Pentax 645D vs Sony A68

The Pentax 645D and the Sony Alpha SLT-A68 are two digital cameras that were officially introduced, respectively, in March 2010 and November 2015. Both are DSLR (Digital Single Lens Reflex) cameras that are based on a medium format (645D) and an APS-C (A68) sensor. The Pentax has a resolution of 39.5 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 645D		Sony A68
Digital single lens reflex		Digital single lens reflex
Pentax 645 mount lenses		Sony A mount lenses
39.5 MP – Medium Format sensor		24 MP – APS-C sensor
no Video		1080/60i Video
ISO 100-1,600		ISO 100-25,600
Optical viewfinder		Electronic viewfinder (1440k dots)
3.0" LCD – 921k dots		2.7" LCD – 460k dots
Fixed screen (not touch-sensitive)		Tilting screen (no touchscreen)
1.1 shutter flaps per second		8 shutter flaps per second
Lens stabilization only		In-body stabilization
Weathersealed body		not weather sealed
800 shots per battery charge		540 shots per battery charge
156 x 117 x 119 mm, 1480 g		143 x 104 x 81 mm, 610 g

Check 645D offers at
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Check A68 offers at
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Going beyond this snapshot of core features and characteristics, what are the differences between the Pentax 645D and the Sony Alpha SLT-A68? 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 Pentax 645D and the Sony A68 are illustrated 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.

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Sony A68 is notably smaller (19 percent) than the Pentax 645D. Moreover, the A68 is substantially lighter (59 percent) than the 645D. It is worth mentioning in this context that the 645D is splash and dust resistant, while the A68 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 A68 can take 540 images on a single charge of its Sony NP-FM500H 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.		Sony A68	143 mm	104 mm	81 mm	610 g	540	n	Nov 2015	699	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.		Leica S Typ 006	160 mm	120 mm	80 mm	1260 g	..	Y	Sep 2012	21,950	ebay.com
7.		Nikon D3S	160 mm	157 mm	88 mm	1240 g	4200	Y	Oct 2009	5,199	ebay.com
8.		Nikon D5	160 mm	159 mm	92 mm	1415 g	3780	Y	Jan 2016	6,499	ebay.com
9.		Nikon D810	146 mm	123 mm	82 mm	980 g	1200	Y	Jun 2014	3,299	ebay.com
10.		Nikon D850	146 mm	124 mm	79 mm	1005 g	1840	Y	Jul 2017	3,299	amazon.com
11.		Pentax 645Z	156 mm	117 mm	123 mm	1550 g	650	Y	Apr 2014	8,499	ebay.com
12.		Pentax K-S1	121 mm	93 mm	70 mm	558 g	410	n	Aug 2014	749	ebay.com
13.		Sony A7R	127 mm	94 mm	48 mm	465 g	340	Y	Oct 2013	2,299	ebay.com
14.		Sony A58	129 mm	95 mm	78 mm	492 g	690	n	Feb 2013	599	ebay.com
15.		Sony A77	143 mm	104 mm	81 mm	732 g	470	Y	Aug 2011	1,399	ebay.com
16.		Sony A77 II	143 mm	104 mm	81 mm	647 g	480	Y	May 2014	1,199	ebay.com
17.		Sony A6000	120 mm	67 mm	45 mm	344 g	360	n	Feb 2014	599	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 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 A68 was launched at a markedly lower price (by 93 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 size of the imaging sensor is a crucial determinant of image quality. A large sensor will generally have larger individual pixels that offer better low-light sensitivity, provide wider dynamic range, and have richer color-depth than smaller pixels in a sensor of the same technological generation. Further, a large sensor camera will give the photographer additional creative options when using shallow depth-of-field to isolate a subject from its 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 645D features a medium format sensor and the Sony A68 an APS-C sensor. The sensor area in the A68 is 75 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 A68 offers a 3:2 aspect.

With 39.5MP, the 645D offers a higher resolution than the A68 (24MP), but the 645D nevertheless has larger individual pixels (pixel pitch of 6.06μm versus 3.91μm for the A68) due to its larger sensor. However, the A68 is a much more recent model (by 5 years and 7 months) than the 645D, 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 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 Sony A68 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 Pentax 645D has a native sensitivity range from ISO 100 to ISO 1600. The corresponding ISO settings for the Sony Alpha SLT-A68 are ISO 100 to ISO 25600 (no boost).

