Nikon D7100 vs Pentax 645Z

The Nikon D7100 and the Pentax 645Z are two digital cameras that were officially introduced, respectively, in February 2013 and April 2014. Both are DSLR (Digital Single Lens Reflex) cameras that are based on an APS-C (D7100) and a medium format (645Z) sensor. The Nikon has a resolution of 24 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 D7100		Pentax 645Z
Digital single lens reflex		Digital single lens reflex
Nikon F mount lenses		Pentax 645 mount lenses
24 MP – APS-C sensor		51.1 MP – Medium Format sensor
1080/60p Video		1080/60i Video
ISO 100-6,400 (50 - 25,600)		ISO 100-204,800
Optical viewfinder		Optical viewfinder
3.2" LCD – 1229k dots		3.2" LCD – 1037k dots
Fixed screen (not touch-sensitive)		Tilting screen (no touchscreen)
6 shutter flaps per second		3 shutter flaps per second
Weathersealed body		Weathersealed body
950 shots per battery charge		650 shots per battery charge
136 x 107 x 76 mm, 765 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 D7100 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 side-by-side display below illustrates the physical size and weight of the Nikon D7100 and the Pentax 645Z. 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 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 (25 percent) than the Nikon D7100. Moreover, the 645Z is substantially heavier (103 percent) than the D7100. 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 D7100 gets 950 shots out of its Nikon EN-EL15 battery, while the 645Z can take 650 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 D7100	136 mm	107 mm	76 mm	765 g	950	Y	Feb 2013	1,199	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 70D	139 mm	104 mm	79 mm	755 g	920	Y	Jul 2013	1,199	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 D500	147 mm	115 mm	81 mm	860 g	1240	Y	Jan 2016	1,999	ebay.com
9.		Nikon D600	141 mm	113 mm	82 mm	850 g	900	Y	Sep 2012	2,099	ebay.com
10.		Nikon D610	141 mm	113 mm	82 mm	850 g	900	Y	Oct 2013	1,999	ebay.com
11.		Nikon D750	141 mm	113 mm	78 mm	750 g	1230	Y	Sep 2014	2,299	ebay.com
12.		Nikon D3300	124 mm	98 mm	76 mm	430 g	700	n	Jan 2014	499	ebay.com
13.		Nikon D7000	132 mm	105 mm	77 mm	780 g	1050	Y	Sep 2010	1,499	ebay.com
14.		Nikon D7200	136 mm	107 mm	76 mm	765 g	1110	Y	Mar 2015	1,199	ebay.com
15.		Nikon D7500	136 mm	104 mm	73 mm	720 g	950	Y	Apr 2017	1,299	amazon.com
16.		Pentax 645D	156 mm	117 mm	119 mm	1480 g	800	Y	Mar 2010	9,995	ebay.com
17.		Sony RX10	129 mm	88 mm	102 mm	813 g	420	Y	Oct 2013	1,299	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 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 D7100 was launched at a markedly lower price (by 86 percent) than the 645Z, 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 size of the imaging sensor is a crucial determinant 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. 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 more expensive and lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Nikon D7100 features an APS-C sensor and the Pentax 645Z a medium format sensor. The sensor area in the 645Z is 292 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 D7100 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 D7100 (24MP), but the 645Z nevertheless has larger individual pixels (pixel pitch of 5.30μm versus 3.91μm for the D7100) due to its larger sensor. Moreover, the 645Z is a somewhat more recent model (by 1 year and 1 month) than the D7100, 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 neither of the two cameras has an anti-alias filter installed, so they are able to capture all the detail the 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 D7100 are 30 x 20 inches or 76.2 x 50.8 cm for good quality, 24 x 16 inches or 61 x 40.6 cm for very good quality, and 20 x 13.3 inches or 50.8 x 33.9 cm for excellent quality prints.

The Nikon D7100 has a native sensitivity range from ISO 100 to ISO 6400, which can be extended to ISO 50-25600. 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.

