Canon 40D vs M3

The Canon EOS 40D and the Canon EOS M3 are two digital cameras that were officially introduced, respectively, in August 2007 and February 2015. The 40D is a DSLR, while the M3 is a mirrorless interchangeable lens camera. Both cameras are equipped with an APS-C sensor. The 40D has a resolution of 10.1 megapixels, whereas the M3 provides 24 MP.

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

Headline Specifications

Canon 40D		Canon M3
Digital single lens reflex		Mirrorless system camera
Canon EF mount lenses		Canon EF-M mount lenses
10.1 MP – APS-C sensor		24 MP – APS-C sensor
no Video		1080/30p Video
ISO 100-1,600 (100 - 3,200)		ISO 100-12,800 (100 - 25,600)
Optical viewfinder		Viewfinder optional
3.0" LCD – 230k dots		3.0" LCD – 1040k dots
Fixed screen (not touch-sensitive)		Tilting touchscreen
6.5 shutter flaps per second		4.2 shutter flaps per second
750 shots per battery charge		250 shots per battery charge
146 x 108 x 74 mm, 822 g		111 x 68 x 44 mm, 366 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Canon EOS 40D and the Canon EOS M3? 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 Canon 40D and the Canon M3 is provided in the side-by-side display below. The two cameras are presented according to their relative size. Three consecutive views from the front, the top, and the rear side are shown. All size dimensions are rounded to the nearest millimeter.

The M3 can be obtained in two different colors (black, white), while the 40D 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 Canon M3 is considerably smaller (52 percent) than the Canon 40D. Moreover, the M3 is substantially lighter (55 percent) than the 40D. In this context, it is worth noting that neither the 40D nor the M3 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. 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 40D gets 750 shots out of its Canon BP-511A battery, while the M3 can take 250 images on a single charge of its Canon LP-E17 power pack.

The table below summarizes the key physical specs of the two cameras alongside a broader set of comparators. If you want to switch the focus of the display and review another camera pair, you can move across to the CAM-parator tool and choose from the broad selection of possible camera comparisons there.

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 40D	146 mm	108 mm	74 mm	822 g	750	n	Aug 2007	1,299	ebay.com
2.		Canon M3	111 mm	68 mm	44 mm	366 g	250	n	Feb 2015	679	ebay.com
3.		Canon 10D	150 mm	107 mm	75 mm	850 g	500	n	Feb 2003	1,999	ebay.com
4.		Canon 20D	144 mm	106 mm	72 mm	770 g	700	n	Aug 2004	1,499	ebay.com
5.		Canon 30D	144 mm	106 mm	74 mm	785 g	750	n	Feb 2006	1,399	ebay.com
6.		Canon 50D	146 mm	108 mm	74 mm	822 g	800	Y	Aug 2008	1,299	ebay.com
7.		Canon 60D	145 mm	106 mm	79 mm	755 g	1100	Y	Aug 2010	1,399	ebay.com
8.		Canon M5	116 mm	89 mm	61 mm	427 g	295	n	Sep 2016	979	ebay.com
9.		Canon M6	112 mm	68 mm	45 mm	390 g	295	n	Feb 2017	779	ebay.com
10.		Canon M100	108 mm	67 mm	35 mm	302 g	295	n	Aug 2017	499	ebay.com
11.		Canon T3	130 mm	100 mm	78 mm	495 g	700	n	Feb 2011	449	ebay.com
12.		Canon T6i	132 mm	101 mm	78 mm	555 g	440	n	Feb 2015	749	ebay.com
13.		Canon T6s	132 mm	101 mm	78 mm	565 g	440	n	Feb 2015	649	ebay.com
14.		Canon XS	126 mm	98 mm	65 mm	502 g	500	n	Jun 2008	449	ebay.com
15.		Canon XSi	129 mm	98 mm	62 mm	524 g	500	n	Jan 2008	799	ebay.com
16.		Canon XTi	127 mm	84 mm	65 mm	556 g	370	n	Aug 2006	799	ebay.com
17.		Nikon D90	132 mm	103 mm	77 mm	703 g	850	n	Aug 2008	1,299	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 M3 was launched at a markedly lower price (by 48 percent) than the 40D, 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 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 tend to be more expensive and lead to bigger and heavier cameras and lenses.

