Pentax K-3 vs Sony A7 II

The Pentax K-3 and the Sony Alpha A7 II are two enthusiast cameras that were revealed to the public, respectively, in October 2013 and November 2014. The K-3 is a DSLR, while the A7 II is a mirrorless interchangeable lens camera. The cameras are based on an APS-C (K-3) and a full frame (A7 II) sensor. The Pentax has a resolution of 24.1 megapixels, whereas the Sony provides 24 MP.

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

Headline Specifications

Pentax K-3		Sony A7 II
Digital single lens reflex		Mirrorless system camera
Pentax K mount lenses		Sony E mount lenses
24.1 MP – APS-C sensor		24 MP – Full Frame sensor
1080/60i Video		1080/60p Video
ISO 100-51,200		ISO 100-25,600 (50 - 51,200)
Optical viewfinder		Electronic viewfinder (2400k dots)
3.2" LCD – 1037k dots		3.0" LCD – 1230k dots
Fixed screen (not touch-sensitive)		Tilting screen (no touchscreen)
8.3 shutter flaps per second		5 shutter flaps per second
In-body stabilization		In-body stabilization
Weathersealed body		Weathersealed body
560 shots per battery charge		350 shots per battery charge
131 x 100 x 77 mm, 800 g		127 x 96 x 60 mm, 599 g

Check K-3 offers at
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Check A7 II offers at
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Going beyond this snapshot of core features and characteristics, what are the differences between the Pentax K-3 and the Sony Alpha A7 II? 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

An illustration of the physical size and weight of the Pentax K-3 and the Sony A7 II is provided 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 width, height and depth measures are rounded to the nearest millimeter.

The K-3 can be obtained in two different colors (black, silver), while the A7 II 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 Sony A7 II is notably smaller (7 percent) than the Pentax K-3. Moreover, the A7 II is markedly lighter (25 percent) than the K-3. 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 K-3 gets 560 shots out of its D-LI90 battery, while the A7 II can take 350 images on a single charge of its NP-FW50 power pack. The power pack in the A7 II can be charged via the USB port, which can be very convenient when travelling.

The adjacent table lists the principal physical characteristics of the two cameras alongside a wider set of alternatives. 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 K-3	131 mm	100 mm	77 mm	800 g	560	Y	Oct 2013	1,299	ebay.com
2.		Sony A7 II	127 mm	96 mm	60 mm	599 g	350	Y	Nov 2014	1,999	ebay.com
3.		Nikon D7100	136 mm	107 mm	76 mm	765 g	950	Y	Feb 2013	1,199	ebay.com
4.		Pentax KP	132 mm	101 mm	76 mm	703 g	390	Y	Jan 2017	1,099	ebay.com
5.		Pentax K-70	126 mm	93 mm	74 mm	688 g	410	Y	Jun 2016	649	amazon.com
6.		Pentax K-S2	123 mm	91 mm	73 mm	678 g	410	Y	Feb 2015	749	ebay.com
7.		Pentax K-3 II	131 mm	100 mm	77 mm	800 g	720	Y	Apr 2015	1,099	ebay.com
8.		Pentax K-S1	121 mm	93 mm	70 mm	558 g	410	n	Aug 2014	749	ebay.com
9.		Pentax K-50	130 mm	97 mm	71 mm	650 g	410	Y	Jun 2013	599	ebay.com
10.		Pentax K-5 II	131 mm	97 mm	73 mm	760 g	740	Y	Sep 2012	1,099	ebay.com
11.		Pentax K-5	131 mm	97 mm	73 mm	760 g	740	Y	Sep 2010	1,099	ebay.com
12.		Sony A7C	124 mm	71 mm	60 mm	509 g	740	Y	Sep 2020	1,799	amazon.com
13.		Sony A9 II	129 mm	96 mm	76 mm	678 g	690	Y	Oct 2019	4,499	amazon.com
14.		Sony A7 III	127 mm	96 mm	74 mm	650 g	610	Y	Feb 2018	1,999	amazon.com
15.		Sony A7	127 mm	94 mm	48 mm	474 g	340	Y	Oct 2013	1,699	ebay.com
16.		Sony A7R	127 mm	94 mm	48 mm	465 g	340	Y	Oct 2013	2,299	ebay.com
17.		Sony A77	143 mm	104 mm	81 mm	732 g	470	Y	Aug 2011	1,399	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 K-3 was launched at a markedly lower price (by 35 percent) than the A7 II, 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. 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 are more costly to manufacture and tend to lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Pentax K-3 features an APS-C sensor and the Sony A7 II a full frame sensor. The sensor area in the A7 II is 133 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.5 and 1.0. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