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 645Z offers substantially better image quality than the D7100 (overall score 18 points higher). The advantage is based on 1.8 bits higher color depth, 1 EV in additional dynamic range, and 1.8 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 D7100	APS-C	24.0	6000	4000	1080/60p	24.2	13.7	1256	83
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 70D	APS-C	20.0	5472	3648	1080/30p	22.5	11.6	926	68
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 D500	APS-C	20.7	5568	3712	4K/30p	24.0	14.0	1324	83
9.		Nikon D600	Full Frame	24.2	6016	4016	1080/30p	25.1	14.2	2980	94
10.		Nikon D610	Full Frame	24.2	6016	4016	1080/30p	25.1	14.4	2925	94
11.		Nikon D750	Full Frame	24.2	6016	4016	1080/60p	24.8	14.5	2956	93
12.		Nikon D3300	APS-C	24.0	6000	4000	1080/60p	24.3	12.8	1385	82
13.		Nikon D7000	APS-C	16.1	4928	3264	1080/24p	23.5	13.9	1167	80
14.		Nikon D7200	APS-C	24.0	6000	4000	1080/60p	24.5	14.6	1333	87
15.		Nikon D7500	APS-C	20.7	5568	3712	4K/30p	24.3	14.0	1483	86
16.		Pentax 645D	Medium Format	39.5	7264	5440	none	24.6	12.6	1262	82
17.		Sony RX10	1-inch	20.0	5472	3648	1080/60p	22.9	12.6	474	69

Many modern cameras are not only capable of taking still images, but also of capturing video footage. Both cameras under consideration have a sensor with sufficiently fast read-out times for moving pictures, but the D7100 provides a higher frame rate than the 645Z. It can shoot video footage at 1080/60p, while the Pentax is limited to 1080/60i.

Feature comparison

Apart from body and sensor, cameras can and do differ across a range of features. The D7100 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 D7100 offers a wider field of view (100%) than the one in the 645Z (98%), so that a larger proportion of the captured image is visible in the finder. On the other hand, 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 following table reports on some other key feature differences and similarities of the Nikon D7100, the Pentax 645Z, 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.		Nikon D7100	optical	Y	3.2 / 1229	fixed	n	1/8000s	6.0/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 70D	optical	Y	3.0 / 1040	swivel	Y	1/8000s	7.0/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 D500	optical	Y	3.2 / 2359	tilting	Y	1/8000s	10.0/s	n	n
9.		Nikon D600	optical	Y	3.0 / 921	fixed	n	1/4000s	5.5/s	Y	n
10.		Nikon D610	optical	Y	3.2 / 921	fixed	n	1/4000s	6.0/s	Y	n
11.		Nikon D750	optical	Y	3.2 / 1229	tilting	n	1/4000s	6.0/s	Y	n
12.		Nikon D3300	optical	n	3.0 / 921	fixed	n	1/4000s	5.0/s	Y	n
13.		Nikon D7000	optical	Y	3.0 / 921	fixed	n	1/8000s	6.0/s	Y	n
14.		Nikon D7200	optical	Y	3.2 / 1229	fixed	n	1/8000s	6.0/s	Y	n
15.		Nikon D7500	optical	Y	3.2 / 922	tilting	Y	1/8000s	8.0/s	Y	n
16.		Pentax 645D	optical	Y	3.0 / 921	fixed	n	1/4000s	1.1/s	n	n
17.		Sony RX10	1440	Y	3.0 / 1229	tilting	n	1/3200s	10.0/s	Y	Y
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 D7100 has one, while the 645Z does not. While the built-in flash of the D7100 is not very powerful, it can at times be useful as a fill-in light.

The Nikon D7100 and the Pentax 645Z 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 D7100 and the 645Z write their files to SDXC cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails. Both cameras can use UHS-I cards, which provide for Ultra High Speed data transfer of up to 104 MB/s.

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 D7100 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 D7100	Y	stereo / mono	Y	Y	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 70D	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
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 D500	Y	stereo / mono	Y	Y	mini	3.0	Y	Y	Y
9.		Nikon D600	Y	mono / mono	Y	Y	mini	2.0	-	-	-
10.		Nikon D610	Y	mono / mono	Y	Y	mini	2.0	-	-	-
11.		Nikon D750	Y	stereo / mono	Y	Y	mini	2.0	Y	-	-
12.		Nikon D3300	Y	mono / mono	Y	-	mini	2.0	-	-	-
13.		Nikon D7000	Y	mono / mono	Y	-	mini	2.0	-	-	-
14.		Nikon D7200	Y	stereo / mono	Y	Y	mini	2.0	Y	Y	-
15.		Nikon D7500	Y	stereo / mono	Y	Y	mini	2.0	Y	-	Y
16.		Pentax 645D	Y	stereo / -	-	-	-	2.0	-	-	-
17.		Sony RX10	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-

It is notable that the D7100 has a headphone jack, which is not present on the 645Z This port makes it possible to attach external headphones and monitor the quality of sound during the recording process.

