Canon XT vs Pentax 645D

The Canon EOS Rebel XT (called Canon 350D in some regions) and the Pentax 645D are two digital cameras that were announced, respectively, in February 2005 and March 2010. Both are DSLR (Digital Single Lens Reflex) cameras that are based on an APS-C (XT) and a medium format (645D) sensor. The Canon has a resolution of 8 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

Canon XT		Pentax 645D
Digital single lens reflex		Digital single lens reflex
Canon EF mount lenses		Pentax 645 mount lenses
8 MP – APS-C sensor		39.5 MP – Medium Format sensor
no Video		no Video
ISO 100-1,600		ISO 100-1,600
Optical viewfinder		Optical viewfinder
1.8" LCD – 115k dots		3.0" LCD – 921k dots
Fixed screen (not touch-sensitive)		Fixed screen (not touch-sensitive)
3 shutter flaps per second		1.1 shutter flaps per second
not weather sealed		Weathersealed body
400 shots per battery charge		800 shots per battery charge
127 x 94 x 64 mm, 540 g		156 x 117 x 119 mm, 1480 g

Check XT offers at
ebay.com
Check 645D offers at
ebay.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Canon EOS Rebel XT 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

An illustration of the physical size and weight of the Canon XT and the Pentax 645D is provided 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 size dimensions are rounded to the nearest millimeter.

The XT can be obtained in two different colors (black, silver), while the 645D 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 Pentax 645D is considerably larger (53 percent) than the Canon XT. Moreover, the 645D is substantially heavier (174 percent) than the XT. It is noteworthy in this context that the 645D is splash and dust-proof, while the XT 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 XT gets 400 shots out of its Canon NB-2LH 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. 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 XT	127 mm	94 mm	64 mm	540 g	400	n	Feb 2005	899	ebay.com
2.		Pentax 645D	156 mm	117 mm	119 mm	1480 g	800	Y	Mar 2010	9,995	ebay.com
3.		Canon 77D	131 mm	100 mm	76 mm	540 g	600	n	Feb 2017	899	ebay.com
4.		Canon T6i	132 mm	101 mm	78 mm	555 g	440	n	Feb 2015	749	ebay.com
5.		Canon T6s	132 mm	101 mm	78 mm	565 g	440	n	Feb 2015	649	ebay.com
6.		Canon T4i	133 mm	100 mm	79 mm	575 g	440	n	Jun 2012	849	ebay.com
7.		Canon 1D X	158 mm	168 mm	83 mm	1551 g	1120	Y	Oct 2011	6,799	ebay.com
8.		Canon 1D Mark IV	156 mm	157 mm	80 mm	1230 g	1500	Y	Oct 2009	4,999	ebay.com
9.		Canon T1i	129 mm	98 mm	62 mm	520 g	400	n	Mar 2009	799	ebay.com
10.		Canon XSi	129 mm	98 mm	62 mm	524 g	500	n	Jan 2008	799	ebay.com
11.		Canon 30D	144 mm	106 mm	74 mm	785 g	750	n	Feb 2006	1,399	ebay.com
12.		Canon XTi	127 mm	84 mm	65 mm	556 g	370	n	Aug 2006	799	ebay.com
13.		Canon 20D	144 mm	106 mm	72 mm	770 g	700	n	Aug 2004	1,499	ebay.com
14.		Canon Rebel	142 mm	99 mm	72 mm	649 g	400	n	Aug 2003	899	ebay.com
15.		Leica S Typ 006	160 mm	120 mm	80 mm	1260 g	..	Y	Sep 2012	21,950	ebay.com
16.		Nikon D3S	160 mm	157 mm	88 mm	1240 g	4200	Y	Oct 2009	5,199	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

Any camera decision will naturally be influenced heavily by the price. 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 XT was launched at a markedly lower price (by 91 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. 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. All other things equal, a large sensor will have larger individual pixel-units that offer better low-light sensitivity, wider dynamic range, and 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 Canon XT features an APS-C sensor and the Pentax 645D a medium format sensor. The sensor area in the 645D is 341 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.6 and 0.79. The sensor in the XT has a native 3:2 aspect ratio, while the one in the 645D offers a 4:3 aspect.

With 39.5MP, the 645D offers a higher resolution than the XT (8MP), but the 645D has smaller individual pixels (pixel pitch of 6.06μm versus 6.41μm for the XT). Yet, the 645D is a much more recent model (by 5 years) than the XT, and its sensor will have benefitted from technological advances during this time that 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 Canon XT are 17.3 x 11.5 inches or 43.9 x 29.3 cm for good quality, 13.8 x 9.2 inches or 35.1 x 23.4 cm for very good quality, and 11.5 x 7.7 inches or 29.3 x 19.5 cm for excellent quality prints.

The Canon EOS Rebel XT 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 XT 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.

