Nikon D2Xs vs Pentax 645D

The Nikon D2Xs and the Pentax 645D are two professional cameras that were announced, respectively, in June 2006 and March 2010. Both are DSLR (Digital Single Lens Reflex) cameras that are based on an APS-C (D2Xs) and a medium format (645D) sensor. The Nikon has a resolution of 12.2 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

Nikon D2Xs		Pentax 645D
Digital single lens reflex		Digital single lens reflex
Nikon F mount lenses		Pentax 645 mount lenses
12.2 MP – APS-C sensor		39.5 MP – Medium Format sensor
no Video		no Video
ISO 100-800 (800 - 3,200)		ISO 100-1,600
Optical viewfinder		Optical viewfinder
2.5" LCD – 230k dots		3.0" LCD – 921k dots
Fixed screen (not touch-sensitive)		Fixed screen (not touch-sensitive)
5 shutter flaps per second		1.1 shutter flaps per second
Weathersealed body		Weathersealed body
3800 shots per battery charge		800 shots per battery charge
158 x 150 x 86 mm, 1252 g		156 x 117 x 119 mm, 1480 g

Check D2Xs offers at
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Going beyond this snapshot of core features and characteristics, what are the differences between the Nikon D2Xs 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 Nikon D2Xs and the Pentax 645D are illustrated 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 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 (23 percent) than the Nikon D2Xs. However, the 645D is markedly heavier (18 percent) than the D2Xs. 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 D2Xs gets 3800 shots out of its Nikon EN-EL4a battery, while the 645D can take 800 images on a single charge of its Pentax D-LI90 power pack. As can be seen in the images above, the D2Xs has a battery grip built in. This facilitates image-taking in portrait orientation and gives it additional battery power.

The table below summarizes the key physical specs of the two cameras alongside a broader set of comparators. 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.		Nikon D2Xs	158 mm	150 mm	86 mm	1252 g	3800	Y	Jun 2006	4,699	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 III	156 mm	157 mm	80 mm	1155 g	2200	Y	Feb 2007	4,499	ebay.com
4.		Canon 1D Mark IV	156 mm	157 mm	80 mm	1230 g	1500	Y	Oct 2009	4,999	ebay.com
5.		Canon 1D X	158 mm	168 mm	83 mm	1551 g	1120	Y	Oct 2011	6,799	ebay.com
6.		Leica S Typ 006	160 mm	120 mm	80 mm	1260 g	..	Y	Sep 2012	21,950	ebay.com
7.		Nikon D1	157 mm	153 mm	85 mm	1100 g	..	Y	Jun 1999	5,499	ebay.com
8.		Nikon D1H	157 mm	153 mm	85 mm	1100 g	1200	Y	Feb 2001	4,499	ebay.com
9.		Nikon D2X	158 mm	150 mm	86 mm	1252 g	3800	Y	Sep 2004	4,999	ebay.com
10.		Nikon D3	160 mm	157 mm	88 mm	1300 g	4300	Y	Aug 2007	4,999	ebay.com
11.		Nikon D3S	160 mm	157 mm	88 mm	1240 g	4200	Y	Oct 2009	5,199	ebay.com
12.		Nikon D40X	124 mm	94 mm	64 mm	522 g	520	n	Mar 2007	729	ebay.com
13.		Nikon D80	132 mm	103 mm	77 mm	668 g	600	n	Aug 2006	999	ebay.com
14.		Nikon D200	147 mm	113 mm	74 mm	920 g	400	Y	Nov 2005	1,699	ebay.com
15.		Nikon D300	147 mm	114 mm	74 mm	925 g	1000	Y	Aug 2007	1,799	ebay.com
16.		Nikon D300S	147 mm	115 mm	81 mm	938 g	950	Y	Jul 2009	1,799	ebay.com
17.		Pentax 645Z	156 mm	117 mm	123 mm	1550 g	650	Y	Apr 2014	8,499	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

Any camera decision will naturally be influenced heavily by the price. The listed launch prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The D2Xs was launched at a markedly lower price (by 53 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 size of the imaging sensor is a crucial determinant 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. 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 associated with larger, more expensive camera bodies and lenses.

