Canon 20D vs Olympus E-PM1

The Canon EOS 20D and the Olympus PEN E-PM1 are two digital cameras that were revealed to the public, respectively, in August 2004 and June 2011. The 20D is a DSLR, while the E-PM1 is a mirrorless interchangeable lens camera. The cameras are based on an APS-C (20D) and a Four Thirds (E-PM1) sensor. The Canon has a resolution of 8.2 megapixels, whereas the Olympus provides 12.2 MP.

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

Headline Specifications

Canon 20D		Olympus E-PM1
Digital single lens reflex		Mirrorless system camera
Canon EF mount lenses		Micro Four Thirds lenses
8.2 MP – APS-C sensor		12.2 MP – Four Thirds sensor
no Video		1080/60i Video
ISO 100-1,600 (100 - 3,200)		ISO 100-12,800
Optical viewfinder		Viewfinder optional
1.8" LCD – 118k dots		3.0" LCD – 460k dots
Fixed screen (not touch-sensitive)		Fixed screen (not touch-sensitive)
5 shutter flaps per second		5.5 shutter flaps per second
Lens stabilization only		In-body stabilization
700 shots per battery charge		330 shots per battery charge
144 x 106 x 72 mm, 770 g		110 x 64 x 34 mm, 265 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Canon EOS 20D and the Olympus PEN E-PM1? 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 Canon 20D and the Olympus E-PM1 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 width, height and depth dimensions are rounded to the nearest millimeter.

The E-PM1 can be obtained in six different colors (black, silver, brown, pink, purple, white), while the 20D 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 Olympus E-PM1 is considerably smaller (54 percent) than the Canon 20D. Moreover, the E-PM1 is substantially lighter (66 percent) than the 20D. In this context, it is worth noting that neither the 20D nor the E-PM1 are weather-sealed.

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. A larger imaging sensor will tend to go along with bigger and heavier lenses, although exceptions exist. You can compare the optics available for the two cameras in the Canon EF Lens Catalog (20D) and the Micro Four Thirds Lens Catalog (E-PM1). Mirrorless cameras, such as the E-PM1, have moreover the advantage that they can use many lenses from other systems via adapters, as they have a relatively short flange to focal plane distance.

Concerning battery life, the 20D gets 700 shots out of its Canon BP-511A battery, while the E-PM1 can take 330 images on a single charge of its Olympus BLS-5 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.		Canon 20D	144 mm	106 mm	72 mm	770 g	700	n	Aug 2004	1,499	ebay.com
2.		Olympus E-PM1	110 mm	64 mm	34 mm	265 g	330	n	Jun 2011	499	ebay.com
3.		Canon 7D II	149 mm	112 mm	78 mm	910 g	670	Y	Sep 2014	1,799	ebay.com
4.		Canon 60D	145 mm	106 mm	79 mm	755 g	1100	Y	Aug 2010	1,399	ebay.com
5.		Canon 7D	148 mm	111 mm	74 mm	860 g	800	Y	Sep 2009	1,699	ebay.com
6.		Canon 50D	146 mm	108 mm	74 mm	822 g	800	Y	Aug 2008	1,299	ebay.com
7.		Canon 40D	146 mm	108 mm	74 mm	822 g	750	n	Aug 2007	1,299	ebay.com
8.		Canon 30D	144 mm	106 mm	74 mm	785 g	750	n	Feb 2006	1,399	ebay.com
9.		Canon XT	127 mm	94 mm	64 mm	540 g	400	n	Feb 2005	899	ebay.com
10.		Canon 10D	150 mm	107 mm	75 mm	850 g	500	n	Feb 2003	1,999	ebay.com
11.		Canon Rebel	142 mm	99 mm	72 mm	649 g	400	n	Aug 2003	899	ebay.com
12.		Nikon D200	147 mm	113 mm	74 mm	920 g	400	Y	Nov 2005	1,699	ebay.com
13.		Olympus E-PM2	110 mm	64 mm	34 mm	269 g	360	n	Sep 2012	499	ebay.com
14.		Olympus E-PL2	114 mm	72 mm	42 mm	362 g	280	n	Jan 2011	599	ebay.com
15.		Olympus E-PL3	110 mm	64 mm	37 mm	313 g	300	n	Jun 2011	599	ebay.com
16.		Olympus E-PL1	115 mm	72 mm	42 mm	334 g	290	n	Feb 2010	599	ebay.com
17.		Panasonic G2	124 mm	84 mm	74 mm	428 g	360	n	Mar 2010	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

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-PM1 was launched at a markedly lower price (by 67 percent) than the 20D, 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 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. 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 Canon 20D features an APS-C sensor and the Olympus E-PM1 a Four Thirds sensor. The sensor area in the E-PM1 is 33 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.6 and 2.0. The sensor in the 20D has a native 3:2 aspect ratio, while the one in the E-PM1 offers a 4:3 aspect.