Despite having a smaller sensor, the Pentax K-3 offers a higher resolution of 24.1 megapixels, compared with 24 MP of the Sony A7 II. This megapixels advantage comes at the cost of a higher pixel density and a smaller size of the individual pixel (with a pixel pitch of 3.90μm versus 5.97μm for the A7 II). Moreover, it should be noted that the A7 II is a somewhat more recent model (by 1 year and 1 month) than the K-3, 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 K-3 has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

The A7 II has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

The Pentax K-3 has a native sensitivity range from ISO 100 to ISO 51200. The corresponding ISO settings for the Sony Alpha A7 II are ISO 100 to ISO 25600, with the possibility to increase the ISO range to 50-51200.

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 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 A7 II has a markedly higher DXO score than the K-3 (overall score 10 points higher), which will translate into better image quality. The advantage is based on 1.2 bits higher color depth, 0.2 EV in additional dynamic range, and 1 stops in additional low light sensitivity. 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.		Pentax K-3	APS-C	24.1	6016	4000	1080/60i	23.7	13.4	1216	80
2.		Sony A7 II	Full Frame	24.0	6000	4000	1080/60p	24.9	13.6	2449	90
3.		Nikon D7100	APS-C	24.0	6000	4000	1080/60p	24.2	13.7	1256	83
4.		Pentax KP	APS-C	24.1	6016	4000	1080/60i	23.9	13.2	1699	81
5.		Pentax K-70	APS-C	24.0	6000	4000	1080/60i	23.8	13.1	1639	80
6.		Pentax K-S2	APS-C	20.0	5472	3648	1080/30p	23.6	12.9	1514	79
7.		Pentax K-3 II	APS-C	24.1	6016	4000	1080/60i	23.6	13.6	1106	80
8.		Pentax K-S1	APS-C	20.0	5472	3648	1080/30p	23.5	13.0	1061	78
9.		Pentax K-50	APS-C	16.1	4928	3264	1080/30p	23.7	13.0	1120	79
10.		Pentax K-5 II	APS-C	16.1	4928	3264	1080/25p	23.8	14.1	1235	82
11.		Pentax K-5	APS-C	16.1	4928	3264	1080/25p	23.7	14.1	1162	82
12.		Sony A7C	Full Frame	24.0	6000	4000	4K/30p	25.0	14.7	3407	95
13.		Sony A9 II	Full Frame	24.0	6000	4000	4K/30p	25.0	14.0	3434	93
14.		Sony A7 III	Full Frame	24.0	6000	4000	4K/30p	25.0	14.7	3730	96
15.		Sony A7	Full Frame	24.0	6000	4000	1080/60p	24.8	14.2	2248	90
16.		Sony A7R	Full Frame	36.2	7360	4912	1080/60p	25.6	14.1	2746	95
17.		Sony A77	APS-C	24.0	6000	4000	1080/60p	24.0	13.2	801	78
Note: DXO values in italics represent estimates based on sensor size and age.

