Nikon D90 vs Pentax 645D

The Nikon D90 and the Pentax 645D are two digital cameras that were announced, respectively, in August 2008 and March 2010. Both are DSLR (Digital Single Lens Reflex) cameras that are based on an APS-C (D90) 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 D90		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
720/24p Video		no Video
ISO 200-3,200 (200 - 6,400)		ISO 100-1,600
Optical viewfinder		Optical viewfinder
3.0" LCD – 920k dots		3.0" LCD – 921k dots
Fixed screen (not touch-sensitive)		Fixed screen (not touch-sensitive)
4.5 shutter flaps per second		1.1 shutter flaps per second
not weather sealed		Weathersealed body
850 shots per battery charge		800 shots per battery charge
132 x 103 x 77 mm, 703 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 Nikon D90 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 Nikon D90 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 measures 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 larger (34 percent) than the Nikon D90. Moreover, the 645D is substantially heavier (111 percent) than the D90. It is noteworthy in this context that the 645D is splash and dust-proof, while the D90 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 D90 gets 850 shots out of its Nikon EN-EL3e 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. 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.		Nikon D90	132 mm	103 mm	77 mm	703 g	850	n	Aug 2008	1,299	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 40D	146 mm	108 mm	74 mm	822 g	750	n	Aug 2007	1,299	ebay.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 D40X	124 mm	94 mm	64 mm	522 g	520	n	Mar 2007	729	ebay.com
9.		Nikon D60	126 mm	94 mm	64 mm	522 g	500	n	Jan 2008	629	ebay.com
10.		Nikon D80	132 mm	103 mm	77 mm	668 g	600	n	Aug 2006	999	ebay.com
11.		Nikon D300	147 mm	114 mm	74 mm	925 g	1000	Y	Aug 2007	1,799	ebay.com
12.		Nikon D300S	147 mm	115 mm	81 mm	938 g	950	Y	Jul 2009	1,799	ebay.com
13.		Nikon D3000	126 mm	97 mm	64 mm	536 g	500	n	Jul 2009	599	ebay.com
14.		Nikon D3100	124 mm	96 mm	75 mm	505 g	550	n	Aug 2010	599	ebay.com
15.		Nikon D5000	127 mm	104 mm	80 mm	590 g	510	n	Apr 2009	749	ebay.com
16.		Nikon D7000	132 mm	105 mm	77 mm	780 g	1050	Y	Sep 2010	1,499	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 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 D90 was launched at a markedly lower price (by 87 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. 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 Nikon D90 features an APS-C sensor and the Pentax 645D a medium format sensor. The sensor area in the 645D is 289 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 D90 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 D90 (12.2MP), but the 645D nevertheless has larger individual pixels (pixel pitch of 6.06μm versus 5.53μm for the D90) due to its larger sensor. Moreover, the 645D is a somewhat more recent model (by 1 year and 6 months) than the D90, and its sensor might 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 D90 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 D90 has a native sensitivity range from ISO 200 to ISO 3200, which can be extended to ISO 200-6400. The corresponding ISO settings for the Pentax 645D are ISO 100 to ISO 1600 (no boost).

In terms of underlying technology, the D90 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 has a markedly higher DXO score than the D90 (overall score 9 points higher), which will translate into better image quality. The advantage is based on 1.9 bits higher color depth, 0.1 EV in additional dynamic range, and 0.4 stops in additional low light sensitivity. The following table provides an overview of the physical sensor characteristics, as well as the sensor quality measurements for a selection of comparators.

Sensor Characteristics

		Camera Model	Sensor Class	Resolution (MP)	Horiz. Pixels	Vert. Pixels	Video Format	DXO Portrait	DXO Landscape	DXO Sports	DXO Overall
1.		Nikon D90	APS-C	12.2	4288	2848	720/24p	22.7	12.5	977	73
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 40D	APS-C	10.1	3888	2592	none	22.1	11.3	703	64
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 D40X	APS-C	10.0	3872	2592	none	22.4	11.4	516	63
9.		Nikon D60	APS-C	10.0	3872	2592	none	22.5	11.4	562	65
10.		Nikon D80	APS-C	10.0	3872	2592	none	22.1	11.2	524	61
11.		Nikon D300	APS-C	12.2	4288	2848	none	22.1	12.0	679	67
12.		Nikon D300S	APS-C	12.2	4288	2848	720/24p	22.5	12.2	787	70
13.		Nikon D3000	APS-C	10.0	3872	2592	none	22.3	11.1	563	62
14.		Nikon D3100	APS-C	14.2	4608	3072	1080/24p	22.5	11.3	919	67
15.		Nikon D5000	APS-C	12.2	4288	2848	720/24p	22.7	12.5	868	72
16.		Nikon D7000	APS-C	16.1	4928	3264	1080/24p	23.5	13.9	1167	80
17.		Pentax 645Z	Medium Format	51.1	8256	6192	1080/60i	26.0	14.7	4505	101

Many modern cameras are not only capable of taking still images, but can also record movies. The D90 indeed provides movie recording capabilities, while the 645D does not. The highest resolution format that the D90 can use is 720/24p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a range of features. The D90 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 645D offers a wider field of view (98%) than the one in the D90 (96%), 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 0.63x), 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 Nikon D90 and Pentax 645D 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.		Nikon D90	optical	Y	3.0 / 920	fixed	n	1/4000s	4.5/s	Y	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.		Canon 40D	optical	Y	3.0 / 230	fixed	n	1/8000s	6.5/s	Y	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 D40X	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
9.		Nikon D60	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
10.		Nikon D80	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
11.		Nikon D300	optical	Y	3.0 / 922	fixed	n	1/8000s	6.0/s	Y	n
12.		Nikon D300S	optical	Y	3.0 / 920	fixed	n	1/8000s	7.0/s	Y	n
13.		Nikon D3000	optical	n	3.0 / 230	fixed	n	1/4000s	3.0/s	Y	n
14.		Nikon D3100	optical	n	3.0 / 230	fixed	n	1/4000s	3.0/s	Y	n
15.		Nikon D5000	optical	n	2.7 / 230	full-flex	n	1/4000s	4.0/s	Y	n
16.		Nikon D7000	optical	Y	3.0 / 921	fixed	n	1/8000s	6.0/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.