Despite having a smaller sensor, the E-PM1 offers a higher resolution of 12.2 megapixels, compared with 8.2 MP of the 20D. 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 4.29μm versus 6.42μm for the 20D). However, it should be noted that the E-PM1 is much more recent (by 6 years and 10 months) than the 20D, and its sensor will have benefitted from technological advances during this time that make it possible to gather light more efficiently.

The resolution advantage of the Olympus E-PM1 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the E-PM1 for good quality output (200 dots per inch) amounts to 20.2 x 15.1 inches or 51.2 x 38.4 cm, for very good quality (250 dpi) 16.1 x 12.1 inches or 41 x 30.7 cm, and for excellent quality (300 dpi) 13.4 x 10.1 inches or 34.1 x 25.6 cm. The corresponding values for the Canon 20D are 17.5 x 11.7 inches or 44.5 x 29.7 cm for good quality, 14 x 9.3 inches or 35.6 x 23.7 cm for very good quality, and 11.7 x 7.8 inches or 29.7 x 19.8 cm for excellent quality prints.

The Canon EOS 20D has a native sensitivity range from ISO 100 to ISO 1600, which can be extended to ISO 100-3200. The corresponding ISO settings for the Olympus PEN E-PM1 are ISO 100 to ISO 12800 (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 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 review, the 20D has a notably higher overall DXO score than the E-PM1 (overall score 10 points higher), which gives it an advantage in terms of imaging quality. This advantage is based on 0.9 bits higher color depth, 0.7 EV in additional dynamic range, and 0.5 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.		Canon 20D	APS-C	8.2	3504	2336	none	21.9	11.0	721	62
2.		Olympus E-PM1	Four Thirds	12.2	4032	3024	1080/60i	21.0	10.3	499	52
3.		Canon 7D II	APS-C	20.0	5472	3648	1080/60p	22.4	11.8	1082	70
4.		Canon 60D	APS-C	17.9	5184	3456	1080/30p	22.2	11.5	813	66
5.		Canon 7D	APS-C	17.9	5184	3456	1080/30p	22.0	11.7	854	66
6.		Canon 50D	APS-C	15.1	4752	3168	none	21.8	11.4	696	63
7.		Canon 40D	APS-C	10.1	3888	2592	none	22.1	11.3	703	64
8.		Canon 30D	APS-C	8.2	3504	2336	none	21.5	10.8	736	59
9.		Canon XT	APS-C	8.0	3456	2304	none	21.8	10.8	637	60
10.		Canon 10D	APS-C	6.3	3072	2048	none	21.1	10.9	571	57
11.		Canon Rebel	APS-C	6.3	3072	2048	none	21.0	10.8	544	55
12.		Nikon D200	APS-C	10.0	3872	2592	none	22.3	11.5	583	64
13.		Olympus E-PM2	Four Thirds	15.9	4608	3456	1080/30p	22.7	12.2	932	72
14.		Olympus E-PL2	Four Thirds	12.2	4032	3024	720/30p	21.4	10.2	573	55
15.		Olympus E-PL3	Four Thirds	12.2	4032	3024	1080/60i	20.9	10.3	499	52
16.		Olympus E-PL1	Four Thirds	12.2	4032	3024	720/30p	21.5	10.1	487	54
17.		Panasonic G2	Four Thirds	12.0	4000	3000	720/30p	21.2	10.3	493	53

Many modern cameras are not only capable of taking still images, but also of capturing video footage. The E-PM1 indeed provides for movie recording, while the 20D does not. The highest resolution format that the E-PM1 can use is 1080/60i.

