
36.2 MP – Full Frame sensor		39.5 MP – Medium Format sensor
1080/60i Video		no Video
ISO 100-204,800		ISO 100-1,600
Optical viewfinder		Optical viewfinder
3.2" LCD – 1037k dots		3.0" LCD – 921k dots
Fully flexible screen (no touchscreen)		Fixed screen (not touch-sensitive)
4.4 shutter flaps per second		1.1 shutter flaps per second
In-body stabilization		Lens stabilization only
Weathersealed body		Weathersealed body
760 shots per battery charge		800 shots per battery charge
137 x 110 x 86 mm, 1010 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 Pentax K-1 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 physical size and weight of the Pentax K-1 and the Pentax 645D are illustrated 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 measures are rounded to the nearest millimeter.

The K-1 can be obtained in two different colors (black, silver), 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 notably larger (21 percent) than the Pentax K-1. Moreover, the 645D is substantially heavier (47 percent) than the K-1. 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.

The table below summarizes the key physical specs of the two cameras alongside a broader set of comparators. If you want to switch the focus of the display and review another camera pair, you can move across to the CAM-parator tool and choose from the broad selection of possible camera comparisons 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.		Pentax K-1	137 mm	110 mm	86 mm	1010 g	760	Y	Feb 2016	1,799	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.		Canon 5D Mark IV	151 mm	116 mm	76 mm	890 g	900	Y	Aug 2016	3,499	amazon.com
6.		Leica S Typ 006	160 mm	120 mm	80 mm	1260 g	..	Y	Sep 2012	21,950	ebay.com
7.		Nikon D3S	160 mm	157 mm	88 mm	1240 g	4200	Y	Oct 2009	5,199	ebay.com
8.		Nikon D500	147 mm	115 mm	81 mm	860 g	1240	Y	Jan 2016	1,999	ebay.com
9.		Olympus E-M1 II	134 mm	91 mm	67 mm	574 g	440	Y	Sep 2016	1,999	ebay.com
10.		Pentax 645Z	156 mm	117 mm	123 mm	1550 g	650	Y	Apr 2014	8,499	ebay.com
11.		Pentax K-1 II	137 mm	110 mm	86 mm	1010 g	670	Y	Feb 2018	1,999	amazon.com
12.		Pentax K-3 II	131 mm	100 mm	77 mm	800 g	720	Y	Apr 2015	1,099	ebay.com
13.		Sony A7R II	127 mm	96 mm	60 mm	625 g	290	Y	Jun 2015	3,199	ebay.com
14.		Sony A7R III	127 mm	96 mm	74 mm	650 g	650	Y	Oct 2017	3,199	ebay.com
15.		Sony A7R IIIA	127 mm	96 mm	74 mm	650 g	650	Y	Apr 2021	3,199	amazon.com
16.		Sony A99 II	143 mm	104 mm	76 mm	849 g	490	Y	Sep 2016	3,199	ebay.com
17.		Sony A850	156 mm	117 mm	82 mm	895 g	880	Y	Aug 2009	1,999	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 naturally be influenced heavily by the price. 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-1 was launched at a markedly lower price (by 82 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.

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 tend to have larger individual pixels that provide better low-light sensitivity, wider dynamic range, and richer color-depth than smaller pixel-units 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 tend to be more expensive and lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Pentax K-1 features a full frame sensor and the Pentax 645D a medium format sensor. The sensor area in the 645D is 68 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.0 and 0.79. The sensor in the K-1 has a native 3:2 aspect ratio, while the one in the 645D offers a 4:3 aspect.

In terms of chip-set technology, the K-1 uses a more advanced image processing engine (PRIME IV) than the 645D (PRIME II), with benefits for noise reduction, color accuracy, and processing speed.

With 39.5MP, the 645D offers a higher resolution than the K-1 (36.2MP), but the 645D nevertheless has larger individual pixels (pixel pitch of 6.06μm versus 4.88μm for the K-1) due to its larger sensor. However, the K-1 is a much more recent model (by 5 years and 11 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 neither of the two cameras has an anti-alias filter installed, so they are able to capture all the detail the sensor resolves.

Unlike the 645D, the K-1 has the capacity to capture high quality composite images 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-1 has a native sensitivity range from ISO 100 to ISO 204800. The corresponding ISO settings for the Pentax 645D are ISO 100 to ISO 1600 (no boost).

In terms of underlying technology, the K-1 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.