Of the two cameras under consideration, the Nikon D2Xs features an APS-C sensor and the Pentax 645D a medium format sensor. The sensor area in the 645D is 290 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.5 and 0.79. The sensor in the D2Xs 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 D2Xs (12.2MP), but the 645D nevertheless has larger individual pixels (pixel pitch of 6.06μm versus 5.52μm for the D2Xs) due to its larger sensor. Moreover, the 645D is a much more recent model (by 3 years and 9 months) than the D2Xs, and its sensor will have benefitted from technological advances during this time that further 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 Nikon D2Xs are 21.4 x 14.2 inches or 54.5 x 36.2 cm for good quality, 17.2 x 11.4 inches or 43.6 x 28.9 cm for very good quality, and 14.3 x 9.5 inches or 36.3 x 24.1 cm for excellent quality prints.

The Nikon D2Xs has a native sensitivity range from ISO 100 to ISO 800, which can be extended to ISO 800-3200. The corresponding ISO settings for the Pentax 645D are ISO 100 to ISO 1600 (no boost).

In terms of underlying technology, the D2Xs 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 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 consideration, the 645D offers substantially better image quality than the D2Xs (overall score 23 points higher). The advantage is based on 2.4 bits higher color depth, 1.7 EV in additional dynamic range, and 1.4 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.		Nikon D2Xs	APS-C	12.2	4288	2848	none	22.2	10.9	489	59
2.		Pentax 645D	Medium Format	39.5	7264	5440	none	24.6	12.6	1262	82
3.		Canon 1D Mark III	APS-H	10.1	3888	2592	none	22.7	11.7	1078	71
4.		Canon 1D Mark IV	APS-H	16.0	4896	3264	1080/30p	22.8	12.0	1320	74
5.		Canon 1D X	Full Frame	17.9	5184	3456	1080/30p	23.8	11.8	2786	82
6.		Leica S Typ 006	Medium Format	37.5	7500	5000	none	23.9	12.2	824	76
7.		Nikon D1	APS-C	2.6	2000	1312	none	..	..	..	..
8.		Nikon D1H	APS-C	2.6	2000	1312	none	..	..	..	..
9.		Nikon D2X	APS-C	12.2	4288	2848	none	22.1	10.9	476	59
10.		Nikon D3	Full Frame	12.1	4256	2832	none	23.5	12.2	2290	81
11.		Nikon D3S	Full Frame	12.1	4256	2832	720/24p	23.5	12.0	3253	82
12.		Nikon D40X	APS-C	10.0	3872	2592	none	22.4	11.4	516	63
13.		Nikon D80	APS-C	10.0	3872	2592	none	22.1	11.2	524	61
14.		Nikon D200	APS-C	10.0	3872	2592	none	22.3	11.5	583	64
15.		Nikon D300	APS-C	12.2	4288	2848	none	22.1	12.0	679	67
16.		Nikon D300S	APS-C	12.2	4288	2848	720/24p	22.5	12.2	787	70
17.		Pentax 645Z	Medium Format	51.1	8256	6192	1080/60i	26.0	14.7	4505	101

