Canon G15 vs XTi

The Canon PowerShot G15 and the Canon EOS Rebel XTi (labelled Canon 400D in some countries) are two digital cameras that were officially introduced, respectively, in September 2012 and August 2006. The G15 is a fixed lens compact, while the XTi is a DSLR. The cameras are based on a 1/1.7-inch (G15) and an APS-C (XTi) sensor. The G15 has a resolution of 12 megapixels, whereas the XTi provides 10.1 MP.

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

Headline Specifications

Canon G15		Canon XTi
Fixed lens compact camera		Digital single lens reflex
28-140mm f/1.8-2.8		Canon EF mount lenses
12 MP – 1/1.7" sensor		10.1 MP – APS-C sensor
1080/24p Video		no Video
ISO 80-12,800		ISO 100-1,600
Optical viewfinder		Optical viewfinder
3.0" LCD – 922k dots		2.5" LCD – 230k dots
Fixed screen (not touch-sensitive)		Fixed screen (not touch-sensitive)
2.1 shutter flaps per second		3 shutter flaps per second
350 shots per battery charge		370 shots per battery charge
107 x 76 x 40 mm, 352 g		127 x 84 x 65 mm, 556 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Canon PowerShot G15 and the Canon EOS Rebel XTi? 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 Canon G15 and the Canon XTi. 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 width, height and depth 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 Canon XTi is notably larger (31 percent) than the Canon G15. In this context, it is worth noting that neither the G15 nor the XTi are weather-sealed.

The above size and weight comparisons are to some extent incomplete and possibly misleading, as the G15 has a lens built in, whereas the XTi is an interchangeable lens camera that requires a separate lens. Attaching the latter will add extra weight and bulk to the setup. You can compare the optics available for the XTi and their specifications in the Canon EF Lens Catalog.

Concerning battery life, the G15 gets 350 shots out of its Canon NB-10L battery, while the XTi can take 370 images on a single charge of its Canon NB-2LH power pack.

The adjacent table lists the principal physical characteristics of the two cameras alongside a wider set of alternatives. If you would like to visualize and compare a different camera combination, you can navigate to the CAM-parator app and make your selection from a broad list of cameras there.

Body Specifications

		Camera Model	Camera Width	Camera Height	Camera Depth	Camera Weight	Battery Life	Weather Sealing	Camera Launch	Launch Price	Street Price
1.		Canon G15	107 mm	76 mm	40 mm	352 g	350	n	Sep 2012	US$ 499	ebay.com
2.		Canon XTi	127 mm	84 mm	65 mm	556 g	370	n	Aug 2006	US$ 799	ebay.com
3.		Canon 40D	146 mm	108 mm	74 mm	822 g	750	n	Aug 2007	US$ 1 299	ebay.com
4.		Canon G12	112 mm	76 mm	48 mm	401 g	370	n	Sep 2010	US$ 499	ebay.com
5.		Canon G16	109 mm	76 mm	40 mm	356 g	360	n	Aug 2013	US$ 549	ebay.com
6.		Canon S120	100 mm	59 mm	29 mm	217 g	230	n	Aug 2013	US$ 449	ebay.com
7.		Canon SX50	123 mm	87 mm	106 mm	595 g	315	n	Sep 2012	US$ 429	ebay.com
8.		Canon SX60	128 mm	93 mm	114 mm	650 g	340	n	Sep 2014	US$ 549	ebay.com
9.		Canon T3	130 mm	100 mm	78 mm	495 g	700	n	Feb 2011	US$ 449	ebay.com
10.		Canon T4i	133 mm	100 mm	79 mm	575 g	440	n	Jun 2012	US$ 849	ebay.com
11.		Canon XS	126 mm	98 mm	65 mm	502 g	500	n	Jun 2008	US$ 449	ebay.com
12.		Canon XT	127 mm	94 mm	64 mm	540 g	400	n	Feb 2005	US$ 899	ebay.com
13.		Fujifilm X10	117 mm	70 mm	57 mm	350 g	270	n	Sep 2011	US$ 599	ebay.com
14.		Fujifilm X20	117 mm	70 mm	57 mm	353 g	270	n	Jan 2013	US$ 599	ebay.com
15.		Nikon P7800	119 mm	78 mm	50 mm	399 g	350	n	Sep 2013	US$ 549	ebay.com
16.		Panasonic FZ150	124 mm	82 mm	92 mm	528 g	410	n	Aug 2011	US$ 499	ebay.com
17.		Panasonic LX7	111 mm	68 mm	46 mm	298 g	330	n	Jul 2012	US$ 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 listed launch prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The G15 was launched at a lower price than the XTi, despite having a lens built in. 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 imaging sensor is at the core of digital cameras and its size is one of the main determining factors 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. 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 more expensive and lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Canon G15 features a 1/1.7-inch sensor and the Canon XTi an APS-C sensor. The sensor area in the XTi is 665 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 4.6 and 1.6. The sensor in the G15 has a native 4:3 aspect ratio, while the one in the XTi offers a 3:2 aspect.