One difference between the cameras concerns the presence of an on-board flash. The D90 has one, while the 645D does not. While the built-in flash of the D90 is not very powerful, it can at times be useful as a fill-in light.

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 D90 writes its imaging data to SDHC 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 D90 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 D90 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 D90	Y	mono / mono	-	-	mini	2.0	-	-	-
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 40D	Y	- / -	-	-	-	2.0	-	-	-
6.		Leica S Typ 006	Y	- / -	-	-	mini	2.0	-	-	-
7.		Nikon D3S	Y	stereo / -	-	-	mini	2.0	-	-	-
8.		Nikon D40X	Y	- / -	-	-	-	2.0	-	-	-
9.		Nikon D60	Y	- / -	-	-	-	2.0	-	-	-
10.		Nikon D80	Y	- / -	-	-	-	2.0	-	-	-
11.		Nikon D300	Y	- / -	-	-	mini	2.0	-	-	-
12.		Nikon D300S	Y	stereo / mono	Y	-	mini	2.0	-	-	-
13.		Nikon D3000	Y	- / -	-	-	-	2.0	-	-	-
14.		Nikon D3100	Y	mono / mono	-	-	mini	2.0	-	-	-
15.		Nikon D5000	Y	mono / mono	-	-	mini	2.0	-	-	-
16.		Nikon D7000	Y	mono / mono	Y	-	mini	2.0	-	-	-
17.		Pentax 645Z	Y	stereo / mono	Y	-	mini	3.0	-	-	-

Studio photographers will appreciate that the Pentax 645D (unlike the D90) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the D90 and the 645D have been discontinued, but can regularly be found used on ebay. The D90 was replaced by the Nikon D7000, while the 645D was followed by the Pentax 645Z. Further information on the features and operation of the D90 and 645D can be found, respectively, in the Nikon D90 Manual (free pdf) or the online Pentax 645D Manual.

Review summary

So what is the bottom line? Which of the two cameras – the Nikon D90 or the Pentax 645D – has the upper hand? Is one clearly better than the other? A synthesis of the relative strong points of each of the models is listed below.

Advantages of the Nikon D90:

• 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 720/24p movies.
• Faster burst: Shoots at higher frequency (4.5 vs 1.1 flaps/sec) to capture the decisive moment.
• More compact: Is smaller (132x103mm vs 156x117mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 777g or 52 percent) and hence easier to carry around.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• More affordable: Was introduced into a lower priced category (87 percent cheaper at launch).
• More heavily discounted: Has been on the market for longer (launched in August 2008).

Reasons to prefer 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 markedly higher (9 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (1.9 bits more color depth).
• Better low-light sensitivity: Can shoot in dim conditions (0.4 stops ISO advantage).
• More complete view: Has a viewfinder with a larger field of view (98% vs 96%).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.78x vs 0.63x).
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• 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 modern: Was introduced somewhat (1 year and 6 months) more recently.

If the count of relative strengths (bullet points above) is taken as a measure, the 645D is the clear winner of the contest (12 : 8 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 sports photographer will view the differences between cameras in a way that diverges from the perspective of a street photog, and a person interested in family portraits has distinct needs from a landscape 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 D90 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 D90 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 why expert reviews are important. The table below provides a synthesis of the camera assessments of some of the best known photo-gear 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 D90	..	+ +	..	+ +	4/5	4.5/5	Aug 2008	1,299	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 40D	..	+ +	..	+ +	4.5/5	4.5/5	Aug 2007	1,299	ebay.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 D40X	..	79/100	..	+ +	4/5	4/5	Mar 2007	729	ebay.com
9.		Nikon D60	..	80/100	..	+ +	4/5	4.5/5	Jan 2008	629	ebay.com
10.		Nikon D80	..	+	..	+ +	o	4.5/5	Aug 2006	999	ebay.com
11.		Nikon D300	..	+ +	..	+ +	5/5	4.5/5	Aug 2007	1,799	ebay.com
12.		Nikon D300S	5/5	+ +	..	82/100	4/5	4.5/5	Jul 2009	1,799	ebay.com
13.		Nikon D3000	..	+	..	72/100	4/5	4.5/5	Jul 2009	599	ebay.com
14.		Nikon D3100	5/5	+ +	..	72/100	4.5/5	4.5/5	Aug 2010	599	ebay.com
15.		Nikon D5000	..	+ +	..	75/100	4/5	4.5/5	Apr 2009	749	ebay.com
16.		Nikon D7000	4/5	..	..	80/100	4.5/5	4.5/5	Sep 2010	1,499	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.

Care should be taken when interpreting the review scores above, 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? If you would like to see a different side-by-side camera review, just make a corresponding selection in the search boxes below. As an alternative, you can also directly jump to any one of the listed comparisons that were previously generated by the CAM-parator tool.

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