Nikon D810 vs Pentax K-3 III

The Nikon D810 and the Pentax K-3 III are two digital cameras that were announced, respectively, in June 2014 and March 2021. Both are DSLR (Digital Single Lens Reflex) cameras that are based on a full frame (D810) and an APS-C (K-3 III) sensor. The Nikon has a resolution of 36.2 megapixels, whereas the Pentax provides 25.6 MP.

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

Headline Specifications

Nikon D810		Pentax K-3 III
Digital single lens reflex		Digital single lens reflex
Nikon F mount lenses		Pentax K mount lenses
36.2 MP – Full Frame sensor		25.6 MP – APS-C sensor
1080/60p Video		4K/30p Video
ISO 64-12,800 (32 - 51,200)		ISO 100-160,000
Optical viewfinder		Optical viewfinder
3.2" LCD – 1229k dots		3.2" LCD – 1620k dots
Fixed screen (not touch-sensitive)		Fixed touchscreen
5 shutter flaps per second		12 shutter flaps per second
Lens stabilization only		In-body stabilization
Weathersealed body		Weathersealed body
1200 shots per battery charge		800 shots per battery charge
146 x 123 x 82 mm, 980 g		135 x 104 x 74 mm, 820 g

Check D810 offers at
ebay.com
Check K-3 III price at
amazon.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Nikon D810 and the Pentax K-3 III? 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 D810 and the Pentax K-3 III 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 size dimensions are rounded to the nearest millimeter.

The K-3 III can be obtained in two different colors (black, silver), while the D810 is only available in black.

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Pentax K-3 III is notably smaller (22 percent) than the Nikon D810. Moreover, the K-3 III is markedly lighter (16 percent) than the D810. 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 D810 gets 1200 shots out of its Nikon EN-EL15 battery, while the K-3 III can take 800 images on a single charge of its Pentax D-LI90 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.		Nikon D810	146 mm	123 mm	82 mm	980 g	1200	Y	Jun 2014	3,299	ebay.com
2.		Pentax K-3 III	135 mm	104 mm	74 mm	820 g	800	Y	Mar 2021	1,999	amazon.com
3.		Canon 5DS	152 mm	116 mm	76 mm	930 g	700	Y	Feb 2015	3,699	ebay.com
4.		Fujifilm X-H1	140 mm	97 mm	86 mm	673 g	310	Y	Feb 2018	1,899	ebay.com
5.		Nikon D4S	160 mm	157 mm	91 mm	1350 g	3020	Y	Feb 2014	6,499	ebay.com
6.		Nikon D600	141 mm	113 mm	82 mm	850 g	900	Y	Sep 2012	2,099	ebay.com
7.		Nikon D610	141 mm	113 mm	82 mm	850 g	900	Y	Oct 2013	1,999	ebay.com
8.		Nikon D700	147 mm	123 mm	77 mm	1074 g	1000	Y	Jul 2008	2,999	ebay.com
9.		Nikon D750	141 mm	113 mm	78 mm	750 g	1230	Y	Sep 2014	2,299	ebay.com
10.		Nikon D800	146 mm	123 mm	82 mm	1000 g	900	Y	Feb 2012	2,999	ebay.com
11.		Nikon D800E	146 mm	123 mm	82 mm	1000 g	900	Y	Feb 2012	3,299	ebay.com
12.		Nikon D850	146 mm	124 mm	79 mm	1005 g	1840	Y	Jul 2017	3,299	amazon.com
13.		Nikon Df	144 mm	110 mm	67 mm	760 g	1400	Y	Nov 2013	2,749	ebay.com
14.		Pentax K-3	131 mm	100 mm	77 mm	800 g	560	Y	Oct 2013	1,299	ebay.com
15.		Pentax K-3 II	131 mm	100 mm	77 mm	800 g	720	Y	Apr 2015	1,099	ebay.com
16.		Pentax K-70	126 mm	93 mm	74 mm	688 g	410	Y	Jun 2016	649	ebay.com
17.		Pentax KP	132 mm	101 mm	76 mm	703 g	390	Y	Jan 2017	1,099	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 K-3 III was launched at a markedly lower price (by 39 percent) than the D810, 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. Then, after the new model is out, very good deals can frequently be found on the pre-owned market.