Both cameras under consideration feature an APS-C sensor and have a format factor (sometimes also referred to as "crop factor") of 1.6. Within the spectrum of camera sensors, this places the review cameras among the medium-sized sensor cameras that aim to strike a balance between image quality and portability. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

Technology-wise, the M3 uses a more advanced image processing engine (DIGIC 6) than the 40D (DIGIC 3), with benefits for noise reduction, color accuracy, and processing speed.

While the two cameras under review share the same sensor size, the M3 offers a higher resolution of 24 megapixels, compared with 10.1 MP of the 40D. This megapixels advantage translates into a 54 percent gain in linear resolution. On the other hand, these sensor specs imply that the M3 has a higher pixel density and a smaller size of the individual pixel (with a pixel pitch of 3.72μm versus 5.73μm for the 40D). However, it should be noted that the M3 is much more recent (by 7 years and 5 months) than the 40D, and its sensor will have benefitted from technological advances during this time that compensate for the smaller pixel size.

The resolution advantage of the Canon M3 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the M3 for good quality output (200 dots per inch) amounts to 30 x 20 inches or 76.2 x 50.8 cm, for very good quality (250 dpi) 24 x 16 inches or 61 x 40.6 cm, and for excellent quality (300 dpi) 20 x 13.3 inches or 50.8 x 33.9 cm. The corresponding values for the Canon 40D are 19.4 x 13 inches or 49.4 x 32.9 cm for good quality, 15.6 x 10.4 inches or 39.5 x 26.3 cm for very good quality, and 13 x 8.6 inches or 32.9 x 21.9 cm for excellent quality prints.

The M3 has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

The Canon EOS 40D 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 Canon EOS M3 are ISO 100 to ISO 12800, with the possibility to increase the ISO range to 100-25600.

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 determines an overall sensor rating, as well as sub-scores for low-light sensitivity ("DXO Sports"), dynamic range ("DXO Landscape"), and color depth ("DXO Portrait"). Of the two cameras under consideration, the M3 has a markedly higher DXO score than the 40D (overall score 8 points higher), which will translate into better image quality. The advantage is based on 0.7 bits higher color depth, 0.5 EV in additional dynamic range, and 0.7 stops in additional low light sensitivity. 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.		Canon 40D	APS-C	10.1	3888	2592	none	22.1	11.3	703	64
2.		Canon M3	APS-C	24.0	6000	4000	1080/30p	22.8	11.8	1169	72
3.		Canon 10D	APS-C	6.3	3072	2048	none	21.1	10.9	571	57
4.		Canon 20D	APS-C	8.2	3504	2336	none	21.9	11.0	721	62
5.		Canon 30D	APS-C	8.2	3504	2336	none	21.5	10.8	736	59
6.		Canon 50D	APS-C	15.1	4752	3168	none	21.8	11.4	696	63
7.		Canon 60D	APS-C	17.9	5184	3456	1080/30p	22.2	11.5	813	66
8.		Canon M5	APS-C	24.0	6000	4000	1080/60p	23.4	12.4	1262	77
9.		Canon M6	APS-C	24.0	6000	4000	1080/60p	23.4	12.6	1317	78
10.		Canon M100	APS-C	24.0	6000	4000	1080/60p	23.5	12.9	1272	78
11.		Canon T3	APS-C	12.2	4272	2848	720/30p	21.9	11.0	755	62
12.		Canon T6i	APS-C	24.0	6000	4000	1080/30p	22.7	12.0	919	71
13.		Canon T6s	APS-C	24.0	6000	4000	1080/30p	22.6	12.0	915	70
14.		Canon XS	APS-C	10.1	3888	2592	none	22.0	10.9	719	62
15.		Canon XSi	APS-C	12.2	4272	2848	none	21.9	10.8	692	61
16.		Canon XTi	APS-C	10.1	3888	2592	none	22.1	11.0	664	62
17.		Nikon D90	APS-C	12.2	4288	2848	720/24p	22.7	12.5	977	73