Many modern cameras are not only capable of taking still images, but can also record movies. Both cameras under consideration are equipped with sensors that have a sufficiently high read-out speed for moving images, but the A7 II provides a faster frame rate than the K-3. It can shoot movie 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. For example, the A7 II has an electronic viewfinder (2400k dots), while the K-3 has an optical one. Both systems have their advantages, with the electronic viewfinder making it possible to project supplementary shooting information into the framing view, whereas the optical viewfinder offers lag-free viewing and a very clear framing image. The viewfinders of both cameras offer the same field of view (100%), but the viewfinder of the A7 II has a higher magnification than the one of the K-3 (0.71x 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 K-3, the Sony A7 II, 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 K-3	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	Y	Y
2.		Sony A7 II	2400	n	3.0 / 1230	tilting	n	1/8000s	5.0/s	n	Y
3.		Nikon D7100	optical	Y	3.2 / 1229	fixed	n	1/8000s	6.0/s	Y	n
4.		Pentax KP	optical	n	3.0 / 921	tilting	n	1/6000s	7.0/s	Y	Y
5.		Pentax K-70	optical	n	3.0 / 921	swivel	n	1/6000s	6.0/s	Y	Y
6.		Pentax K-S2	optical	n	3.0 / 921	swivel	n	1/6000s	5.4/s	Y	Y
7.		Pentax K-3 II	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	n	Y
8.		Pentax K-S1	optical	n	3.0 / 921	fixed	n	1/6000s	5.4/s	Y	Y
9.		Pentax K-50	optical	n	3.0 / 921	fixed	n	1/6000s	6.0/s	Y	Y
10.		Pentax K-5 II	optical	Y	3.0 / 921	fixed	n	1/8000s	7.0/s	Y	Y
11.		Pentax K-5	optical	Y	3.0 / 921	fixed	n	1/8000s	7.0/s	Y	Y
12.		Sony A7C	2360	n	3.0 / 922	swivel	Y	1/4000s	10.0/s	n	Y
13.		Sony A9 II	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
14.		Sony A7 III	2359	n	3.0 / 922	tilting	Y	1/8000s	10.0/s	n	Y
15.		Sony A7	2400	n	3.0 / 1230	tilting	n	1/8000s	5.0/s	n	n
16.		Sony A7R	2400	n	3.0 / 1230	tilting	n	1/8000s	4.0/s	n	n
17.		Sony A77	2359	Y	3.0 / 921	full-flex	n	1/8000s	12.0/s	Y	Y
Notes: *) 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 K-3 has one, while the A7 II does not. While the built-in flash of the K-3 is not very powerful, it can at times be useful as a fill-in light.

The Pentax K-3 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 K-3 writes its imaging data to SDXC cards, while the A7 II uses SDXC or Memory Stick PRO Duo cards. The K-3 features dual card slots, which can be very useful in case a memory card fails. In contrast, the A7 II only has one slot. 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 Pentax K-3 and Sony Alpha A7 II 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 K-3	Y	mono / mono	Y	Y	mini	3.0	-	-	-
2.		Sony A7 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
3.		Nikon D7100	Y	stereo / mono	Y	Y	mini	2.0	-	-	-
4.		Pentax KP	Y	stereo / mono	Y	-	-	2.0	Y	-	-
5.		Pentax K-70	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
6.		Pentax K-S2	Y	mono / mono	Y	-	micro	2.0	Y	Y	-
7.		Pentax K-3 II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
8.		Pentax K-S1	Y	stereo / mono	-	-	micro	2.0	-	-	-
9.		Pentax K-50	Y	mono / mono	-	-	micro	2.0	-	-	-
10.		Pentax K-5 II	Y	stereo / mono	Y	-	mini	2.0	-	-	-
11.		Pentax K-5	Y	stereo / mono	Y	-	mini	2.0	-	-	-
12.		Sony A7C	Y	stereo / mono	Y	Y	micro	3.2	Y	Y	Y
13.		Sony A9 II	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
14.		Sony A7 III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
15.		Sony A7	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
16.		Sony A7R	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
17.		Sony A77	Y	stereo / mono	Y	-	mini	2.0	-	-	-

It is notable that the A7 II offers wifi support, which can be a very convenient means to transfer image data to an off-camera location. In contrast, the K-3 does not provide wifi capability.

Studio photographers will appreciate that the Pentax K-3 (unlike the A7 II) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the K-3 and the A7 II have been discontinued, but can regularly be found used on ebay. The K-3 was replaced by the Pentax K-3 II, while the A7 II was followed by the Sony A7 III. Further information on the features and operation of the K-3 and A7 II can be found, respectively, in the Pentax K-3 Manual (free pdf) or the online Sony A7 II Manual.

Review summary

So how do things add up? Is the Pentax K-3 better than the Sony A7 II or vice versa? Below is a summary of the relative strengths of each of the two contestants.