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 associated with larger, more expensive camera bodies and lenses.

Of the two cameras under consideration, the Nikon D810 features a full frame sensor and the Pentax K-3 III an APS-C sensor. The sensor area in the K-3 III is 58 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.0 and 1.5. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

With 36.2MP, the D810 offers a higher resolution than the K-3 III (25.6MP), but the D810 nevertheless has larger individual pixels (pixel pitch of 4.88μm versus 3.76μm for the K-3 III) due to its larger sensor. However, the K-3 III is a much more recent model (by 6 years and 9 months) than the D810, and its sensor will 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 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 Nikon D810 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the D810 for good quality output (200 dots per inch) amounts to 36.8 x 24.6 inches or 93.5 x 62.4 cm, for very good quality (250 dpi) 29.4 x 19.6 inches or 74.8 x 49.9 cm, and for excellent quality (300 dpi) 24.5 x 16.4 inches or 62.3 x 41.6 cm. The corresponding values for the Pentax K-3 III are 31 x 20.6 inches or 78.6 x 52.4 cm for good quality, 24.8 x 16.5 inches or 62.9 x 41.9 cm for very good quality, and 20.6 x 13.8 inches or 52.4 x 35 cm for excellent quality prints.

Unlike the D810, the K-3 III has the capacity to capture high quality composite images (YESMP) by combining multiple shots after shifting its sensor by miniscule distances. This multi-shot, pixel-shift mode is most suitable for photography of stationary objects (landscapes, studio scenes).

The Nikon D810 has a native sensitivity range from ISO 64 to ISO 12800, which can be extended to ISO 32-51200. The corresponding ISO settings for the Pentax K-3 III are ISO 100 to ISO 160000 (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.

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. 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 D810	Full Frame	36.2	7360	4912	1080/60p	25.7	14.8	2853	97
2.		Pentax K-3 III	APS-C	25.6	6192	4128	4K/30p	24.2	13.7	2083	85
3.		Canon 5DS	Full Frame	50.3	8688	5792	1080/30p	24.7	12.4	2381	87
4.		Fujifilm X-H1	APS-C	24.0	6000	4000	4K/30p	24.0	13.3	1806	82
5.		Nikon D4S	Full Frame	16.2	4928	3280	1080/60p	24.4	13.3	3074	89
6.		Nikon D600	Full Frame	24.2	6016	4016	1080/30p	25.1	14.2	2980	94
7.		Nikon D610	Full Frame	24.2	6016	4016	1080/30p	25.1	14.4	2925	94
8.		Nikon D700	Full Frame	12.1	4256	2832	none	23.5	12.2	2303	80
9.		Nikon D750	Full Frame	24.2	6016	4016	1080/60p	24.8	14.5	2956	93
10.		Nikon D800	Full Frame	36.2	7360	4912	1080/30p	25.3	14.4	2853	95
11.		Nikon D800E	Full Frame	36.2	7360	4912	1080/30p	25.6	14.3	2979	96
12.		Nikon D850	Full Frame	45.4	8256	5504	4K/30p	26.4	14.8	2660	100
13.		Nikon Df	Full Frame	16.2	4928	3280	none	24.6	13.1	3279	89
14.		Pentax K-3	APS-C	24.1	6016	4000	1080/60i	23.7	13.4	1216	80
15.		Pentax K-3 II	APS-C	24.1	6016	4000	1080/60i	23.6	13.6	1106	80
16.		Pentax K-70	APS-C	24.0	6000	4000	1080/60i	23.8	13.1	1639	80
17.		Pentax KP	APS-C	24.1	6016	4000	1080/60i	23.9	13.2	1699	81
Note: DXO values in italics represent estimates based on sensor size and age.