In terms of chip-set technology, the G15 uses a more advanced image processing engine (DIGIC 5) than the XTi (DIGIC II), with benefits for noise reduction, color accuracy, and processing speed.

Despite having a smaller sensor, the Canon G15 offers a higher resolution of 12 megapixels, compared with 10.1 MP of the Canon XTi. 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 1.89μm versus 5.71μm for the XTi). However, it should be noted that the G15 is much more recent (by 6 years) than the XTi, 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 Canon G15 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the G15 for good quality output (200 dots per inch) amounts to 20 x 15 inches or 50.8 x 38.1 cm, for very good quality (250 dpi) 16 x 12 inches or 40.6 x 30.5 cm, and for excellent quality (300 dpi) 13.3 x 10 inches or 33.9 x 25.4 cm. The corresponding values for the Canon XTi 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 Canon PowerShot G15 has a native sensitivity range from ISO 80 to ISO 12800. The corresponding ISO settings for the Canon EOS Rebel XTi are ISO 100 to ISO 1600 (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.

For many cameras, data on sensor performance has been reported by DXO Mark. 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 XTi offers substantially better image quality than the G15 (overall score 16 points higher). The advantage is based on 2.2 bits higher color depth, 0.5 EV of lower dynamic range, and 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.		Canon G15	1/1.7	12.0	4000	3000	1080/24p	19.9	11.5	165	46
2.		Canon XTi	APS-C	10.1	3888	2592	none	22.1	11.0	664	62
3.		Canon 40D	APS-C	10.1	3888	2592	none	22.1	11.3	703	64
4.		Canon G12	1/1.7	10.0	3648	2736	720/24p	20.4	11.2	161	47
5.		Canon G16	1/1.7	12.0	4000	3000	1080/60p	21.0	11.7	230	54
6.		Canon S120	1/1.7	12.0	4000	3000	1080/60p	21.3	11.9	246	56
7.		Canon SX50	1/2.3	12.0	4000	3000	1080/24p	20.3	11.2	179	47
8.		Canon SX60	1/2.3	14.2	4608	3072	1080/60p	19.2	10.8	127	39
9.		Canon T3	APS-C	12.2	4272	2848	720/30p	21.9	11.0	755	62
10.		Canon T4i	APS-C	17.9	5184	3456	1080/30p	21.7	11.2	722	62
11.		Canon XS	APS-C	10.1	3888	2592	none	22.0	10.9	719	62
12.		Canon XT	APS-C	8.0	3456	2304	none	21.8	10.8	637	60
13.		Fujifilm X10	2/3	12.0	4000	3000	1080/30p	20.5	11.3	245	50
14.		Fujifilm X20	2/3	12.0	4000	3000	1080/60p	20.1	10.9	-462	46
15.		Nikon P7800	1/1.7	12.0	4000	3000	1080/30p	21.2	11.7	200	54
16.		Panasonic FZ150	1/2.3	12.0	4000	3000	1080/60p	19.4	10.9	132	40
17.		Panasonic LX7	1/1.7	10.0	3648	2736	1080/60p	20.7	11.7	147	50
Note: DXO values in italics represent estimates based on sensor size and age.