Many modern cameras cannot only take still pictures, but also record videos. The M3 indeed provides for movie recording, while the 40D does not. The highest resolution format that the M3 can use is 1080/30p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a range of features. For example, the 40D has an optical viewfinder, which can be very useful when shooting in bright sunlight. In contrast, the M3 relies on live view and the rear LCD for framing. That said, the M3 can be equipped with an optional viewfinder – the EVF-DC1. The table below summarizes some of the other core capabilities of the Canon 40D and Canon M3 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.		Canon 40D	optical	Y	3.0 / 230	fixed	n	1/8000s	6.5/s	Y	n
2.		Canon M3	optional	n	3.0 / 1040	tilting	Y	1/4000s	4.2/s	Y	n
3.		Canon 10D	optical	Y	1.8 / 118	fixed	n	1/4000s	3.0/s	Y	n
4.		Canon 20D	optical	Y	1.8 / 118	fixed	n	1/8000s	5.0/s	Y	n
5.		Canon 30D	optical	Y	2.5 / 230	fixed	n	1/8000s	5.0/s	Y	n
6.		Canon 50D	optical	Y	3.0 / 920	fixed	n	1/8000s	6.3/s	Y	n
7.		Canon 60D	optical	Y	3.0 / 1040	swivel	n	1/8000s	5.3/s	Y	n
8.		Canon M5	2360	n	3.2 / 1620	tilting	Y	1/4000s	9.0/s	Y	n
9.		Canon M6	optional	n	3.0 / 1040	tilting	Y	1/4000s	9.0/s	Y	n
10.		Canon M100	none	n	3.0 / 1040	tilting	Y	1/4000s	6.1/s	Y	n
11.		Canon T3	optical	n	2.7 / 230	fixed	n	1/4000s	3.0/s	Y	n
12.		Canon T6i	optical	n	3.0 / 1040	swivel	Y	1/4000s	5.0/s	Y	n
13.		Canon T6s	optical	Y	3.0 / 1040	swivel	Y	1/4000s	5.0/s	Y	n
14.		Canon XS	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
15.		Canon XSi	optical	n	3.0 / 230	fixed	n	1/4000s	3.5/s	Y	n
16.		Canon XTi	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
17.		Nikon D90	optical	Y	3.0 / 920	fixed	n	1/4000s	4.5/s	Y	n
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that is present on the 40D, but is missing on the M3 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 40D writes its imaging data to Compact Flash cards, while the M3 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 40D and Canon EOS M3 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 40D	Y	- / -	-	-	-	2.0	-	-	-
2.		Canon M3	Y	stereo / mono	Y	-	mini	2.0	Y	Y	-
3.		Canon 10D	Y	- / -	-	-	-	1.1	-	-	-
4.		Canon 20D	Y	- / -	-	-	-	1.1	-	-	-
5.		Canon 30D	Y	- / -	-	-	-	2.0	-	-	-
6.		Canon 50D	Y	- / -	-	-	mini	2.0	-	-	-
7.		Canon 60D	Y	mono / mono	Y	-	mini	2.0	-	-	-
8.		Canon M5	Y	stereo / mono	Y	-	mini	2.0	Y	Y	Y
9.		Canon M6	Y	stereo / mono	Y	-	mini	2.0	Y	Y	Y
10.		Canon M100	-	stereo / mono	-	-	micro	2.0	Y	Y	Y
11.		Canon T3	Y	stereo / mono	-	-	mini	2.0	-	-	-
12.		Canon T6i	Y	stereo / mono	Y	-	mini	2.0	Y	Y	-
13.		Canon T6s	Y	stereo / mono	Y	-	mini	2.0	Y	Y	-
14.		Canon XS	Y	- / -	-	-	-	2.0	-	-	-
15.		Canon XSi	Y	- / -	-	-	mini	2.0	-	-	-
16.		Canon XTi	Y	- / -	-	-	-	2.0	-	-	-
17.		Nikon D90	Y	mono / mono	-	-	mini	2.0	-	-	-

It is notable that the M3 offers wifi support, which can be a very convenient means to transfer image data to an off-camera location. In contrast, the 40D does not provide wifi capability.

Studio photographers will appreciate that the Canon 40D (unlike the M3) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the 40D and the M3 have been discontinued, but can regularly be found used on ebay. The 40D was replaced by the Canon 50D, while the M3 was followed by the Canon M6. Further information on the features and operation of the 40D and M3 can be found, respectively, in the Canon 40D Manual (free pdf) or the online Canon M3 Manual.