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 K-3 III provides a better video resolution than the D810. It can shoot movie footage at 4K/30p, while the Nikon is limited to 1080/60p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. The D810 and the K-3 III 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 viewfinders of both cameras offer the same field of view (100%), as well as the same magnification (0.70x). The adjacent table lists some of the other core features of the Nikon D810 and Pentax K-3 III 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 D810	optical	Y	3.2 / 1229	fixed	n	1/8000s	5.0/s	Y	n
2.		Pentax K-3 III	optical	Y	3.2 / 1620	fixed	Y	1/8000s	12.0/s	n	Y
3.		Canon 5DS	optical	Y	3.2 / 1040	fixed	n	1/8000s	5.0/s	n	n
4.		Fujifilm X-H1	3690	Y	3.0 / 1040	full-flex	Y	1/8000s	14.0/s	n	Y
5.		Nikon D4S	optical	Y	3.2 / 921	fixed	n	1/8000s	11.0/s	n	n
6.		Nikon D600	optical	Y	3.0 / 921	fixed	n	1/4000s	5.5/s	Y	n
7.		Nikon D610	optical	Y	3.2 / 921	fixed	n	1/4000s	6.0/s	Y	n
8.		Nikon D700	optical	Y	3.0 / 922	fixed	n	1/8000s	8.0/s	Y	n
9.		Nikon D750	optical	Y	3.2 / 1229	tilting	n	1/4000s	6.0/s	Y	n
10.		Nikon D800	optical	Y	3.2 / 921	fixed	n	1/8000s	4.0/s	Y	n
11.		Nikon D800E	optical	Y	3.2 / 921	fixed	n	1/8000s	4.0/s	Y	n
12.		Nikon D850	optical	Y	3.2 / 2359	tilting	Y	1/8000s	9.0/s	n	n
13.		Nikon Df	optical	Y	3.2 / 921	fixed	n	1/4000s	5.5/s	n	n
14.		Pentax K-3	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	Y	Y
15.		Pentax K-3 II	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	n	Y
16.		Pentax K-70	optical	n	3.0 / 921	swivel	n	1/6000s	6.0/s	Y	Y
17.		Pentax KP	optical	n	3.0 / 921	tilting	n	1/6000s	7.0/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 D810 has one, while the K-3 III does not. While the built-in flash of the D810 is not very powerful, it can at times be useful as a fill-in light.

The Nikon D810 and the Pentax K-3 III 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.

The D810 writes its imaging data to Compact Flash or SDXC cards, while the K-3 III uses SDXC cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails. The K-3 III supports UHS-II cards (on its first slot), while the D810 can use UHS-I 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 D810 and Pentax K-3 III 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 D810	Y	stereo / mono	Y	Y	mini	3.0	Y	-	-
2.		Pentax K-3 III	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
3.		Canon 5DS	Y	mono / mono	Y	-	mini	3.0	-	-	-
4.		Fujifilm X-H1	Y	stereo / mono	Y	-	micro	3.0	Y	-	-
5.		Nikon D4S	Y	mono / mono	Y	Y	mini	2.0	-	-	-
6.		Nikon D600	Y	mono / mono	Y	Y	mini	2.0	-	-	-
7.		Nikon D610	Y	mono / mono	Y	Y	mini	2.0	-	-	-
8.		Nikon D700	Y	- / -	-	-	mini	2.0	-	-	-
9.		Nikon D750	Y	stereo / mono	Y	Y	mini	2.0	Y	-	-
10.		Nikon D800	Y	mono / mono	Y	Y	mini	3.0	-	-	-
11.		Nikon D800E	Y	mono / mono	Y	Y	mini	3.0	-	-	-
12.		Nikon D850	Y	stereo / mono	Y	Y	mini	3.0	Y	Y	Y
13.		Nikon Df	Y	- / -	-	-	mini	2.0	-	-	-
14.		Pentax K-3	Y	mono / mono	Y	Y	mini	3.0	-	-	-
15.		Pentax K-3 II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
16.		Pentax K-70	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
17.		Pentax KP	Y	stereo / mono	Y	-	-	2.0	Y	-	-

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

Travel and landscape photographers will find it useful that the K-3 III has an internal geolocalization sensor and can record GPS coordinates in its EXIF data.

The K-3 III is a recent model that features in the current product line-up of Pentax. In contrast, the D810 has been discontinued (but can be found pre-owned on ebay). As a replacement in the same line of cameras, the D810 was succeeded by the Nikon D850. Further information on the features and operation of the D810 and K-3 III can be found, respectively, in the Nikon D810 Manual (free pdf) or the online Pentax K-3 III Manual.