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"). Of the two cameras under review, the K-1 provides substantially higher image quality than the 645D, with an overall score that is 14 points higher. This advantage is based on 0.8 bits higher color depth, 2 EV in additional dynamic range, and 1.4 stops in additional low light sensitivity. 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 K-1	Full Frame	36.2	7360	4912	1080/60i	25.4	14.6	3280	96
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.		Canon 5D Mark IV	Full Frame	30.1	6720	4480	4K/30p	24.8	13.6	2995	91
6.		Leica S Typ 006	Medium Format	37.5	7500	5000	none	23.9	12.2	824	76
7.		Nikon D3S	Full Frame	12.1	4256	2832	720/24p	23.5	12.0	3253	82
8.		Nikon D500	APS-C	20.7	5568	3712	4K/30p	24.0	14.0	1324	83
9.		Olympus E-M1 II	Four Thirds	20.2	5184	3888	4K/30p	23.7	12.8	1312	80
10.		Pentax 645Z	Medium Format	51.1	8256	6192	1080/60i	26.0	14.7	4505	101
11.		Pentax K-1 II	Full Frame	36.2	7360	4912	1080/60i	25.1	14.0	2698	93
12.		Pentax K-3 II	APS-C	24.1	6016	4000	1080/60i	23.6	13.6	1106	80
13.		Sony A7R II	Full Frame	42.2	7952	5304	4K/30p	26.0	13.9	3434	98
14.		Sony A7R III	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
15.		Sony A7R IIIA	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
16.		Sony A99 II	Full Frame	42.2	7952	5304	4K/30p	25.4	13.4	2317	92
17.		Sony A850	Full Frame	24.4	6048	4032	none	23.8	12.2	1415	79
Note: DXO values in italics represent estimates based on sensor size and age.

Many modern cameras are not only capable of taking still images, but can also record movies. The K-1 indeed provides movie recording capabilities, while the 645D does not. The highest resolution format that the K-1 can use is 1080/60i.

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. The K-1 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 viewfinder in the K-1 offers a wider field of view (100%) than the one in the 645D (98%), so that a larger proportion of the captured image is visible in the finder. On the other hand, the viewfinder of the 645D has a higher magnification (0.78x vs 0.70x), 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 Pentax K-1 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.		Pentax K-1	optical	Y	3.2 / 1037	full-flex	n	1/8000s	4.4/s	n	Y
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.		Canon 5D Mark IV	optical	Y	3.2 / 1620	fixed	Y	1/8000s	7.0/s	n	n
6.		Leica S Typ 006	optical	Y	3.0 / 922	fixed	n	1/4000s	1.5/s	n	n
7.		Nikon D3S	optical	Y	3.0 / 921	fixed	n	1/8000s	11.0/s	n	n
8.		Nikon D500	optical	Y	3.2 / 2359	tilting	Y	1/8000s	10.0/s	n	n
9.		Olympus E-M1 II	2360	n	3.0 / 1037	swivel	Y	1/8000s	18.0/s	n	Y
10.		Pentax 645Z	optical	Y	3.2 / 1037	tilting	n	1/4000s	3.0/s	n	n
11.		Pentax K-1 II	optical	Y	3.2 / 1037	full-flex	n	1/8000s	4.4/s	n	Y
12.		Pentax K-3 II	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	n	Y
13.		Sony A7R II	2400	n	3.0 / 1229	tilting	n	1/8000s	5.0/s	n	Y
14.		Sony A7R III	3686	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
15.		Sony A7R IIIA	3686	n	3.0 / 2340	tilting	Y	1/8000s	10.0/s	n	Y
16.		Sony A99 II	2400	Y	3.0 / 1229	full-flex	n	1/8000s	12.0/s	n	Y
17.		Sony A850	optical	Y	3.0 / 922	fixed	n	1/8000s	3.0/s	n	Y
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that differentiates the K-1 and the 645D is in-body image stabilization (IBIS). The K-1 reduces the risk of handshake-induced blur with all attached lenses, while the 645D offers no blur reduction with lenses that themselves do not provide optical image stabilization.

The Pentax K-1 and the Pentax 645D 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-1 and the 645D write their files to SDXC cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails. The K-1 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 K-1 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.		Pentax K-1	Y	stereo / mono	Y	Y	micro	2.0	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.		Canon 5D Mark IV	Y	mono / mono	Y	Y	mini	3.0	Y	Y	-
6.		Leica S Typ 006	Y	- / -	-	-	mini	2.0	-	-	-
7.		Nikon D3S	Y	stereo / -	-	-	mini	2.0	-	-	-
8.		Nikon D500	Y	stereo / mono	Y	Y	mini	3.0	Y	Y	Y
9.		Olympus E-M1 II	Y	stereo / mono	Y	Y	micro	3.0	Y	-	-
10.		Pentax 645Z	Y	stereo / mono	Y	-	mini	3.0	-	-	-
11.		Pentax K-1 II	Y	stereo / mono	Y	Y	micro	2.0	Y	-	-
12.		Pentax K-3 II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
13.		Sony A7R II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
14.		Sony A7R III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
15.		Sony A7R IIIA	Y	stereo / mono	Y	Y	micro	3.2	Y	Y	Y
16.		Sony A99 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	Y
17.		Sony A850	Y	- / -	-	-	mini	2.0	-	-	-

It is notable that the K-1 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 K-1 has an internal geolocalization sensor and can record GPS coordinates in its EXIF data.