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. For example, the 20D has an optical viewfinder, which can be very useful when shooting in bright sunlight. In contrast, the E-PM1 relies on live view and the rear LCD for framing. That said, the E-PM1 can be equipped with an optional viewfinder – the VF-2. The following table reports on some other key feature differences and similarities of the Canon 20D, the Olympus E-PM1, 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.		Canon 20D	optical	Y	1.8 / 118	fixed	n	1/8000s	5.0/s	Y	n
2.		Olympus E-PM1	optional	n	3.0 / 460	fixed	n	1/4000s	5.5/s	n	Y
3.		Canon 7D II	optical	Y	3.0 / 1040	fixed	n	1/8000s	10.0/s	Y	n
4.		Canon 60D	optical	Y	3.0 / 1040	swivel	n	1/8000s	5.3/s	Y	n
5.		Canon 7D	optical	Y	3.0 / 920	fixed	n	1/8000s	8.0/s	Y	n
6.		Canon 50D	optical	Y	3.0 / 920	fixed	n	1/8000s	6.3/s	Y	n
7.		Canon 40D	optical	Y	3.0 / 230	fixed	n	1/8000s	6.5/s	Y	n
8.		Canon 30D	optical	Y	2.5 / 230	fixed	n	1/8000s	5.0/s	Y	n
9.		Canon XT	optical	n	1.8 / 115	fixed	n	1/4000s	3.0/s	Y	n
10.		Canon 10D	optical	Y	1.8 / 118	fixed	n	1/4000s	3.0/s	Y	n
11.		Canon Rebel	optical	n	1.8 / 118	fixed	n	1/4000s	2.5/s	Y	n
12.		Nikon D200	optical	Y	2.5 / 230	fixed	n	1/8000s	5.0/s	Y	n
13.		Olympus E-PM2	optional	n	3.0 / 460	fixed	Y	1/4000s	8.0/s	n	Y
14.		Olympus E-PL2	optional	n	3.0 / 460	fixed	n	1/4000s	3.0/s	Y	Y
15.		Olympus E-PL3	optional	n	3.0 / 460	tilting	n	1/4000s	5.5/s	n	Y
16.		Olympus E-PL1	optional	n	2.7 / 230	fixed	n	1/2000s	3.0/s	Y	Y
17.		Panasonic G2	1440	n	3.0 / 460	swivel	Y	1/4000s	2.6/s	Y	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 20D has one, while the E-PM1 does not. While the built-in flash of the 20D is not very powerful, it can at times be useful as a fill-in light.

The 20D writes its imaging data to Compact Flash cards, while the E-PM1 uses SDXC 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 Canon EOS 20D and Olympus PEN E-PM1 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.		Canon 20D	Y	- / -	-	-	-	1.1	-	-	-
2.		Olympus E-PM1	Y	stereo / mono	-	-	mini	2.0	-	-	-
3.		Canon 7D II	Y	stereo / mono	Y	Y	mini	3.0	-	-	-
4.		Canon 60D	Y	mono / mono	Y	-	mini	2.0	-	-	-
5.		Canon 7D	Y	mono / -	Y	-	mini	2.0	-	-	-
6.		Canon 50D	Y	- / -	-	-	mini	2.0	-	-	-
7.		Canon 40D	Y	- / -	-	-	-	2.0	-	-	-
8.		Canon 30D	Y	- / -	-	-	-	2.0	-	-	-
9.		Canon XT	Y	- / -	-	-	-	2.0	-	-	-
10.		Canon 10D	Y	- / -	-	-	-	1.1	-	-	-
11.		Canon Rebel	Y	- / -	-	-	-	1.1	-	-	-
12.		Nikon D200	Y	- / -	-	-	-	2.0	-	-	-
13.		Olympus E-PM2	Y	stereo / mono	-	-	mini	2.0	-	-	-
14.		Olympus E-PL2	Y	stereo / -	-	-	mini	2.0	-	-	-
15.		Olympus E-PL3	Y	stereo / -	-	-	mini	2.0	-	-	-
16.		Olympus E-PL1	Y	stereo / -	-	-	mini	2.0	-	-	-
17.		Panasonic G2	Y	stereo / mono	-	-	mini	2.0	-	-	-

Studio photographers will appreciate that the Canon 20D (unlike the E-PM1) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the 20D and the E-PM1 have been discontinued, but can regularly be found used on ebay. The 20D was replaced by the Canon 30D, while the E-PM1 was followed by the Olympus E-PM2. Further information on the features and operation of the 20D and E-PM1 can be found, respectively, in the Canon 20D Manual (free pdf) or the online Olympus E-PM1 Manual.