Many modern cameras cannot only take still pictures, but also record videos. The G15 indeed provides movie recording capabilities, while the XTi does not. The highest resolution format that the G15 can use is 1080/24p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a range of features. The G15 and the XTi 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 adjacent table lists some of the other core features of the Canon G15 and Canon XTi 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.		Canon G15	optical	n	3.0 / 922	fixed	n	1/4000s	2.1/s	Y	Y
2.		Canon XTi	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
3.		Canon 40D	optical	Y	3.0 / 230	fixed	n	1/8000s	6.5/s	Y	n
4.		Canon G12	optical	n	2.8 / 461	swivel	n	1/4000s	1.1/s	Y	Y
5.		Canon G16	optical	n	3.0 / 922	fixed	n	1/4000s	2.2/s	Y	Y
6.		Canon S120	none	n	3.0 / 922	fixed	Y	1/2000s	12.1/s	Y	Y
7.		Canon SX50	202	n	3.0 / 461	swivel	n	1/2000s	2.2/s	Y	Y
8.		Canon SX60	922	n	3.0 / 922	swivel	n	1/2000s	6.4/s	Y	Y
9.		Canon T3	optical	n	2.7 / 230	fixed	n	1/4000s	3.0/s	Y	n
10.		Canon T4i	optical	n	3.0 / 1040	swivel	Y	1/4000s	5.0/s	Y	n
11.		Canon XS	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
12.		Canon XT	optical	n	1.8 / 115	fixed	n	1/4000s	3.0/s	Y	n
13.		Fujifilm X10	optical	n	2.8 / 460	fixed	n	1/4000s	10.0/s	Y	Y
14.		Fujifilm X20	optical	n	2.8 / 460	fixed	n	1/4000s	12.0/s	Y	Y
15.		Nikon P7800	921	n	3.0 / 921	swivel	n	1/4000s	8.0/s	Y	Y
16.		Panasonic FZ150	202	n	3.0 / 460	swivel	n	1/2000s	12.0/s	Y	Y
17.		Panasonic LX7	optional	n	3.0 / 920	fixed	n	1/4000s	11.0/s	Y	Y
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

The G15 writes its imaging data to SDXC cards, while the XTi uses Compact Flash 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 PowerShot G15 and Canon EOS Rebel XTi 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 G15	Y	stereo / mono	-	-	mini	2.0	-	-	-
2.		Canon XTi	Y	- / -	-	-	-	2.0	-	-	-
3.		Canon 40D	Y	- / -	-	-	-	2.0	-	-	-
4.		Canon G12	Y	stereo / mono	-	-	mini	2.0	-	-	-
5.		Canon G16	Y	stereo / mono	-	-	mini	2.0	Y	-	-
6.		Canon S120	-	stereo / mono	-	-	mini	2.0	Y	-	-
7.		Canon SX50	Y	stereo / mono	-	-	mini	2.0	-	-	-
8.		Canon SX60	Y	stereo / mono	Y	-	mini	2.0	Y	Y	-
9.		Canon T3	Y	stereo / mono	-	-	mini	2.0	-	-	-
10.		Canon T4i	Y	stereo / mono	Y	-	mini	2.0	-	-	-
11.		Canon XS	Y	- / -	-	-	-	2.0	-	-	-
12.		Canon XT	Y	- / -	-	-	-	2.0	-	-	-
13.		Fujifilm X10	Y	stereo / mono	-	-	mini	2.0	-	-	-
14.		Fujifilm X20	Y	stereo / mono	-	-	micro	2.0	-	-	-
15.		Nikon P7800	Y	stereo / mono	Y	-	mini	2.0	-	-	-
16.		Panasonic FZ150	Y	stereo / -	-	-	mini	2.0	-	-	-
17.		Panasonic LX7	Y	stereo / mono	-	-	mini	2.0	-	-	-

Both the G15 and the XTi have been discontinued, but can regularly be found used on ebay. The XTi was replaced by the Canon Xsi, while the G15 was followed by the Canon G16. Further information on the features and operation of the G15 and XTi can be found, respectively, in the Canon G15 Manual (free pdf) or the online Canon XTi Manual.

Review summary

So how do things add up? Is there a clear favorite between the Canon G15 and the Canon XTi? Which camera is better? A synthesis of the relative strong points of each of the models is listed below.

