Olympus E-520 vs Pentax 645D

The Olympus E-520 and the Pentax 645D are two digital cameras that were revealed to the public, respectively, in May 2008 and March 2010. Both are DSLR (Digital Single Lens Reflex) cameras that are based on a Four Thirds (E-520) and a medium format (645D) sensor. The Olympus has a resolution of 10 megapixels, whereas the Pentax provides 39.5 MP.

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

Headline Specifications

Olympus E-520		Pentax 645D
Digital single lens reflex		Digital single lens reflex
Four Thirds lenses		Pentax 645 mount lenses
10 MP – Four Thirds sensor		39.5 MP – Medium Format sensor
no Video		no Video
ISO 100-1,600		ISO 100-1,600
Optical viewfinder		Optical viewfinder
2.7" LCD – 215k dots		3.0" LCD – 921k dots
Fixed screen (not touch-sensitive)		Fixed screen (not touch-sensitive)
3.5 shutter flaps per second		1.1 shutter flaps per second
In-body stabilization		Lens stabilization only
not weather sealed		Weathersealed body
750 shots per battery charge		800 shots per battery charge
136 x 92 x 68 mm, 535 g		156 x 117 x 119 mm, 1480 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Olympus E-520 and the Pentax 645D? 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 Olympus E-520 and the Pentax 645D. The two cameras are presented according to their relative size. Three successive views from the front, the top, and the rear are shown. All size 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 645D is considerably larger (46 percent) than the Olympus E-520. Moreover, the 645D is substantially heavier (177 percent) than the E-520. It is noteworthy in this context that the 645D is splash and dust-proof, while the E-520 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 E-520 gets 750 shots out of its Olympus BLM-1 battery, while the 645D can take 800 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.		Olympus E-520	136 mm	92 mm	68 mm	535 g	750	n	May 2008	699	ebay.com
2.		Pentax 645D	156 mm	117 mm	119 mm	1480 g	800	Y	Mar 2010	9,995	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.		Leica S Typ 006	160 mm	120 mm	80 mm	1260 g	..	Y	Sep 2012	21,950	ebay.com
6.		Nikon D3S	160 mm	157 mm	88 mm	1240 g	4200	Y	Oct 2009	5,199	ebay.com
7.		Olympus E-30	142 mm	108 mm	75 mm	701 g	750	n	Nov 2008	1,299	ebay.com
8.		Olympus E-410	130 mm	91 mm	53 mm	435 g	500	n	Mar 2007	699	ebay.com
9.		Olympus E-420	130 mm	91 mm	53 mm	440 g	500	n	Mar 2008	599	ebay.com
10.		Olympus E-450	130 mm	91 mm	53 mm	440 g	500	n	Mar 2009	499	ebay.com
11.		Olympus E-510	136 mm	92 mm	68 mm	538 g	750	n	Mar 2007	799	ebay.com
12.		Olympus E-600	130 mm	94 mm	60 mm	535 g	500	n	Aug 2009	449	ebay.com
13.		Olympus E-620	130 mm	94 mm	60 mm	521 g	500	n	Feb 2009	699	ebay.com
14.		Olympus E-P1	121 mm	70 mm	36 mm	355 g	300	n	Jun 2009	799	ebay.com
15.		Olympus E-P2	121 mm	70 mm	36 mm	355 g	300	n	Nov 2009	799	ebay.com
16.		Panasonic L10	135 mm	96 mm	78 mm	556 g	450	n	Aug 2007	599	ebay.com
17.		Pentax 645Z	156 mm	117 mm	123 mm	1550 g	650	Y	Apr 2014	8,499	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 manufacturer’s suggested retail prices give an idea on the placement of the camera in the maker’s lineup and the broader market. The E-520 was launched at a markedly lower price (by 93 percent) than the 645D, 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 sensor inside a digital camera is one of the key determinants 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 are more costly to manufacture and tend to lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Olympus E-520 features a Four Thirds sensor and the Pentax 645D a medium format sensor. The sensor area in the 645D is 545 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 2.0 and 0.79. Both cameras feature a native aspect ratio (sensor width to sensor height) of 4:3.

With 39.5MP, the 645D offers a higher resolution than the E-520 (10MP), but the 645D nevertheless has larger individual pixels (pixel pitch of 6.06μm versus 4.74μm for the E-520) due to its larger sensor. Moreover, the 645D is a somewhat more recent model (by 1 year and 9 months) than the E-520, 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 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 Olympus E-520 are 18.2 x 13.7 inches or 46.3 x 34.7 cm for good quality, 14.6 x 10.9 inches or 37.1 x 27.8 cm for very good quality, and 12.2 x 9.1 inches or 30.9 x 23.2 cm for excellent quality prints.

The Olympus E-520 has a native sensitivity range from ISO 100 to ISO 1600. The Pentax 645D offers exactly the same ISO settings.

In terms of underlying technology, the E-520 is build around a CMOS sensor, while the 645D uses a CCD 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.