Review summary

So what is the bottom line? Is there a clear favorite between the Canon 40D and the Canon M3? Which camera is better? The listing below highlights the relative strengths of the two models.

Advantages of the Canon EOS 40D:

• 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.
• Faster burst: Shoots at higher frequency (6.5 vs 4.2 flaps/sec) to capture the decisive moment.
• Longer lasting: Can take more shots (750 versus 250) on a single battery charge.
• 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 2007).

Reasons to prefer the Canon EOS M3:

• More detail: Has more megapixels (24 vs 10.1MP), which boosts linear resolution by 54%.
• Better image quality: Scores markedly higher (8 points) in the DXO overall evaluation.
• Better low-light sensitivity: Can shoot in dim conditions (0.7 stops ISO advantage).
• Better jpgs: Has a more modern image processing engine (DIGIC 6 vs DIGIC 3).
• Broader imaging potential: Can capture not only stills but also 1080/30p video.
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• More detailed LCD: Has a higher resolution rear screen (1040k vs 230k dots).
• More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
• Fewer buttons to press: Has a touchscreen to facilitate handling and shooting adjustments.
• More selfie-friendly: Has an articulated screen that can be turned to be front-facing.
• More compact: Is smaller (111x68mm vs 146x108mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 456g or 55 percent) and is thus easier to take along.
• 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 affordable: Was introduced into a lower priced category (48 percent cheaper at launch).
• More modern: Reflects 7 years and 5 months of technical progress since the 40D launch.

If the count of individual advantages (bullet points above) is taken as a guide, the M3 is the clear winner of the contest (17 : 7 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 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 Canon 40D and the Canon M3 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 the spec-sheets of cameras can offer a general idea of their imaging potential, it remains incomplete and does no justice, for example, to the way the 40D or the M3 perform in practice. User reviews that are available, for instance, at amazon can sometimes shed light on these issues, but such feedback is all too often partial, inconsistent, and inaccurate.

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 40D	..	+ +	..	+ +	4.5/5	4.5/5	Aug 2007	1,299	ebay.com
2.		Canon M3	4/5	o	..	75/100	4.5/5	4/5	Feb 2015	679	ebay.com
3.		Canon 10D	..	..	..	+ +	..	..	Feb 2003	1,999	ebay.com
4.		Canon 20D	..	..	..	+ +	..	..	Aug 2004	1,499	ebay.com
5.		Canon 30D	..	+ +	..	+ +	o	..	Feb 2006	1,399	ebay.com
6.		Canon 50D	..	+ +	..	+ +	4.5/5	4.5/5	Aug 2008	1,299	ebay.com
7.		Canon 60D	5/5	+	..	79/100	4/5	4.5/5	Aug 2010	1,399	ebay.com
8.		Canon M5	4/5	+	4/5	82/100	4/5	4/5	Sep 2016	979	ebay.com
9.		Canon M6	..	..	..	80/100	4/5	4/5	Feb 2017	779	ebay.com
10.		Canon M100	3/5	+	..	..	4/5	3.5/5	Aug 2017	499	ebay.com
11.		Canon T3	..	80/100	..	69/100	4/5	4.5/5	Feb 2011	449	ebay.com
12.		Canon T6i	5/5	..	..	75/100	4.5/5	4.5/5	Feb 2015	749	ebay.com
13.		Canon T6s	5/5	+	..	77/100	4.5/5	4.5/5	Feb 2015	649	ebay.com
14.		Canon XS	..	82/100	..	+ +	3.5/5	4.5/5	Jun 2008	449	ebay.com
15.		Canon XSi	..	+ +	..	+ +	4/5	4.5/5	Jan 2008	799	ebay.com
16.		Canon XTi	..	+ +	..	+ +	o	4/5	Aug 2006	799	ebay.com
17.		Nikon D90	..	+ +	..	+ +	4/5	4.5/5	Aug 2008	1,299	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

Care should be taken when interpreting the review scores above, though. The assessments were made in relation to similar cameras of the same technological generation. Hence, a score should always be seen in the context of the camera's market launch date and its price, 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.

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Other camera comparisons

Did this review help to inform your camera decision process? In case you are interested in seeing how other cameras pair up, just make a corresponding selection in the search boxes below. Alternatively, you can follow any of the listed hyperlinks for comparisons that others found interesting.

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