Advantages of the Canon PowerShot G15:

• More detail: Offers more megapixels (12 vs 10.1MP) with a 7% higher linear resolution.
• Better jpgs: Has a more modern image processing engine (DIGIC 5 vs DIGIC II).
• Broader imaging potential: Can record not only still images but also 1080/24p movies.
• Larger screen: Has a bigger rear LCD (3.0" vs 2.5") for image review and settings control.
• More detailed LCD: Has a higher resolution rear screen (922k vs 230k dots).
• Ready to shoot: Comes with a built-in lens, while the XTi requires a separate lens.
• More compact: Is smaller (107x76mm vs 127x84mm) and thus needs less room in the bag.
• Less heavy: Is lighter even though it comes with a built-in lens (unlike the XTi).
• Sharper images: Has hand-shake reducing image stabilization built-in.
• More affordable: Was introduced at a lower price, despite coming with a built-in lens.
• More modern: Reflects 6 years of technical progress since the XTi launch.

Arguments in favor of the Canon EOS Rebel XTi:

• Better image quality: Scores substantially higher (16 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (2.2 bits more color depth).
• Better low-light sensitivity: Can shoot in dim conditions (2 stops ISO advantage).
• Faster burst: Shoots at higher frequency (3 vs 2.1 flaps/sec) to capture the decisive moment.
• More flexible: Makes it possible to change lenses and thus to use specialty optics.
• More heavily discounted: Has been around for much longer (launched in August 2006).

If the count of relative strengths (bullet points above) is taken as a measure, the G15 is the clear winner of the match-up (11 : 6 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 G15 and the Canon XTi place the cameras among the top in their class? Find out in the latest Best Travel-Zoom Camera and Best DSLR Camera listings whether the two cameras rank among the cream of the crop.

In any case, while the comparison of technical specifications can provide a useful overview of the capabilities of different cameras, it remains partial and cannot reveal, for example, the shooting experience and imaging performance when actually working with the G15 or the XTi. 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	Street Price
1.		Canon G15	4/5	+	..	76/100	4.5/5	4.5/5	Sep 2012	US$ 499	ebay.com
2.		Canon XTi	..	+ +	..	+ +	o	4/5	Aug 2006	US$ 799	ebay.com
3.		Canon 40D	..	+ +	..	+ +	4.5/5	4.5/5	Aug 2007	US$ 1 299	ebay.com
4.		Canon G12	4/5	+	..	73/100	4.5/5	4.5/5	Sep 2010	US$ 499	ebay.com
5.		Canon G16	4/5	+	..	..	4.5/5	4.5/5	Aug 2013	US$ 549	ebay.com
6.		Canon S120	..	+ +	..	..	4.5/5	4.5/5	Aug 2013	US$ 449	ebay.com
7.		Canon SX50	3/5	+ +	..	72/100	4.5/5	4.5/5	Sep 2012	US$ 429	ebay.com
8.		Canon SX60	3/5	+ +	..	75/100	4/5	4.5/5	Sep 2014	US$ 549	ebay.com
9.		Canon T3	..	80/100	..	69/100	4/5	4.5/5	Feb 2011	US$ 449	ebay.com
10.		Canon T4i	4/5	+ +	..	77/100	4.5/5	4.5/5	Jun 2012	US$ 849	ebay.com
11.		Canon XS	..	82/100	..	+ +	3.5/5	4.5/5	Jun 2008	US$ 449	ebay.com
12.		Canon XT	..	80/100	..	+ +	o	..	Feb 2005	US$ 899	ebay.com
13.		Fujifilm X10	..	..	..	76/100	4/5	4.5/5	Sep 2011	US$ 599	ebay.com
14.		Fujifilm X20	4/5	+ +	..	77/100	4.5/5	5/5	Jan 2013	US$ 599	ebay.com
15.		Nikon P7800	3/5	..	..	..	4/5	4.5/5	Sep 2013	US$ 549	ebay.com
16.		Panasonic FZ150	3/5	+ +	..	76/100	4/5	4.5/5	Aug 2011	US$ 499	ebay.com
17.		Panasonic LX7	3/5	+ +	..	75/100	4/5	4.5/5	Jul 2012	US$ 499	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. Hence, a score should always be seen in the context of the camera's market launch date and its price, 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? In case you would like to check on the differences and similarities of other camera models, just make your choice using the following search menu. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored.

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