Pentax 645D vs Nikon D90

The Pentax 645D and the Nikon D90 are two digital cameras that were officially introduced, respectively, in March 2010 and August 2008. Both are DSLR (Digital Single Lens Reflex) cameras that are based on a medium format (645D) and an APS-C (D90) sensor. The Pentax has a resolution of 39.5 megapixels, whereas the Nikon provides 12.2 MP.

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

Headline Specifications

Pentax 645D		Nikon D90
Digital single lens reflex		Digital single lens reflex
Pentax 645 mount lenses		Nikon F mount lenses
39.5 MP – Medium Format sensor		12.2 MP – APS-C sensor
no Video		720/24p Video
ISO 100-1,600		ISO 200-3,200 (200 - 6,400)
Optical viewfinder		Optical viewfinder
3.0" LCD – 921k dots		3.0" LCD – 920k 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		not weather sealed
800 shots per battery charge		850 shots per battery charge
156 x 117 x 119 mm, 1480 g		132 x 103 x 77 mm, 703 g

Check 645D offers at
ebay.com
Check D90 offers at
ebay.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Pentax 645D and the Nikon D90? 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 Pentax 645D and the Nikon D90. 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 Nikon D90 is notably smaller (26 percent) than the Pentax 645D. Moreover, the D90 is substantially lighter (53 percent) than the 645D. It is worth mentioning in this context that the 645D is splash and dust resistant, 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 645D gets 800 shots out of its Pentax D-LI90 battery, while the D90 can take 850 images on a single charge of its Nikon EN-EL3e 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.		Nikon D90	132 mm	103 mm	77 mm	703 g	850	n	Aug 2008	1,299	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 40D	146 mm	108 mm	74 mm	822 g	750	n	Aug 2007	1,299	ebay.com
7.		Leica S Typ 006	160 mm	120 mm	80 mm	1260 g	..	Y	Sep 2012	21,950	ebay.com
8.		Nikon D3S	160 mm	157 mm	88 mm	1240 g	4200	Y	Oct 2009	5,199	ebay.com
9.		Nikon D5	160 mm	159 mm	92 mm	1415 g	3780	Y	Jan 2016	6,499	ebay.com
10.		Nikon D80	132 mm	103 mm	77 mm	668 g	600	n	Aug 2006	999	ebay.com
11.		Nikon D300S	147 mm	115 mm	81 mm	938 g	950	Y	Jul 2009	1,799	ebay.com
12.		Nikon D810	146 mm	123 mm	82 mm	980 g	1200	Y	Jun 2014	3,299	ebay.com
13.		Nikon D850	146 mm	124 mm	79 mm	1005 g	1840	Y	Jul 2017	3,299	amazon.com
14.		Nikon D5000	127 mm	104 mm	80 mm	590 g	510	n	Apr 2009	749	ebay.com
15.		Nikon D7000	132 mm	105 mm	77 mm	780 g	1050	Y	Sep 2010	1,499	ebay.com
16.		Pentax 645Z	156 mm	117 mm	123 mm	1550 g	650	Y	Apr 2014	8,499	ebay.com
17.		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 D90 was launched at a markedly lower price (by 87 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.

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 645D features a medium format sensor and the Nikon D90 an APS-C sensor. The sensor area in the D90 is 74 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 0.79 and 1.5. The sensor in the 645D has a native 4:3 aspect ratio, while the one in the D90 offers a 3:2 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 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 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 Pentax 645D has a native sensitivity range from ISO 100 to ISO 1600. The corresponding ISO settings for the Nikon D90 are ISO 200 to ISO 3200, with the possibility to increase the ISO range to 200-6400.

In terms of underlying technology, the 645D is build around a CCD sensor, while the D90 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.

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 review, the 645D has a notably higher overall DXO score than the D90 (overall score 9 points higher), which gives it an advantage in terms of imaging quality. This 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 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.		Nikon D90	APS-C	12.2	4288	2848	720/24p	22.7	12.5	977	73
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 40D	APS-C	10.1	3888	2592	none	22.1	11.3	703	64
7.		Leica S Typ 006	Medium Format	37.5	7500	5000	none	23.9	12.2	824	76
8.		Nikon D3S	Full Frame	12.1	4256	2832	720/24p	23.5	12.0	3253	82
9.		Nikon D5	Full Frame	20.7	5588	3712	4K/30p	25.1	12.3	2343	88
10.		Nikon D80	APS-C	10.0	3872	2592	none	22.1	11.2	524	61
11.		Nikon D300S	APS-C	12.2	4288	2848	720/24p	22.5	12.2	787	70
12.		Nikon D810	Full Frame	36.2	7360	4912	1080/60p	25.7	14.8	2853	97
13.		Nikon D850	Full Frame	45.4	8256	5504	4K/30p	26.4	14.8	2660	100
14.		Nikon D5000	APS-C	12.2	4288	2848	720/24p	22.7	12.5	868	72
15.		Nikon D7000	APS-C	16.1	4928	3264	1080/24p	23.5	13.9	1167	80
16.		Pentax 645Z	Medium Format	51.1	8256	6192	1080/60i	26.0	14.7	4505	101
17.		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 D90 indeed provides for movie recording, 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 variety of features. The 645D and the D90 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 following table reports on some other key feature differences and similarities of the Pentax 645D, the Nikon D90, and comparable 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.		Nikon D90	optical	Y	3.0 / 920	fixed	n	1/4000s	4.5/s	Y	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 40D	optical	Y	3.0 / 230	fixed	n	1/8000s	6.5/s	Y	n
7.		Leica S Typ 006	optical	Y	3.0 / 922	fixed	n	1/4000s	1.5/s	n	n
8.		Nikon D3S	optical	Y	3.0 / 921	fixed	n	1/8000s	11.0/s	n	n
9.		Nikon D5	optical	Y	3.2 / 2359	fixed	Y	1/8000s	14.0/s	n	n
10.		Nikon D80	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
11.		Nikon D300S	optical	Y	3.0 / 920	fixed	n	1/8000s	7.0/s	Y	n
12.		Nikon D810	optical	Y	3.2 / 1229	fixed	n	1/8000s	5.0/s	Y	n
13.		Nikon D850	optical	Y	3.2 / 2359	tilting	Y	1/8000s	9.0/s	n	n
14.		Nikon D5000	optical	n	2.7 / 230	full-flex	n	1/4000s	4.0/s	Y	n
15.		Nikon D7000	optical	Y	3.0 / 921	fixed	n	1/8000s	6.0/s	Y	n
16.		Pentax 645Z	optical	Y	3.2 / 1037	tilting	n	1/4000s	3.0/s	n	n
17.		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.