Studio photographers will appreciate that the Pentax 645Z (unlike the D7100) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the D7100 and the 645Z have been discontinued, but can regularly be found used on ebay. The D7100 was replaced by the Nikon D7200, while the 645Z does not have a direct successor. Further information on the features and operation of the D7100 and 645Z can be found, respectively, in the Nikon D7100 Manual (free pdf) or the online Pentax 645Z Manual.

Review summary

So what conclusions can be drawn? Which of the two cameras – the Nikon D7100 or the Pentax 645Z – has the upper hand? Is one clearly better than the other? Below is a summary of the relative strengths of each of the two contestants.

Reasons to prefer the Nikon D7100:

• Better video: Provides higher movie framerates (1080/60p versus 1080/60i).
• Better sound control: Has a headphone port that enables audio monitoring while recording.
• More complete view: Has a viewfinder with a larger field of view (100% vs 98%).
• More detailed LCD: Has a higher resolution rear screen (1229k vs 1037k dots).
• Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
• Faster burst: Shoots at higher frequency (6 vs 3 flaps/sec) to capture the decisive moment.
• More compact: Is smaller (136x107mm vs 156x117mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 785g or 51 percent) and hence easier to carry around.
• Longer lasting: Can take more shots (950 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 (86 percent cheaper at launch).
• More heavily discounted: Has been on the market for longer (launched in February 2013).

Arguments in favor of the Pentax 645Z:

• More detail: Has more megapixels (51.1 vs 24MP), which boosts linear resolution by 43%.
• Better image quality: Scores substantially higher (18 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (1.8 bits more color depth).
• More dynamic range: Captures a broader range of light and dark details (1 EV of extra DR).
• Better low-light sensitivity: Can shoot in dim conditions (1.8 stops ISO advantage).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.78x vs 0.63x).
• More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
• 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.
• More modern: Was introduced somewhat (1 year and 1 month) more recently.

If the number of relative strengths (bullet points above) is taken as a guide, the D7100 emerges as the winner of the contest (12 : 10 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 D7100 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 specs-based evaluation of cameras can be instructive in revealing their potential as photographic tools, it remains partial and cannot reveal, for example, the shooting experience and imaging performance when actually working with the D7100 or the 645Z. 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 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 D7100	5/5	+ +	..	85/100	4.5/5	4.5/5	Feb 2013	1,199	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 70D	5/5	+ +	..	83/100	4.5/5	5/5	Jul 2013	1,199	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 D500	5/5	+ +	4.7/5	91/100	4.5/5	5/5	Jan 2016	1,999	ebay.com
9.		Nikon D600	4/5	+ +	..	87/100	5/5	4.5/5	Sep 2012	2,099	ebay.com
10.		Nikon D610	4/5	+ +	..	87/100	4.5/5	4.5/5	Oct 2013	1,999	ebay.com
11.		Nikon D750	5/5	+ +	4/5	90/100	4.5/5	4.5/5	Sep 2014	2,299	ebay.com
12.		Nikon D3300	3/5	+	..	77/100	4.5/5	4.5/5	Jan 2014	499	ebay.com
13.		Nikon D7000	4/5	..	..	80/100	4.5/5	4.5/5	Sep 2010	1,499	ebay.com
14.		Nikon D7200	4/5	+ +	..	84/100	4.5/5	4.5/5	Mar 2015	1,199	ebay.com
15.		Nikon D7500	4.5/5	+ +	4.5/5	86/100	5/5	4.5/5	Apr 2017	1,299	amazon.com
16.		Pentax 645D	5/5	..	..	..	..	..	Mar 2010	9,995	ebay.com
17.		Sony RX10	5/5	+	..	80/100	4.5/5	4.5/5	Oct 2013	1,299	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. 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. 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

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