Both the K-1 and the 645D have been discontinued, but can regularly be found used on ebay. The 645D was replaced by the Pentax 645Z, while the K-1 was followed by the Pentax K-1 II. Further information on the features and operation of the K-1 and 645D can be found, respectively, in the Pentax K-1 Manual (free pdf) or the online Pentax 645D Manual.

Review summary

So what is the bottom line? Which of the two cameras – the Pentax K-1 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.

Arguments in favor of the Pentax K-1:

• High quality composites: Can combine several shots after pixel-shifting its sensor.
• Better image quality: Scores substantially higher (14 points) in the DXO overall assessment.
• More dynamic range: Captures a larger spectrum of light and dark details (2 EV of extra DR).
• Better low-light sensitivity: Requires less light for good images (1.4 stops ISO advantage).
• Better jpgs: Has a more modern image processing engine (PRIME IV vs PRIME II).
• Broader imaging potential: Can record not only still images but also 1080/60i movies.
• More complete view: Has a viewfinder with a larger field of view (100% vs 98%).
• 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 (1037k vs 921k dots).
• More flexible LCD: Has a full-flex screen for odd-angle shots in portrait or landscape orientation.
• Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
• Faster burst: Shoots at higher frequency (4.4 vs 1.1 flaps/sec) to capture the decisive moment.
• More compact: Is smaller (137x110mm vs 156x117mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 470g or 32 percent) and hence easier to carry around.
• Sharper images: Has hand-shake reducing image stabilization built-in.
• 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 (82 percent cheaper at launch).
• More modern: Reflects 5 years and 11 months of technical progress since the 645D launch.

Advantages of the Pentax 645D:

• Larger viewfinder image: Features a viewfinder with a higher magnification (0.78x vs 0.70x).
• 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 K-1 is the clear winner of the match-up (20 : 2 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 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 K-1 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 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-1 or the 645D perform in practice. User reviews, such as those found at amazon, can sometimes inform about these issues, but such feedback is often incomplete, inconsistent, and biased.

Expert reviews

This is where reviews by experts come in. The following table reports the overall ratings of the cameras as published by some of the major 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 K-1	5/5	..	..	84/100	5/5	5/5	Feb 2016	1,799	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.		Canon 5D Mark IV	4.5/5	+ +	4/5	87/100	4.5/5	4.5/5	Aug 2016	3,499	amazon.com
6.		Leica S Typ 006	..	..	..	..	..	..	Sep 2012	21,950	ebay.com
7.		Nikon D3S	5/5	..	..	89/100	4.5/5	5/5	Oct 2009	5,199	ebay.com
8.		Nikon D500	5/5	+ +	4.7/5	91/100	4.5/5	5/5	Jan 2016	1,999	ebay.com
9.		Olympus E-M1 II	5/5	+ +	5/5	85/100	4.5/5	4.5/5	Sep 2016	1,999	ebay.com
10.		Pentax 645Z	5/5	..	3.5/5	..	4.5/5	5/5	Apr 2014	8,499	ebay.com
11.		Pentax K-1 II	..	..	4.5/5	79/100	4.5/5	4.5/5	Feb 2018	1,999	amazon.com
12.		Pentax K-3 II	4.5/5	..	..	..	5/5	5/5	Apr 2015	1,099	ebay.com
13.		Sony A7R II	5/5	+ +	5/5	90/100	5/5	5/5	Jun 2015	3,199	ebay.com
14.		Sony A7R III	..	+ +	4/5	90/100	4.5/5	5/5	Oct 2017	3,199	ebay.com
15.		Sony A7R IIIA	..	+ +	4/5	90/100	4.5/5	5/5	Apr 2021	3,199	amazon.com
16.		Sony A99 II	..	..	4.5/5	85/100	4.5/5	4.5/5	Sep 2016	3,199	ebay.com
17.		Sony A850	3/5	..	..	75/100	..	4.5/5	Aug 2009	1,999	ebay.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. Hence, a score should always be seen in the context of the camera's market launch date and its price, and rating-comparisons among cameras that span long time periods or concern very differently equipped models make little sense. 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

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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