Review summary

So how do things add up? Which of the two cameras – the Canon 20D or the Olympus E-PM1 – has the upper hand? Is one clearly better than the other? A synthesis of the relative strong points of each of the models is listed below.

Arguments in favor of the Canon EOS 20D:

• Better image quality: Scores markedly higher (10 points) in the DXO overall assessment.
• More dynamic range: Captures a larger spectrum of light and dark details (0.7 EV of extra DR).
• Better low-light sensitivity: Requires less light for good images (0.5 stops ISO advantage).
• Easier framing: Has an optical viewfinder for image composition and settings control.
• Easier setting verification: Features an LCD display on top to control shooting parameters.
• Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
• Longer lasting: Can take more shots (700 versus 330) on a single battery charge.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• Better studio light control: Has a PC Sync socket to connect to professional strobe lights.
• More heavily discounted: Has been available for much longer (launched in August 2004).

Reasons to prefer the Olympus PEN E-PM1:

• More detail: Has more megapixels (12.2 vs 8.2MP), which boosts linear resolution by 20%.
• Broader imaging potential: Can capture not only stills but also 1080/60i video.
• Larger screen: Has a bigger rear LCD (3.0" vs 1.8") for image review and settings control.
• More detailed LCD: Has a higher resolution rear screen (460k vs 118k dots).
• More compact: Is smaller (110x64mm vs 144x106mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 505g or 66 percent) and is thus easier to take along.
• Sharper images: Has stabilization technology built-in to reduce the impact of hand-shake.
• More legacy lens friendly: Can use many non-native lenses via adapters.
• Faster data transfer: Supports a more advanced USB protocol (2.0 vs 1.1).
• More affordable: Was introduced into a lower priced category (67 percent cheaper at launch).
• More modern: Reflects 6 years and 10 months of technical progress since the 20D launch.

If the count of individual advantages (bullet points above) is taken as a guide, the E-PM1 comes out slightly ahead of the 20D (11 : 10 points). However, the pertinence of the various camera strengths will differ across photographers, so that you might want to weigh individual camera traits according to their importance for your own imaging needs before making a camera decision. 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 Canon 20D and the Olympus E-PM1 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 remains partial and cannot reveal, for example, the shooting experience and imaging performance when actually working with the 20D or the E-PM1. 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.		Canon 20D	..	..	..	+ +	..	..	Aug 2004	1,499	ebay.com
2.		Olympus E-PM1	..	86/100	..	71/100	4.5/5	4.5/5	Jun 2011	499	ebay.com
3.		Canon 7D II	4.5/5	+	3.5/5	84/100	4/5	4.5/5	Sep 2014	1,799	ebay.com
4.		Canon 60D	5/5	+	..	79/100	4/5	4.5/5	Aug 2010	1,399	ebay.com
5.		Canon 7D	5/5	+ +	..	84/100	4.5/5	4.5/5	Sep 2009	1,699	ebay.com
6.		Canon 50D	..	+ +	..	+ +	4.5/5	4.5/5	Aug 2008	1,299	ebay.com
7.		Canon 40D	..	+ +	..	+ +	4.5/5	4.5/5	Aug 2007	1,299	ebay.com
8.		Canon 30D	..	+ +	..	+ +	o	..	Feb 2006	1,399	ebay.com
9.		Canon XT	..	80/100	..	+ +	o	..	Feb 2005	899	ebay.com
10.		Canon 10D	..	..	..	+ +	..	..	Feb 2003	1,999	ebay.com
11.		Canon Rebel	..	..	..	+ +	..	..	Aug 2003	899	ebay.com
12.		Nikon D200	..	+ +	..	+ +	o	..	Nov 2005	1,699	ebay.com
13.		Olympus E-PM2	3/5	..	..	77/100	5/5	4.5/5	Sep 2012	499	ebay.com
14.		Olympus E-PL2	3/5	83/100	..	71/100	4.5/5	4.5/5	Jan 2011	599	ebay.com
15.		Olympus E-PL3	3/5	+ +	..	72/100	4.5/5	4/5	Jun 2011	599	ebay.com
16.		Olympus E-PL1	..	86/100	..	69/100	4/5	4.5/5	Feb 2010	599	ebay.com
17.		Panasonic G2	..	..	..	72/100	4/5	4.5/5	Mar 2010	599	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. Also, please note that some of the review sites have changed their methodology and reporting over time.

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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. 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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