In terms of underlying technology, the 645D is build around a CCD sensor, while the A68 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 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 Overall DXO ratings for the two cameras under consideration are close, suggesting that they provide similar imaging performance. 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.		Pentax 645D	Medium Format	39.5	7264	5440	none	24.6	12.6	1262	82
2.		Sony A68	APS-C	24.0	6000	4000	1080/60i	24.1	13.5	701	79
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.		Leica S Typ 006	Medium Format	37.5	7500	5000	none	23.9	12.2	824	76
7.		Nikon D3S	Full Frame	12.1	4256	2832	720/24p	23.5	12.0	3253	82
8.		Nikon D5	Full Frame	20.7	5588	3712	4K/30p	25.1	12.3	2343	88
9.		Nikon D810	Full Frame	36.2	7360	4912	1080/60p	25.7	14.8	2853	97
10.		Nikon D850	Full Frame	45.4	8256	5504	4K/30p	26.4	14.8	2660	100
11.		Pentax 645Z	Medium Format	51.1	8256	6192	1080/60i	26.0	14.7	4505	101
12.		Pentax K-S1	APS-C	20.0	5472	3648	1080/30p	23.5	13.0	1061	78
13.		Sony A7R	Full Frame	36.2	7360	4912	1080/60p	25.6	14.1	2746	95
14.		Sony A58	APS-C	19.8	5456	3632	1080/60i	23.3	12.5	753	74
15.		Sony A77	APS-C	24.0	6000	4000	1080/60p	24.0	13.2	801	78
16.		Sony A77 II	APS-C	24.0	6000	4000	1080/60p	24.4	13.4	1013	82
17.		Sony A6000	APS-C	24.0	6000	4000	1080/60p	24.1	13.1	1347	82

Many modern cameras cannot only take still pictures, but also record videos. The A68 indeed provides for movie recording, while the 645D does not. The highest resolution format that the A68 can use is 1080/60i.

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. For example, the A68 has an electronic viewfinder (1440k dots), while the 645D 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 viewfinder in the A68 offers a wider field of view (100%) than the one in the 645D (98%), so that a larger proportion of the captured image is visible in the finder. On the other hand, the viewfinder of the 645D has a higher magnification (0.78x vs 0.57x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The table below summarizes some of the other core capabilities of the Pentax 645D and Sony A68 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 645D	optical	Y	3.0 / 921	fixed	n	1/4000s	1.1/s	n	n
2.		Sony A68	1440	Y	2.7 / 460	tilting	n	1/4000s	8.0/s	Y	Y
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.		Leica S Typ 006	optical	Y	3.0 / 922	fixed	n	1/4000s	1.5/s	n	n
7.		Nikon D3S	optical	Y	3.0 / 921	fixed	n	1/8000s	11.0/s	n	n
8.		Nikon D5	optical	Y	3.2 / 2359	fixed	Y	1/8000s	14.0/s	n	n
9.		Nikon D810	optical	Y	3.2 / 1229	fixed	n	1/8000s	5.0/s	Y	n
10.		Nikon D850	optical	Y	3.2 / 2359	tilting	Y	1/8000s	9.0/s	n	n
11.		Pentax 645Z	optical	Y	3.2 / 1037	tilting	n	1/4000s	3.0/s	n	n
12.		Pentax K-S1	optical	n	3.0 / 921	fixed	n	1/6000s	5.4/s	Y	Y
13.		Sony A7R	2400	n	3.0 / 1230	tilting	n	1/8000s	4.0/s	n	n
14.		Sony A58	1440	n	2.7 / 460	tilting	n	1/4000s	5.0/s	Y	Y
15.		Sony A77	2359	Y	3.0 / 921	full-flex	n	1/8000s	12.0/s	Y	Y
16.		Sony A77 II	2359	Y	3.0 / 1229	full-flex	n	1/8000s	12.0/s	Y	Y
17.		Sony A6000	1440	n	3.0 / 922	tilting	n	1/4000s	11.0/s	Y	n
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that differentiates the A68 and the 645D is in-body image stabilization (IBIS). The A68 reduces the risk of handshake-induced blur with all attached lenses, while the 645D offers no blur reduction with lenses that themselves do not provide optical image stabilization.

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 A68 uses SDXC or Memory Stick PRO Duo cards. The 645D features dual card slots, which can be very useful in case a memory card fails. In contrast, the A68 only has one slot. The A68 supports UHS-I cards (Ultra High Speed data transfer of up to 104 MB/s), while the 645D cannot take advantage of Ultra High Speed SD 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 645D and Sony Alpha SLT-A68 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.		Sony A68	Y	stereo / mono	Y	-	micro	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.		Leica S Typ 006	Y	- / -	-	-	mini	2.0	-	-	-
7.		Nikon D3S	Y	stereo / -	-	-	mini	2.0	-	-	-
8.		Nikon D5	Y	stereo / mono	Y	Y	mini	3.0	-	-	-
9.		Nikon D810	Y	stereo / mono	Y	Y	mini	3.0	Y	-	-
10.		Nikon D850	Y	stereo / mono	Y	Y	mini	3.0	Y	Y	Y
11.		Pentax 645Z	Y	stereo / mono	Y	-	mini	3.0	-	-	-
12.		Pentax K-S1	Y	stereo / mono	-	-	micro	2.0	-	-	-
13.		Sony A7R	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
14.		Sony A58	Y	stereo / mono	Y	-	mini	2.0	-	-	-
15.		Sony A77	Y	stereo / mono	Y	-	mini	2.0	-	-	-
16.		Sony A77 II	Y	stereo / mono	Y	-	mini	2.0	Y	Y	-
17.		Sony A6000	Y	stereo / mono	-	-	micro	2.0	Y	Y	-