Review summary

So what conclusions can be drawn? Is there a clear favorite between the Nikon D810 and the Pentax K-3 III? Which camera is better? Below is a summary of the relative strengths of each of the two contestants.

Arguments in favor of the Nikon D810:

• More detail: Offers more megapixels (36.2 vs 25.6MP) with a 19% higher linear resolution.
• Longer lasting: Can take more shots (1200 versus 800) on a single battery charge.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• More heavily discounted: Has been available for much longer (launched in June 2014).

Advantages of the Pentax K-3 III:

• High quality composites: Can combine several shots after pixel-shifting its sensor.
• Better video: Provides higher definition movie capture (4K/30p vs 1080/60p).
• More detailed LCD: Has a higher resolution rear screen (1620k vs 1229k dots).
• Fewer buttons to press: Has a touchscreen to facilitate handling and shooting adjustments.
• Faster burst: Shoots at higher frequency (12 vs 5 flaps/sec) to capture the decisive moment.
• More compact: Is smaller (135x104mm vs 146x123mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 160g or 16 percent) and is thus easier to take along.
• Sharper images: Has stabilization technology built-in to reduce the impact of hand-shake.
• Easier geotagging: Features an internal GPS sensor to log localization data.
• Easier wireless transfer: Supports Bluetooth for image sharing without cables.
• Faster buffer clearing: Supports a more advanced SD data transfer standard (UHS-II vs UHS-I).
• More affordable: Was introduced into a lower priced category (39 percent cheaper at launch).
• More modern: Reflects 6 years and 9 months of technical progress since the D810 launch.

If the count of individual advantages (bullet points above) is taken as a guide, the K-3 III is the clear winner of the contest (13 : 4 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 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 D810 and the Pentax K-3 III 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 the spec-sheets of cameras can offer a general idea of their imaging potential, it says little about, for example, the shooting experience and imaging performance of the D810 and the K-3 III 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 where reviews by experts come in. 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 D810	5/5	..	5/5	86/100	5/5	4.5/5	Jun 2014	3,299	ebay.com
2.		Pentax K-3 III	4/5	..	3/5	..	4.5/5	..	Mar 2021	1,999	amazon.com
3.		Canon 5DS	..	+	..	83/100	4.5/5	4.5/5	Feb 2015	3,699	ebay.com
4.		Fujifilm X-H1	..	+	5/5	86/100	4.5/5	4.5/5	Feb 2018	1,899	ebay.com
5.		Nikon D4S	5/5	..	..	..	4.5/5	4.5/5	Feb 2014	6,499	ebay.com
6.		Nikon D600	4/5	+ +	..	87/100	5/5	4.5/5	Sep 2012	2,099	ebay.com
7.		Nikon D610	4/5	+ +	..	87/100	4.5/5	4.5/5	Oct 2013	1,999	ebay.com
8.		Nikon D700	..	89/100	..	+ +	4.5/5	4.5/5	Jul 2008	2,999	ebay.com
9.		Nikon D750	5/5	+ +	4/5	90/100	4.5/5	4.5/5	Sep 2014	2,299	ebay.com
10.		Nikon D800	5/5	+ +	..	82/100	5/5	5/5	Feb 2012	2,999	ebay.com
11.		Nikon D800E	..	..	..	84/100	5/5	5/5	Feb 2012	3,299	ebay.com
12.		Nikon D850	4.5/5	+ +	5/5	89/100	4.5/5	5/5	Jul 2017	3,299	amazon.com
13.		Nikon Df	4/5	..	..	81/100	4/5	4/5	Nov 2013	2,749	ebay.com
14.		Pentax K-3	4/5	..	..	83/100	5/5	5/5	Oct 2013	1,299	ebay.com
15.		Pentax K-3 II	4.5/5	..	..	..	5/5	5/5	Apr 2015	1,099	ebay.com
16.		Pentax K-70	4.5/5	..	4/5	79/100	4.5/5	4.5/5	Jun 2016	649	ebay.com
17.		Pentax KP	4/5	..	3/5	82/100	5/5	4.5/5	Jan 2017	1,099	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 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.

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Other camera comparisons

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