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. The D2Xs 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 D2Xs 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 0.57x), 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 Nikon D2Xs 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.		Nikon D2Xs	optical	Y	2.5 / 230	fixed	n	1/8000s	5.0/s	n	n
2.		Pentax 645D	optical	Y	3.0 / 921	fixed	n	1/4000s	1.1/s	n	n
3.		Canon 1D Mark III	optical	Y	3.0 / 230	fixed	n	1/8000s	10.0/s	n	n
4.		Canon 1D Mark IV	optical	Y	3.0 / 920	fixed	n	1/8000s	10.0/s	n	n
5.		Canon 1D X	optical	Y	3.2 / 1040	fixed	n	1/8000s	14.0/s	n	n
6.		Leica S Typ 006	optical	Y	3.0 / 922	fixed	n	1/4000s	1.5/s	n	n
7.		Nikon D1	optical	Y	2.0 / 120	fixed	n	1/16000s	4.5/s	n	n
8.		Nikon D1H	optical	Y	2.0 / 120	fixed	n	1/16000s	5.0/s	n	n
9.		Nikon D2X	optical	Y	2.5 / 235	fixed	n	1/8000s	5.0/s	n	n
10.		Nikon D3	optical	Y	3.0 / 922	fixed	n	1/8000s	11.0/s	n	n
11.		Nikon D3S	optical	Y	3.0 / 921	fixed	n	1/8000s	11.0/s	n	n
12.		Nikon D40X	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
13.		Nikon D80	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
14.		Nikon D200	optical	Y	2.5 / 230	fixed	n	1/8000s	5.0/s	Y	n
15.		Nikon D300	optical	Y	3.0 / 922	fixed	n	1/8000s	6.0/s	Y	n
16.		Nikon D300S	optical	Y	3.0 / 920	fixed	n	1/8000s	7.0/s	Y	n
17.		Pentax 645Z	optical	Y	3.2 / 1037	tilting	n	1/4000s	3.0/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.

The D2Xs writes its imaging data to Compact Flash cards, while the 645D uses SDXC cards. The 645D features dual card slots, which can be very useful in case a memory card fails. In contrast, the D2Xs only has one slot.

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 Nikon D2Xs 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.		Nikon D2Xs	Y	- / -	-	-	-	2.0	-	-	-
2.		Pentax 645D	Y	stereo / -	-	-	-	2.0	-	-	-
3.		Canon 1D Mark III	Y	- / -	-	-	-	2.0	-	-	-
4.		Canon 1D Mark IV	Y	stereo / -	Y	-	mini	2.0	-	-	-
5.		Canon 1D X	Y	mono / -	Y	-	mini	2.0	-	-	-
6.		Leica S Typ 006	Y	- / -	-	-	mini	2.0	-	-	-
7.		Nikon D1	Y	- / -	-	-	-	FW	-	-	-
8.		Nikon D1H	Y	- / -	-	-	-	FW	-	-	-
9.		Nikon D2X	Y	- / -	-	-	-	2.0	-	-	-
10.		Nikon D3	Y	- / -	-	-	mini	2.0	-	-	-
11.		Nikon D3S	Y	stereo / -	-	-	mini	2.0	-	-	-
12.		Nikon D40X	Y	- / -	-	-	-	2.0	-	-	-
13.		Nikon D80	Y	- / -	-	-	-	2.0	-	-	-
14.		Nikon D200	Y	- / -	-	-	-	2.0	-	-	-
15.		Nikon D300	Y	- / -	-	-	mini	2.0	-	-	-
16.		Nikon D300S	Y	stereo / mono	Y	-	mini	2.0	-	-	-
17.		Pentax 645Z	Y	stereo / mono	Y	-	mini	3.0	-	-	-

Both cameras feature a PC Sync terminal to control professional strobe lights, which will be appreciated by studio photographers.

Both the D2Xs and the 645D have been discontinued, but can regularly be found used on ebay. The D2Xs was replaced by the Nikon D3X, while the 645D was followed by the Pentax 645Z. Further information on the features and operation of the D2Xs and 645D can be found, respectively, in the Nikon D2Xs Manual (free pdf) or the online Pentax 645D Manual.

Review summary

So what conclusions can be drawn? Is the Nikon D2Xs better than the Pentax 645D or vice versa? The listing below highlights the relative strengths of the two models.