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 645D writes its imaging data to SDXC cards, while the D90 uses SDHC 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 Pentax 645D and Nikon D90 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.		Nikon D90	Y	mono / mono	-	-	mini	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 1D X Mark II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
6.		Canon 40D	Y	- / -	-	-	-	2.0	-	-	-
7.		Leica S Typ 006	Y	- / -	-	-	mini	2.0	-	-	-
8.		Nikon D3S	Y	stereo / -	-	-	mini	2.0	-	-	-
9.		Nikon D5	Y	stereo / mono	Y	Y	mini	3.0	-	-	-
10.		Nikon D80	Y	- / -	-	-	-	2.0	-	-	-
11.		Nikon D300S	Y	stereo / mono	Y	-	mini	2.0	-	-	-
12.		Nikon D810	Y	stereo / mono	Y	Y	mini	3.0	Y	-	-
13.		Nikon D850	Y	stereo / mono	Y	Y	mini	3.0	Y	Y	Y
14.		Nikon D5000	Y	mono / mono	-	-	mini	2.0	-	-	-
15.		Nikon D7000	Y	mono / mono	Y	-	mini	2.0	-	-	-
16.		Pentax 645Z	Y	stereo / mono	Y	-	mini	3.0	-	-	-
17.		Sony A7R	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-

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 645D and the D90 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 645D and D90 can be found, respectively, in the Pentax 645D Manual (free pdf) or the online Nikon D90 Manual.

Review summary

So how do things add up? Which of the two cameras – the Pentax 645D or the Nikon D90 – 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 12.2MP) with a 76% higher linear resolution.
• 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 assessment.
• Richer colors: Generates images with noticeably better colors (1.9 bits more color depth).
• Better low-light sensitivity: Requires less light for good images (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 weather sealed to enable shooting in dusty or wet environments.
• 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: Is somewhat more recent (announced 1 year and 6 months after the D90).

Arguments in favor of the Nikon D90:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Broader imaging potential: Can capture not only stills but also 720/24p video.
• 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 will fit more readily into a bag.
• Less heavy: Has a lower weight (by 777g or 52 percent) and is thus easier to take along.
• Easier fill-in: Has a small integrated flash to brighten shadows of backlit subjects.
• 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).

If the count of individual advantages (bullet points above) is taken as a guide, the 645D is the clear winner of the match-up (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 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 Nikon D90 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 645D and the D90 in practical situations. 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 645D	5/5	..	..	..	..	..	Mar 2010	9,995	ebay.com
2.		Nikon D90	..	+ +	..	+ +	4/5	4.5/5	Aug 2008	1,299	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 40D	..	+ +	..	+ +	4.5/5	4.5/5	Aug 2007	1,299	ebay.com
7.		Leica S Typ 006	..	..	..	..	..	..	Sep 2012	21,950	ebay.com
8.		Nikon D3S	5/5	..	..	89/100	4.5/5	5/5	Oct 2009	5,199	ebay.com
9.		Nikon D5	..	..	4/5	89/100	4.5/5	5/5	Jan 2016	6,499	ebay.com
10.		Nikon D80	..	+	..	+ +	o	4.5/5	Aug 2006	999	ebay.com
11.		Nikon D300S	5/5	+ +	..	82/100	4/5	4.5/5	Jul 2009	1,799	ebay.com
12.		Nikon D810	5/5	..	5/5	86/100	5/5	4.5/5	Jun 2014	3,299	ebay.com
13.		Nikon D850	4.5/5	+ +	5/5	89/100	4.5/5	5/5	Jul 2017	3,299	amazon.com
14.		Nikon D5000	..	+ +	..	75/100	4/5	4.5/5	Apr 2009	749	ebay.com
15.		Nikon D7000	4/5	..	..	80/100	4.5/5	4.5/5	Sep 2010	1,499	ebay.com
16.		Pentax 645Z	5/5	..	3.5/5	..	4.5/5	5/5	Apr 2014	8,499	ebay.com
17.		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. Thus, a score needs to be put into the context of the launch date and the launch price of the camera, and comparisons of ratings among very different cameras or across long time periods have little meaning. Also, kindly note that some of the listed sites have over time developped their review approaches and their reporting style.

Check 645D offers at
ebay.com
Check D90 offers at
ebay.com

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.

~

Check 645D offers at
ebay.com
Check D90 offers at
ebay.com

Did you notice an error on this page? If so, please get in touch, so that we can correct the information.