Since 2007, DXO Mark has published sensor performance measurements that have been derived using a consistent methodology. 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"). Of the two cameras under consideration, the 645D offers substantially better image quality than the E-520 (overall score 27 points higher). The advantage is based on 3.2 bits higher color depth, 2.2 EV in additional dynamic range, and 1.2 stops in additional low light sensitivity. The table below summarizes the physical sensor characteristics and sensor quality findings and compares them across a set of similar cameras.

Sensor Characteristics

		Camera Model	Sensor Class	Resolution (MP)	Horiz. Pixels	Vert. Pixels	Video Format	DXO Portrait	DXO Landscape	DXO Sports	DXO Overall
1.		Olympus E-520	Four Thirds	10.0	3648	2736	none	21.4	10.4	548	55
2.		Pentax 645D	Medium Format	39.5	7264	5440	none	24.6	12.6	1262	82
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.		Leica S Typ 006	Medium Format	37.5	7500	5000	none	23.9	12.2	824	76
6.		Nikon D3S	Full Frame	12.1	4256	2832	720/24p	23.5	12.0	3253	82
7.		Olympus E-30	Four Thirds	12.2	4032	3024	none	21.3	10.4	530	55
8.		Olympus E-410	Four Thirds	10.0	3648	2736	none	21.1	10.0	494	51
9.		Olympus E-420	Four Thirds	10.0	3648	2736	none	21.5	10.4	527	56
10.		Olympus E-450	Four Thirds	10.0	3648	2736	none	21.5	10.5	512	56
11.		Olympus E-510	Four Thirds	10.0	3648	2736	none	21.2	10.0	442	52
12.		Olympus E-600	Four Thirds	12.2	4032	3024	none	21.5	10.3	541	55
13.		Olympus E-620	Four Thirds	12.2	4032	3024	none	21.3	10.3	536	55
14.		Olympus E-P1	Four Thirds	12.2	4032	3024	720/30p	21.4	10.4	536	55
15.		Olympus E-P2	Four Thirds	12.2	4032	3024	720/30p	21.5	10.4	505	56
16.		Panasonic L10	Four Thirds	10.0	3648	2736	none	21.3	10.8	429	55
17.		Pentax 645Z	Medium Format	51.1	8256	6192	1080/60i	26.0	14.7	4505	101

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. The E-520 and the 645D 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 645D offers a wider field of view (98%) than the one in the E-520 (95%), so that a larger proportion of the captured image is visible in the finder. In addition, the viewfinder of the 645D has a higher magnification (0.78x vs 0.46x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The adjacent table lists some of the other core features of the Olympus E-520 and Pentax 645D 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.		Olympus E-520	optical	n	2.7 / 215	fixed	n	1/4000s	3.5/s	Y	Y
2.		Pentax 645D	optical	Y	3.0 / 921	fixed	n	1/4000s	1.1/s	n	n
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.		Leica S Typ 006	optical	Y	3.0 / 922	fixed	n	1/4000s	1.5/s	n	n
6.		Nikon D3S	optical	Y	3.0 / 921	fixed	n	1/8000s	11.0/s	n	n
7.		Olympus E-30	optical	Y	2.7 / 230	swivel	n	1/8000s	5.0/s	Y	Y
8.		Olympus E-410	optical	n	2.5 / 215	fixed	n	1/4000s	3.0/s	Y	n
9.		Olympus E-420	optical	n	2.7 / 215	fixed	n	1/4000s	3.5/s	Y	n
10.		Olympus E-450	optical	n	2.7 / 215	fixed	n	1/4000s	3.5/s	Y	n
11.		Olympus E-510	optical	n	2.5 / 215	fixed	n	1/4000s	3.0/s	Y	Y
12.		Olympus E-600	optical	n	2.7 / 230	swivel	n	1/4000s	4.0/s	Y	Y
13.		Olympus E-620	optical	n	2.7 / 230	swivel	n	1/4000s	4.0/s	Y	Y
14.		Olympus E-P1	none	n	3.0 / 230	fixed	n	1/4000s	3.0/s	n	Y
15.		Olympus E-P2	optional	n	3.0 / 230	fixed	n	1/4000s	3.0/s	n	Y
16.		Panasonic L10	optical	n	2.5 / 207	swivel	n	1/4000s	3.0/s	Y	n
17.		Pentax 645Z	optical	Y	3.2 / 1037	tilting	n	1/4000s	3.0/s	n	n
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 E-520 has one, while the 645D does not. While the built-in flash of the E-520 is not very powerful, it can at times be useful as a fill-in light.

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 E-520 writes its imaging data to Compact Flash or xD Picture cards, while the 645D uses SDXC cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails.