Advantages of the Nikon D2Xs:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• More complete view: Has a viewfinder with a larger field of view (100% vs 98%).
• Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
• Faster burst: Shoots at higher frequency (5 vs 1.1 flaps/sec) to capture the decisive moment.
• Less heavy: Is lighter (by 228g or 15 percent) and hence easier to carry around.
• More portrait friendly: Features an integrated vertical grip for easier portrait shooting.
• Longer lasting: Can take more shots (3800 versus 800) on a single battery charge.
• More affordable: Was introduced into a lower priced category (53 percent cheaper at launch).
• More heavily discounted: Has been available for much longer (launched in June 2006).

Arguments in favor of the Pentax 645D:

• More detail: Has more megapixels (39.5 vs 12.2MP), which boosts linear resolution by 76%.
• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• Better image quality: Scores substantially higher (23 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (2.4 bits more color depth).
• More dynamic range: Captures a broader range of light and dark details (1.7 EV of extra DR).
• Better low-light sensitivity: Can shoot in dim conditions (1.4 stops ISO advantage).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.78x vs 0.57x).
• Larger screen: Has a bigger rear LCD (3.0" vs 2.5") for image review and settings control.
• More detailed LCD: Has a higher resolution rear screen (921k vs 230k dots).
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• More compact: Is smaller (156x117mm vs 158x150mm) and will fit more readily into a bag.
• Greater peace of mind: Features a second card slot as a backup in case of memory card failure.
• More modern: Reflects 3 years and 9 months of technical progress since the D2Xs launch.

If the number of relative strengths (bullet points above) is taken as a guide, the 645D is the clear winner of the contest (13 : 9 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 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 Nikon D2Xs 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 incomplete and does no justice, for example, to the way the D2Xs 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 hands-on reviews by experts are important. 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.		Nikon D2Xs	..	..	..	..	..	..	Jun 2006	4,699	ebay.com
2.		Pentax 645D	5/5	..	..	..	..	..	Mar 2010	9,995	ebay.com
3.		Canon 1D Mark III	..	..	..	..	..	..	Feb 2007	4,499	ebay.com
4.		Canon 1D Mark IV	5/5	..	..	89/100	..	..	Oct 2009	4,999	ebay.com
5.		Canon 1D X	5/5	..	..	..	4.5/5	4.5/5	Oct 2011	6,799	ebay.com
6.		Leica S Typ 006	..	..	..	..	..	..	Sep 2012	21,950	ebay.com
7.		Nikon D1	..	..	..	+ +	..	..	Jun 1999	5,499	ebay.com
8.		Nikon D1H	..	..	..	+ +	..	..	Feb 2001	4,499	ebay.com
9.		Nikon D2X	..	..	..	+ +	..	..	Sep 2004	4,999	ebay.com
10.		Nikon D3	..	..	..	+ +	5/5	4.5/5	Aug 2007	4,999	ebay.com
11.		Nikon D3S	5/5	..	..	89/100	4.5/5	5/5	Oct 2009	5,199	ebay.com
12.		Nikon D40X	..	79/100	..	+ +	4/5	4/5	Mar 2007	729	ebay.com
13.		Nikon D80	..	+	..	+ +	o	4.5/5	Aug 2006	999	ebay.com
14.		Nikon D200	..	+ +	..	+ +	o	..	Nov 2005	1,699	ebay.com
15.		Nikon D300	..	+ +	..	+ +	5/5	4.5/5	Aug 2007	1,799	ebay.com
16.		Nikon D300S	5/5	+ +	..	82/100	4/5	4.5/5	Jul 2009	1,799	ebay.com
17.		Pentax 645Z	5/5	..	3.5/5	..	4.5/5	5/5	Apr 2014	8,499	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The review scores listed above should be treated with care, though. The assessments were made in relation to similar cameras of the same technological generation. Hence, a score should always be seen in the context of the camera's market launch date and its price, and comparing ratings of very distinct cameras or ones that are far apart in terms of their release date 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

Did this review help to inform your camera decision process? If you would like to see a different side-by-side camera review, just use the search menu 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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