Pentax K-3 III vs Sony A6600

The Pentax K-3 III and the Sony Alpha A6600 are two enthusiast cameras that were revealed to the public, respectively, in March 2021 and August 2019. The K-3 III is a DSLR, while the A6600 is a mirrorless interchangeable lens camera. Both cameras are equipped with an APS-C sensor. The Pentax has a resolution of 25.6 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 III		Sony A6600
Digital single lens reflex		Mirrorless system camera
Pentax K mount lenses		Sony E mount lenses
25.6 MP – APS-C sensor		24 MP – APS-C sensor
4K/30p Video		4K/30p Video
ISO 100-160,000		ISO 100-32,000 (100 - 102,400)
Optical viewfinder		Electronic viewfinder (2359k dots)
3.2" LCD – 1620k dots		3.0" LCD – 922k dots
Fixed touchscreen		Tilting touchscreen
12 shutter flaps per second		11 shutter flaps per second
In-body stabilization		In-body stabilization
Weathersealed body		Weathersealed body
800 shots per battery charge		810 shots per battery charge
135 x 104 x 74 mm, 820 g		120 x 67 x 69 mm, 503 g

Check K-3 III price at
amazon.com
Check A6600 price at
amazon.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Pentax K-3 III and the Sony Alpha A6600? 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 K-3 III and the Sony A6600. 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 A6600 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 A6600 is considerably smaller (43 percent) than the Pentax K-3 III. Moreover, the A6600 is substantially lighter (39 percent) than the K-3 III. 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 III gets 800 shots out of its Pentax D-LI90 battery, while the A6600 can take 810 images on a single charge of its Sony NP-FZ100 power pack. The power pack in the A6600 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 III	135 mm	104 mm	74 mm	820 g	800	Y	Mar 2021	1,999	amazon.com
2.		Sony A6600	120 mm	67 mm	69 mm	503 g	810	Y	Aug 2019	1,399	amazon.com
3.		Fujifilm X-T4	135 mm	93 mm	64 mm	607 g	500	Y	Feb 2020	1,699	ebay.com
4.		Fujifilm X-H1	140 mm	97 mm	86 mm	673 g	310	Y	Feb 2018	1,899	ebay.com
5.		Nikon Z6 II	134 mm	101 mm	70 mm	705 g	410	Y	Oct 2020	1,999	amazon.com
6.		Panasonic S5	133 mm	98 mm	82 mm	714 g	440	Y	Sep 2020	1,999	amazon.com
7.		Pentax KP	132 mm	101 mm	76 mm	703 g	390	Y	Jan 2017	1,099	ebay.com
8.		Pentax K-70	126 mm	93 mm	74 mm	688 g	410	Y	Jun 2016	649	ebay.com
9.		Pentax K-S2	123 mm	91 mm	73 mm	678 g	410	Y	Feb 2015	749	ebay.com
10.		Pentax K-3 II	131 mm	100 mm	77 mm	800 g	720	Y	Apr 2015	1,099	ebay.com
11.		Pentax K-3	131 mm	100 mm	77 mm	800 g	560	Y	Oct 2013	1,299	ebay.com
12.		Pentax K-5 II	131 mm	97 mm	73 mm	760 g	740	Y	Sep 2012	1,099	ebay.com
13.		Sony A6700	122 mm	69 mm	64 mm	493 g	570	Y	Jul 2023	1,399	amazon.com
14.		Sony A7C	124 mm	71 mm	60 mm	509 g	740	Y	Sep 2020	1,799	amazon.com
15.		Sony A6500	120 mm	67 mm	53 mm	453 g	350	Y	Oct 2016	1,399	ebay.com
16.		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 manufacturer’s suggested retail prices give an idea on the placement of the camera in the maker’s lineup and the broader market. The A6600 was launched at a markedly lower price (by 30 percent) than the K-3 III, 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. Then, after the new model is out, very good deals can frequently be found on the pre-owned market.

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. 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.

