Nikon D90 vs Pentax 645Z

The Nikon D90 and the Pentax 645Z are two digital cameras that were revealed to the public, respectively, in August 2008 and April 2014. Both are DSLR (Digital Single Lens Reflex) cameras that are based on an APS-C (D90) and a medium format (645Z) sensor. The Nikon has a resolution of 12.2 megapixels, whereas the Pentax provides 51.1 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 645Z
Digital single lens reflex		Digital single lens reflex
Nikon F mount lenses		Pentax 645 mount lenses
12.2 MP – APS-C sensor		51.1 MP – Medium Format sensor
720/24p Video		1080/60i Video
ISO 200-3,200 (200 - 6,400)		ISO 100-204,800
Optical viewfinder		Optical viewfinder
3.0" LCD – 920k dots		3.2" LCD – 1037k dots
Fixed screen (not touch-sensitive)		Tilting screen (no touchscreen)
4.5 shutter flaps per second		3 shutter flaps per second
not weather sealed		Weathersealed body
850 shots per battery charge		650 shots per battery charge
132 x 103 x 77 mm, 703 g		156 x 117 x 123 mm, 1550 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 645Z? 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 D90 and the Pentax 645Z 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 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 Pentax 645Z is notably larger (34 percent) than the Nikon D90. Moreover, the 645Z is substantially heavier (120 percent) than the D90. It is noteworthy in this context that the 645Z 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 645Z can take 650 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.		Nikon D90	132 mm	103 mm	77 mm	703 g	850	n	Aug 2008	1,299	ebay.com
2.		Pentax 645Z	156 mm	117 mm	123 mm	1550 g	650	Y	Apr 2014	8,499	ebay.com
3.		Canon 5DS	152 mm	116 mm	76 mm	930 g	700	Y	Feb 2015	3,699	ebay.com
4.		Canon 5DS R	152 mm	116 mm	76 mm	930 g	700	Y	Feb 2015	3,699	ebay.com
5.		Canon 40D	146 mm	108 mm	74 mm	822 g	750	n	Aug 2007	1,299	ebay.com
6.		Hasselblad X1D	150 mm	98 mm	71 mm	725 g	..	Y	Jun 2016	8,995	ebay.com
7.		Leica SL	147 mm	104 mm	39 mm	847 g	400	Y	Oct 2015	7,450	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 645D	156 mm	117 mm	119 mm	1480 g	800	Y	Mar 2010	9,995	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 D90 was launched at a markedly lower price (by 85 percent) than the 645Z, 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.

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 are more costly to manufacture and tend to lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Nikon D90 features an APS-C sensor and the Pentax 645Z a medium format sensor. The sensor area in the 645Z is 285 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 645Z offers a 4:3 aspect.

With 51.1MP, the 645Z offers a higher resolution than the D90 (12.2MP), but the 645Z has smaller individual pixels (pixel pitch of 5.30μm versus 5.53μm for the D90). Yet, the 645Z is a much more recent model (by 5 years and 7 months) than the D90, 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 645Z has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

The resolution advantage of the Pentax 645Z implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the 645Z for good quality output (200 dots per inch) amounts to 41.3 x 31 inches or 104.9 x 78.6 cm, for very good quality (250 dpi) 33 x 24.8 inches or 83.9 x 62.9 cm, and for excellent quality (300 dpi) 27.5 x 20.6 inches or 69.9 x 52.4 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 645Z are ISO 100 to ISO 204800 (no boost).

Technology-wise, both cameras are equipped with CMOS (Complementary Metal–Oxide–Semiconductor) sensors. 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 consideration, the 645Z offers substantially better image quality than the D90 (overall score 28 points higher). The advantage is based on 3.3 bits higher color depth, 2.2 EV in additional dynamic range, and 2.2 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.		Nikon D90	APS-C	12.2	4288	2848	720/24p	22.7	12.5	977	73
2.		Pentax 645Z	Medium Format	51.1	8256	6192	1080/60i	26.0	14.7	4505	101
3.		Canon 5DS	Full Frame	50.3	8688	5792	1080/30p	24.7	12.4	2381	87
4.		Canon 5DS R	Full Frame	50.3	8688	5792	1080/30p	24.6	12.4	2308	86
5.		Canon 40D	APS-C	10.1	3888	2592	none	22.1	11.3	703	64
6.		Hasselblad X1D	Medium Format	51.3	8272	6200	1080/25p	26.2	14.8	4489	102
7.		Leica SL	Full Frame	24.0	6000	4000	4K/30p	25.0	13.4	1821	88
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 645D	Medium Format	39.5	7264	5440	none	24.6	12.6	1262	82