Arguments in favor of the Pentax K-3:

• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• Brighter framing: Features an optical viewfinder for clear, lag-free composition.
• Easier setting verification: Features an LCD display on top to control shooting parameters.
• Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
• Faster burst: Shoots at higher frequency (8.3 vs 5 flaps/sec) to capture the decisive moment.
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• Longer lasting: Can take more shots (560 versus 350) on a single battery charge.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• 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.
• More affordable: Was introduced into a lower priced category (35 percent cheaper at launch).
• More heavily discounted: Has been on the market for longer (launched in October 2013).

Reasons to prefer the Sony Alpha A7 II:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Better image quality: Scores markedly higher (10 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (1.2 bits more color depth).
• Better low-light sensitivity: Can shoot in dim conditions (1 stops ISO advantage).
• Better video: Provides higher movie framerates (1080/60p versus 1080/60i).
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• More framing info: Has an electronic viewfinder that displays shooting data.
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.71x vs 0.63x).
• More detailed LCD: Has a higher resolution rear screen (1230k vs 1037k dots).
• More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
• Less heavy: Has a lower weight (by 201g or 25 percent) and is thus easier to take along.
• Easier travel charging: Can be conveniently charged via its USB port.
• More legacy lens friendly: Can use many non-native lenses via adapters.
• Easier file upload: Has wifi built in for automatic backup or image transfer to the web.
• Easier device pairing: Supports NFC for fast wireless image transfer over short distances.
• 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 A7 II emerges as the winner of the match-up (16 : 13 points). However, the relative importance of the various individual camera aspects will vary according to personal preferences and needs, so that you might like to apply corresponding weights to the particular features before making a decision 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 Pentax K-3 and the Sony A7 II place the cameras among the top in their class? Find out in the latest Best DSLR Camera and Best Mirrorless Interchangeable Lens Camera listings 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 K-3 and the A7 II 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 hands-on reviews by experts 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.		Pentax K-3	4/5	..	..	83/100	5/5	5/5	Oct 2013	1,299	ebay.com
2.		Sony A7 II	5/5	+	4/5	82/100	4.5/5	5/5	Nov 2014	1,999	ebay.com
3.		Nikon D7100	5/5	+ +	..	85/100	4.5/5	4.5/5	Feb 2013	1,199	ebay.com
4.		Pentax KP	4/5	..	3/5	82/100	5/5	4.5/5	Jan 2017	1,099	ebay.com
5.		Pentax K-70	4.5/5	..	4/5	79/100	4.5/5	4.5/5	Jun 2016	649	amazon.com
6.		Pentax K-S2	4.5/5	..	..	..	5/5	4.5/5	Feb 2015	749	ebay.com
7.		Pentax K-3 II	4.5/5	..	..	..	5/5	5/5	Apr 2015	1,099	ebay.com
8.		Pentax K-S1	4/5	..	..	..	4.5/5	4/5	Aug 2014	749	ebay.com
9.		Pentax K-50	5/5	..	..	..	5/5	4.5/5	Jun 2013	599	ebay.com
10.		Pentax K-5 II	5/5	..	..	80/100	5/5	4.5/5	Sep 2012	1,099	ebay.com
11.		Pentax K-5	4/5	..	..	83/100	5/5	4.5/5	Sep 2010	1,099	ebay.com
12.		Sony A7C	3.5/5	..	3.5/5	86/100	4/5	4/5	Sep 2020	1,799	amazon.com
13.		Sony A9 II	..	..	5/5	90/100	5/5	5/5	Oct 2019	4,499	amazon.com
14.		Sony A7 III	..	+ +	4.5/5	89/100	5/5	5/5	Feb 2018	1,999	amazon.com
15.		Sony A7	5/5	+ +	..	80/100	5/5	5/5	Oct 2013	1,699	ebay.com
16.		Sony A7R	5/5	+ +	..	82/100	4.5/5	5/5	Oct 2013	2,299	ebay.com
17.		Sony A77	5/5	91/100	..	81/100	..	5/5	Aug 2011	1,399	ebay.com
Notes: (+ +) 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. 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. 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? In case you would like to check on the differences and similarities of other camera models, just make your choice using the following search menu. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored.

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