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 Olympus E-520 and Pentax 645D 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.		Olympus E-520	Y	- / -	-	-	-	2.0	-	-	-
2.		Pentax 645D	Y	stereo / -	-	-	-	2.0	-	-	-
3.		Canon 1D Mark IV	Y	stereo / -	Y	-	mini	2.0	-	-	-
4.		Canon 1D X	Y	mono / -	Y	-	mini	2.0	-	-	-
5.		Leica S Typ 006	Y	- / -	-	-	mini	2.0	-	-	-
6.		Nikon D3S	Y	stereo / -	-	-	mini	2.0	-	-	-
7.		Olympus E-30	Y	- / -	-	-	-	2.0	-	-	-
8.		Olympus E-410	Y	- / -	-	-	-	2.0	-	-	-
9.		Olympus E-420	Y	- / -	-	-	-	2.0	-	-	-
10.		Olympus E-450	Y	- / -	-	-	-	2.0	-	-	-
11.		Olympus E-510	Y	- / -	-	-	-	2.0	-	-	-
12.		Olympus E-600	Y	- / -	-	-	-	2.0	-	-	-
13.		Olympus E-620	Y	- / -	-	-	-	2.0	-	-	-
14.		Olympus E-P1	Y	stereo / -	-	-	mini	2.0	-	-	-
15.		Olympus E-P2	Y	stereo / -	-	-	mini	2.0	-	-	-
16.		Panasonic L10	Y	- / -	-	-	-	2.0	-	-	-
17.		Pentax 645Z	Y	stereo / mono	Y	-	mini	3.0	-	-	-

Studio photographers will appreciate that the Pentax 645D (unlike the E-520) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the E-520 and the 645D have been discontinued, but can regularly be found used on ebay. The 645D was replaced by the Pentax 645Z, while the E-520 does not have a direct successor. Further information on the features and operation of the E-520 and 645D can be found, respectively, in the Olympus E-520 Manual (free pdf) or the online Pentax 645D Manual.

Review summary

So what is the bottom line? Is the Olympus E-520 better than the Pentax 645D or vice versa? The listing below highlights the relative strengths of the two models.

Reasons to prefer the Olympus E-520:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Faster burst: Shoots at higher frequency (3.5 vs 1.1 flaps/sec) to capture the decisive moment.
• More compact: Is smaller (136x92mm vs 156x117mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 945g or 64 percent) and hence easier to carry around.
• Sharper images: Has hand-shake reducing image stabilization built-in.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• More affordable: Was introduced into a lower priced category (93 percent cheaper at launch).
• More heavily discounted: Has been on the market for longer (launched in May 2008).

Arguments in favor of the Pentax 645D:

• More detail: Has more megapixels (39.5 vs 10MP), which boosts linear resolution by 99%.
• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• Better image quality: Scores substantially higher (27 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (3.2 bits more color depth).
• More dynamic range: Captures a broader range of light and dark details (2.2 EV of extra DR).
• Better low-light sensitivity: Can shoot in dim conditions (1.2 stops ISO advantage).
• More complete view: Has a viewfinder with a larger field of view (98% vs 95%).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.78x vs 0.46x).
• Easier setting verification: Features a control panel on top to check shooting parameters.
• 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 215k dots).
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• Better sealing: Is splash and dust sealed for shooting in inclement weather conditions.
• Better studio light control: Has a PC Sync socket to connect to professional strobe lights.
• More modern: Was introduced somewhat (1 year and 9 months) more recently.

If the count of relative strengths (bullet points above) is taken as a measure, the 645D is the clear winner of the contest (15 : 8 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 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 Olympus E-520 and the Pentax 645D 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 E-520 and the 645D in practical situations. User reviews, such as those found at amazon, can sometimes inform about these issues, but such feedback is often incomplete, inconsistent, and biased.

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.		Olympus E-520	..	87/100	..	+ +	4.5/5	4.5/5	May 2008	699	ebay.com
2.		Pentax 645D	5/5	..	..	..	..	..	Mar 2010	9,995	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.		Leica S Typ 006	..	..	..	..	..	..	Sep 2012	21,950	ebay.com
6.		Nikon D3S	5/5	..	..	89/100	4.5/5	5/5	Oct 2009	5,199	ebay.com
7.		Olympus E-30	..	..	..	71/100	4.5/5	4/5	Nov 2008	1,299	ebay.com
8.		Olympus E-410	..	86/100	..	+ +	4/5	4.5/5	Mar 2007	699	ebay.com
9.		Olympus E-420	..	85/100	..	+ +	4/5	4.5/5	Mar 2008	599	ebay.com
10.		Olympus E-450	..	..	..	..	4/5	4/5	Mar 2009	499	ebay.com
11.		Olympus E-510	..	89/100	..	+ +	3.5/5	4.5/5	Mar 2007	799	ebay.com
12.		Olympus E-600	..	..	..	..	..	4.5/5	Aug 2009	449	ebay.com
13.		Olympus E-620	3/5	88/100	..	72/100	4.5/5	5/5	Feb 2009	699	ebay.com
14.		Olympus E-P1	..	+	..	66/100	4/5	4.5/5	Jun 2009	799	ebay.com
15.		Olympus E-P2	3/5	+	..	69/100	4/5	4.5/5	Nov 2009	799	ebay.com
16.		Panasonic L10	..	85/100	..	+	3.5/5	4/5	Aug 2007	599	ebay.com
17.		Pentax 645Z	5/5	..	3.5/5	..	4.5/5	5/5	Apr 2014	8,499	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. Thus, a score needs to be put into the context of the launch date and the launch price of the camera, and rating-comparisons among cameras that span long time periods or concern very differently equipped models make little sense. 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? If you would like to see a different side-by-side camera review, just use the search menu below. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored.

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