Studio photographers will appreciate that the Pentax 645D (unlike the A68) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the 645D and the A68 have been discontinued, but can regularly be found used on ebay. The 645D was replaced by the Pentax 645Z, while the A68 does not have a direct successor. Further information on the features and operation of the 645D and A68 can be found, respectively, in the Pentax 645D Manual (free pdf) or the online Sony A68 Manual.

Review summary

So what is the bottom line? Is there a clear favorite between the Pentax 645D and the Sony A68? Which camera is better? A synthesis of the relative strong points of each of the models is listed below.

Advantages of the Pentax 645D:

• More detail: Offers more megapixels (39.5 vs 24MP) with a 26% higher linear resolution.
• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• Better low-light sensitivity: Requires less light for good images (0.8 stops ISO advantage).
• Brighter framing: Features an optical viewfinder for clear, lag-free composition.
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.78x vs 0.57x).
• Larger screen: Has a bigger rear LCD (3.0" vs 2.7") for image review and settings control.
• More detailed LCD: Has a higher resolution rear screen (921k vs 460k dots).
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• Longer lasting: Can take more shots (800 versus 540) on a single battery charge.
• 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 heavily discounted: Has been available for much longer (launched in March 2010).

Reasons to prefer the Sony Alpha SLT-A68:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• More dynamic range: Captures a broader range of light and dark details (0.9 EV of extra DR).
• Broader imaging potential: Can capture not only stills but also 1080/60i video.
• More framing info: Has an electronic viewfinder that displays shooting data.
• More complete view: Has a viewfinder with a larger field of view (100% vs 98%).
• More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
• Faster burst: Shoots at higher frequency (8 vs 1.1 flaps/sec) to capture the decisive moment.
• More compact: Is smaller (143x104mm vs 156x117mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 870g or 59 percent) and is thus easier to take along.
• Sharper images: Has stabilization technology built-in to reduce the impact of hand-shake.
• Easier fill-in: Has a small integrated flash to brighten shadows of backlit subjects.
• Faster buffer clearing: Has an SD card interface that supports the UHS-I standard.
• More affordable: Was introduced into a lower priced category (93 percent cheaper at launch).
• More modern: Reflects 5 years and 7 months of technical progress since the 645D launch.

If the number of relative strengths (bullet points above) is taken as a guide, the A68 comes out slightly ahead of the 645D (14 : 13 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 Pentax 645D and the Sony A68 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 incomplete and does no justice, for example, to the way the 645D or the A68 perform in practice. 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 645D	5/5	..	..	..	..	..	Mar 2010	9,995	ebay.com
2.		Sony A68	3/5	..	..	..	4/5	4/5	Nov 2015	699	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.		Leica S Typ 006	..	..	..	..	..	..	Sep 2012	21,950	ebay.com
7.		Nikon D3S	5/5	..	..	89/100	4.5/5	5/5	Oct 2009	5,199	ebay.com
8.		Nikon D5	..	..	4/5	89/100	4.5/5	5/5	Jan 2016	6,499	ebay.com
9.		Nikon D810	5/5	..	5/5	86/100	5/5	4.5/5	Jun 2014	3,299	ebay.com
10.		Nikon D850	4.5/5	+ +	5/5	89/100	4.5/5	5/5	Jul 2017	3,299	amazon.com
11.		Pentax 645Z	5/5	..	3.5/5	..	4.5/5	5/5	Apr 2014	8,499	ebay.com
12.		Pentax K-S1	4/5	..	..	..	4.5/5	4/5	Aug 2014	749	ebay.com
13.		Sony A7R	5/5	+ +	..	82/100	4.5/5	5/5	Oct 2013	2,299	ebay.com
14.		Sony A58	3/5	..	..	..	4.5/5	4.5/5	Feb 2013	599	ebay.com
15.		Sony A77	5/5	91/100	..	81/100	..	5/5	Aug 2011	1,399	ebay.com
16.		Sony A77 II	4/5	..	..	80/100	4.5/5	5/5	May 2014	1,199	ebay.com
17.		Sony A6000	5/5	+	4.5/5	80/100	4.5/5	5/5	Feb 2014	599	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. 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

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.

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