Both cameras under consideration feature an APS-C sensor, but their sensors differ slightly in size. The sensor area in the A6600 is 2 percent bigger. They nevertheless have the same format factor of 1.5. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

Despite having a slightly smaller sensor, the Pentax K-3 III offers a higher resolution of 25.6 megapixels, compared with 24 MP of the Sony A6600. 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 3.76μm versus 3.91μm for the A6600). However, it should be noted that the K-3 III is a somewhat more recent model (by 1 year and 7 months) than the A6600, and its sensor might have benefitted from technological advances during this time that partly offset its pixel-size disadvantage. Coming back to sensor resolution, it should be mentioned that the K-3 III has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

The A6600 has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

Unlike the A6600, 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 Pentax K-3 III has a native sensitivity range from ISO 100 to ISO 160000. The corresponding ISO settings for the Sony Alpha A6600 are ISO 100 to ISO 32000, with the possibility to increase the ISO range to 100-102400.

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 is based on lab testing and assigns an overall score to each camera sensor, as well as ratings for dynamic range ("DXO Landscape"), color depth ("DXO Portrait"), and low-light sensitivity ("DXO Sports"). 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 III	APS-C	25.6	6192	4128	4K/30p	24.2	13.7	2083	85
2.		Sony A6600	APS-C	24.0	6000	4000	4K/30p	23.8	13.4	1497	82
3.		Fujifilm X-T4	APS-C	26.0	6240	4160	4K/60p	24.1	13.6	1995	84
4.		Fujifilm X-H1	APS-C	24.0	6000	4000	4K/30p	24.0	13.3	1806	82
5.		Nikon Z6 II	Full Frame	24.3	6048	4024	4K/60p	25.0	14.4	3303	94
6.		Panasonic S5	Full Frame	24.0	6000	4000	4K/60p	25.1	14.5	2697	94
7.		Pentax KP	APS-C	24.1	6016	4000	1080/60i	23.9	13.2	1699	81
8.		Pentax K-70	APS-C	24.0	6000	4000	1080/60i	23.8	13.1	1639	80
9.		Pentax K-S2	APS-C	20.0	5472	3648	1080/30p	23.6	12.9	1514	79
10.		Pentax K-3 II	APS-C	24.1	6016	4000	1080/60i	23.6	13.6	1106	80
11.		Pentax K-3	APS-C	24.1	6016	4000	1080/60i	23.7	13.4	1216	80
12.		Pentax K-5 II	APS-C	16.1	4928	3264	1080/25p	23.8	14.1	1235	82
13.		Sony A6700	APS-C	25.6	6192	4128	4K/120p	24.3	14.0	2329	86
14.		Sony A7C	Full Frame	24.0	6000	4000	4K/30p	25.0	14.7	3407	95
15.		Sony A6500	APS-C	24.0	6000	4000	4K/30p	24.5	13.7	1405	85
16.		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. The two cameras under consideration both have sensors whose read-out speed is fast enough to capture moving pictures, and both provide the same movie specifications (4K/30p).