Many modern cameras cannot only take still pictures, but also record videos. The two cameras under consideration both have sensors whose read-out speed is fast enough to capture moving pictures, but the 645Z provides a better video resolution than the D90. It can shoot movie footage at 1080/60i, while the Nikon is limited to 720/24p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. The D90 and the 645Z 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 645Z 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 645Z 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 adjacent table lists some of the other core features of the Nikon D90 and Pentax 645Z 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 D90	optical	Y	3.0 / 920	fixed	n	1/4000s	4.5/s	Y	n
2.		Pentax 645Z	optical	Y	3.2 / 1037	tilting	n	1/4000s	3.0/s	n	n
3.		Canon 5DS	optical	Y	3.2 / 1040	fixed	n	1/8000s	5.0/s	n	n
4.		Canon 5DS R	optical	Y	3.2 / 1040	fixed	n	1/8000s	5.0/s	n	n
5.		Canon 40D	optical	Y	3.0 / 230	fixed	n	1/8000s	6.5/s	Y	n
6.		Hasselblad X1D	2360	n	3.0 / 920	fixed	Y	1/2000s	2.3/s	n	n
7.		Leica SL	4400	Y	3.0 / 1040	fixed	Y	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 645D	optical	Y	3.0 / 921	fixed	n	1/4000s	1.1/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 645Z 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 645Z 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 645Z uses SDXC cards. The 645Z features dual card slots, which can be very useful in case a memory card fails. In contrast, the D90 only has one slot. The 645Z supports UHS-I cards (Ultra High Speed data transfer of up to 104 MB/s), while the D90 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 Nikon D90 and Pentax 645Z 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 645Z	Y	stereo / mono	Y	-	mini	3.0	-	-	-
3.		Canon 5DS	Y	mono / mono	Y	-	mini	3.0	-	-	-
4.		Canon 5DS R	Y	mono / mono	Y	-	mini	3.0	-	-	-
5.		Canon 40D	Y	- / -	-	-	-	2.0	-	-	-
6.		Hasselblad X1D	Y	stereo / mono	Y	Y	mini	3.0	Y	-	-
7.		Leica SL	Y	stereo / mono	Y	Y	full	3.0	Y	-	-
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 645D	Y	stereo / -	-	-	-	2.0	-	-	-

It is notable that the 645Z has a microphone port, which can help to improve the quality of audio recordings by attaching an external microphone. The D90 does not feature such a mic input.

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

Both the D90 and the 645Z have been discontinued, but can regularly be found used on ebay. The D90 was replaced by the Nikon D7000, while the 645Z does not have a direct successor. Further information on the features and operation of the D90 and 645Z can be found, respectively, in the Nikon D90 Manual (free pdf) or the online Pentax 645Z Manual.

Review summary

So how do things add up? Which of the two cameras – the Nikon D90 or the Pentax 645Z – has the upper hand? Is one clearly better than the other? The listing below highlights the relative strengths of the two models.

Advantages of the Nikon D90:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Faster burst: Shoots at higher frequency (4.5 vs 3 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 847g or 55 percent) and hence easier to carry around.
• Longer lasting: Can take more shots (850 versus 650) on a single battery charge.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• More affordable: Was introduced into a lower priced category (85 percent cheaper at launch).
• More heavily discounted: Has been available for much longer (launched in August 2008).

Arguments in favor of the Pentax 645Z:

• More detail: Has more megapixels (51.1 vs 12.2MP), which boosts linear resolution by 100%.
• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• Better image quality: Scores substantially higher (28 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (3.3 bits more color depth).
• More dynamic range: Captures a broader range of light and dark details (2.2 EV of extra DR).
• Better low-light sensitivity: Can shoot in dim conditions (2.2 stops ISO advantage).
• Better video: Provides higher definition movie capture (1080/60i vs 720/24p).
• Better sound: Can connect to an external microphone for higher quality sound recording.
• 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).
• 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 920k dots).
• More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
• 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.
• Faster data transfer: Supports a more advanced USB protocol (3.0 vs 2.0).
• 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.
• Faster buffer clearing: Has an SD card interface that supports the UHS-I standard.
• More modern: Reflects 5 years and 7 months of technical progress since the D90 launch.

If the count of relative strengths (bullet points above) is taken as a measure, the 645Z is the clear winner of the contest (20 : 8 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 Nikon D90 and the Pentax 645Z 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 says little about, for example, the shooting experience and imaging performance of the D90 and the 645Z in practical situations. 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.		Nikon D90	..	+ +	..	+ +	4/5	4.5/5	Aug 2008	1,299	ebay.com
2.		Pentax 645Z	5/5	..	3.5/5	..	4.5/5	5/5	Apr 2014	8,499	ebay.com
3.		Canon 5DS	..	+	..	83/100	4.5/5	4.5/5	Feb 2015	3,699	ebay.com
4.		Canon 5DS R	5/5	+	..	83/100	5/5	4.5/5	Feb 2015	3,699	ebay.com
5.		Canon 40D	..	+ +	..	+ +	4.5/5	4.5/5	Aug 2007	1,299	ebay.com
6.		Hasselblad X1D	..	o	..	81/100	..	4/5	Jun 2016	8,995	ebay.com
7.		Leica SL	4/5	..	4/5	84/100	4.5/5	4/5	Oct 2015	7,450	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 645D	5/5	..	..	..	..	..	Mar 2010	9,995	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The above review scores should be interpreted with care, though. The assessments were made in relation to similar cameras of the same technological generation. Thus, a score needs to be put into the context of the launch date and the launch price 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? 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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