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. For example, the A6600 has an electronic viewfinder (2359k dots), while the K-3 III 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%), as well as the same magnification (0.70x). The table below summarizes some of the other core capabilities of the Pentax K-3 III and Sony A6600 in connection with corresponding information for a sample of similar 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 III	optical	Y	3.2 / 1620	fixed	Y	1/8000s	12.0/s	n	Y
2.		Sony A6600	2359	n	3.0 / 922	tilting	Y	1/4000s	11.0/s	n	Y
3.		Fujifilm X-T4	3690	n	3.0 / 1620	swivel	Y	1/8000s	15.0/s	n	Y
4.		Fujifilm X-H1	3690	Y	3.0 / 1040	full-flex	Y	1/8000s	14.0/s	n	Y
5.		Nikon Z6 II	3690	Y	3.2 / 2100	tilting	Y	1/8000s	14.0/s	n	Y
6.		Panasonic S5	2360	n	3.0 / 1840	swivel	Y	1/8000s	7.0/s	n	Y
7.		Pentax KP	optical	n	3.0 / 921	tilting	n	1/6000s	7.0/s	Y	Y
8.		Pentax K-70	optical	n	3.0 / 921	swivel	n	1/6000s	6.0/s	Y	Y
9.		Pentax K-S2	optical	n	3.0 / 921	swivel	n	1/6000s	5.4/s	Y	Y
10.		Pentax K-3 II	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	n	Y
11.		Pentax K-3	optical	Y	3.2 / 1037	fixed	n	1/8000s	8.3/s	Y	Y
12.		Pentax K-5 II	optical	Y	3.0 / 921	fixed	n	1/8000s	7.0/s	Y	Y
13.		Sony A6700	2360	n	3.0 / 1037	swivel	Y	1/4000s	11.0/s	n	Y
14.		Sony A7C	2360	n	3.0 / 922	swivel	Y	1/4000s	10.0/s	n	Y
15.		Sony A6500	2359	n	3.0 / 922	tilting	Y	1/4000s	11.0/s	Y	Y
16.		Sony A77	2359	Y	3.0 / 921	full-flex	n	1/8000s	12.0/s	Y	Y
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that is present on the K-3 III, but is missing on the A6600 is a top-level LCD. While being, of course, smaller than the rear screen, the control panel conveys some of the essential shooting information and can be convenient for quick and easy settings verification.

The reported shutter speed information refers to the use of the mechanical shutter. Yet, some cameras only have an electronic shutter, while others have an electronic shutter in addition to a mechanical one. In fact, the A6600 is one of those camera that have an additional electronic shutter, which makes completely silent shooting possible. However, this mode is less suitable for photographing moving objects (risk of rolling shutter) or shooting under artificial light sources (risk of flickering).

The Pentax K-3 III and the Sony A6600 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 K-3 III writes its imaging data to SDXC cards, while the A6600 uses SDXC or Memory Stick PRO Duo cards. The K-3 III features dual card slots, which can be very useful in case a memory card fails. In contrast, the A6600 only has one slot. The K-3 III supports UHS-II cards (on its first slot), while the A6600 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 Pentax K-3 III and Sony Alpha A6600 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 III	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
2.		Sony A6600	Y	stereo / mono	Y	Y	YES	2.0	Y	Y	Y
3.		Fujifilm X-T4	Y	stereo / mono	Y	-	micro	3.1	Y	-	Y
4.		Fujifilm X-H1	Y	stereo / mono	Y	-	micro	3.0	Y	-	-
5.		Nikon Z6 II	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
6.		Panasonic S5	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
7.		Pentax KP	Y	stereo / mono	Y	-	-	2.0	Y	-	-
8.		Pentax K-70	Y	stereo / mono	Y	-	mini	2.0	Y	-	-
9.		Pentax K-S2	Y	mono / mono	Y	-	micro	2.0	Y	Y	-
10.		Pentax K-3 II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
11.		Pentax K-3	Y	mono / mono	Y	Y	mini	3.0	-	-	-
12.		Pentax K-5 II	Y	stereo / mono	Y	-	mini	2.0	-	-	-
13.		Sony A6700	Y	stereo / mono	Y	Y	YES	3.2	Y	Y	Y
14.		Sony A7C	Y	stereo / mono	Y	Y	micro	3.2	Y	Y	Y
15.		Sony A6500	Y	stereo / mono	Y	-	micro	2.0	Y	Y	-
16.		Sony A77	Y	stereo / mono	Y	-	mini	2.0	-	-	-

Studio photographers will appreciate that the Pentax K-3 III (unlike the A6600) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

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.

Both the K-3 III and the A6600 are recent models that are part of the current product line-up. The A6600 replaced the earlier Sony A6500, while the K-3 III followed on from the Pentax K-3 II. Further information on the features and operation of the K-3 III and A6600 can be found, respectively, in the Pentax K-3 III Manual (free pdf) or the online Sony A6600 Manual.

Review summary

So what conclusions can be drawn? Which of the two cameras – the Pentax K-3 III or the Sony A6600 – 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.

Advantages of the Pentax K-3 III:

• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• High quality composites: Can combine several shots after pixel-shifting its sensor.
• 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.
• More detailed LCD: Has a higher resolution rear screen (1620k vs 922k dots).
• Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
• Easier geotagging: Features an internal GPS sensor to log localization data.
• Faster data transfer: Supports a more advanced USB protocol (3.2 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: Supports a more advanced SD data transfer standard (UHS-II vs UHS-I).
• More modern: Is somewhat more recent (announced 1 year and 7 months after the A6600).

Reasons to prefer the Sony Alpha A6600:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• More framing info: Has an electronic viewfinder that displays shooting data.
• More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
• More selfie-friendly: Has an articulated screen that can be turned to be front-facing.
• Less disturbing: Has an electronic shutter option for completely silent shooting.
• More compact: Is smaller (120x67mm vs 135x104mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 317g or 39 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 device pairing: Supports NFC for fast wireless image transfer over short distances.
• More affordable: Was introduced into a lower priced category (30 percent cheaper at launch).
• More heavily discounted: Has been on the market for longer (launched in August 2019).

If the count of relative strengths (bullet points above) is taken as a measure, the match-up finishes in a tie (13 points each). 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 wedding photographer will view the differences between cameras in a way that diverges from the perspective of a travel photog, and a person interested in cityscapes has distinct needs from a macro 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 III and the Sony A6600 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 specs-based evaluation of cameras can be instructive in revealing their potential as photographic tools, it says little about, for example, the shooting experience and imaging performance of the K-3 III and the A6600 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 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 III	4/5	..	3/5	..	4.5/5	..	Mar 2021	1,999	amazon.com
2.		Sony A6600	4/5	+	4/5	83/100	4.5/5	4/5	Aug 2019	1,399	amazon.com
3.		Fujifilm X-T4	5/5	+ +	5/5	88/100	5/5	5/5	Feb 2020	1,699	ebay.com
4.		Fujifilm X-H1	..	+	5/5	86/100	4.5/5	4.5/5	Feb 2018	1,899	ebay.com
5.		Nikon Z6 II	4.5/5	..	4/5	89/100	4.5/5	4.5/5	Oct 2020	1,999	amazon.com
6.		Panasonic S5	4.5/5	+ +	4.5/5	88/100	4.5/5	4.5/5	Sep 2020	1,999	amazon.com
7.		Pentax KP	4/5	..	3/5	82/100	5/5	4.5/5	Jan 2017	1,099	ebay.com
8.		Pentax K-70	4.5/5	..	4/5	79/100	4.5/5	4.5/5	Jun 2016	649	ebay.com
9.		Pentax K-S2	4.5/5	..	..	..	5/5	4.5/5	Feb 2015	749	ebay.com
10.		Pentax K-3 II	4.5/5	..	..	..	5/5	5/5	Apr 2015	1,099	ebay.com
11.		Pentax K-3	4/5	..	..	83/100	5/5	5/5	Oct 2013	1,299	ebay.com
12.		Pentax K-5 II	5/5	..	..	80/100	5/5	4.5/5	Sep 2012	1,099	ebay.com
13.		Sony A6700	4.5/5	+	4.5/5	88/100	4.5/5	4.5/5	Jul 2023	1,399	amazon.com
14.		Sony A7C	3.5/5	..	3.5/5	86/100	4/5	4/5	Sep 2020	1,799	amazon.com
15.		Sony A6500	5/5	+ +	3.5/5	85/100	4.5/5	4.5/5	Oct 2016	1,399	ebay.com
16.		Sony A77	5/5	91/100	..	81/100	..	5/5	Aug 2011	1,399	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The review scores listed above should be treated with care, though. The ratings are only valid when referring to cameras in the same category and of the same age. 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, please note that some of the review sites have changed their methodology and reporting over time.

Check K-3 III price at
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Check A6600 price at
amazon.com

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 use the search menu 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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