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"). Of the two cameras under consideration, the 645D offers substantially better image quality than the XT (overall score 22 points higher). The advantage is based on 2.8 bits higher color depth, 1.8 EV in additional dynamic range, and 1 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 XT	APS-C	8.0	3456	2304	none	21.8	10.8	637	60
2.		Pentax 645D	Medium Format	39.5	7264	5440	none	24.6	12.6	1262	82
3.		Canon 77D	APS-C	24.0	6000	4000	1080/60p	23.6	13.3	971	78
4.		Canon T6i	APS-C	24.0	6000	4000	1080/30p	22.7	12.0	919	71
5.		Canon T6s	APS-C	24.0	6000	4000	1080/30p	22.6	12.0	915	70
6.		Canon T4i	APS-C	17.9	5184	3456	1080/30p	21.7	11.2	722	62
7.		Canon 1D X	Full Frame	17.9	5184	3456	1080/30p	23.8	11.8	2786	82
8.		Canon 1D Mark IV	APS-H	16.0	4896	3264	1080/30p	22.8	12.0	1320	74
9.		Canon T1i	APS-C	15.1	4752	3168	1080/20p	21.7	11.5	663	63
10.		Canon XSi	APS-C	12.2	4272	2848	none	21.9	10.8	692	61
11.		Canon 30D	APS-C	8.2	3504	2336	none	21.5	10.8	736	59
12.		Canon XTi	APS-C	10.1	3888	2592	none	22.1	11.0	664	62
13.		Canon 20D	APS-C	8.2	3504	2336	none	21.9	11.0	721	62
14.		Canon Rebel	APS-C	6.3	3072	2048	none	21.0	10.8	544	55
15.		Leica S Typ 006	Medium Format	37.5	7500	5000	none	23.9	12.2	824	76
16.		Nikon D3S	Full Frame	12.1	4256	2832	720/24p	23.5	12.0	3253	82
17.		Pentax 645Z	Medium Format	51.1	8256	6192	1080/60i	26.0	14.7	4505	101

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. The XT 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 XT (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 0.49x), 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 Canon XT and Pentax 645D 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 XT	optical	n	1.8 / 115	fixed	n	1/4000s	3.0/s	Y	n
2.		Pentax 645D	optical	Y	3.0 / 921	fixed	n	1/4000s	1.1/s	n	n
3.		Canon 77D	optical	Y	3.0 / 1040	swivel	Y	1/4000s	6.0/s	Y	n
4.		Canon T6i	optical	n	3.0 / 1040	swivel	Y	1/4000s	5.0/s	Y	n
5.		Canon T6s	optical	Y	3.0 / 1040	swivel	Y	1/4000s	5.0/s	Y	n
6.		Canon T4i	optical	n	3.0 / 1040	swivel	Y	1/4000s	5.0/s	Y	n
7.		Canon 1D X	optical	Y	3.2 / 1040	fixed	n	1/8000s	14.0/s	n	n
8.		Canon 1D Mark IV	optical	Y	3.0 / 920	fixed	n	1/8000s	10.0/s	n	n
9.		Canon T1i	optical	n	3.0 / 920	fixed	n	1/4000s	3.4/s	Y	n
10.		Canon XSi	optical	n	3.0 / 230	fixed	n	1/4000s	3.5/s	Y	n
11.		Canon 30D	optical	Y	2.5 / 230	fixed	n	1/8000s	5.0/s	Y	n
12.		Canon XTi	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
13.		Canon 20D	optical	Y	1.8 / 118	fixed	n	1/8000s	5.0/s	Y	n
14.		Canon Rebel	optical	n	1.8 / 118	fixed	n	1/4000s	2.5/s	Y	n
15.		Leica S Typ 006	optical	Y	3.0 / 922	fixed	n	1/4000s	1.5/s	n	n
16.		Nikon D3S	optical	Y	3.0 / 921	fixed	n	1/8000s	11.0/s	n	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 XT has one, while the 645D does not. While the built-in flash of the XT 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 XT writes its imaging data to Compact Flash cards, while the 645D uses SDXC cards. The 645D features dual card slots, which can be very useful in case a memory card fails. In contrast, the XT only has one slot.

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 Rebel XT 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.		Canon XT	Y	- / -	-	-	-	2.0	-	-	-
2.		Pentax 645D	Y	stereo / -	-	-	-	2.0	-	-	-
3.		Canon 77D	Y	stereo / mono	Y	-	mini	2.0	Y	Y	Y
4.		Canon T6i	Y	stereo / mono	Y	-	mini	2.0	Y	Y	-
5.		Canon T6s	Y	stereo / mono	Y	-	mini	2.0	Y	Y	-
6.		Canon T4i	Y	stereo / mono	Y	-	mini	2.0	-	-	-
7.		Canon 1D X	Y	mono / -	Y	-	mini	2.0	-	-	-
8.		Canon 1D Mark IV	Y	stereo / -	Y	-	mini	2.0	-	-	-
9.		Canon T1i	Y	mono / mono	-	-	mini	2.0	-	-	-
10.		Canon XSi	Y	- / -	-	-	mini	2.0	-	-	-
11.		Canon 30D	Y	- / -	-	-	-	2.0	-	-	-
12.		Canon XTi	Y	- / -	-	-	-	2.0	-	-	-
13.		Canon 20D	Y	- / -	-	-	-	1.1	-	-	-
14.		Canon Rebel	Y	- / -	-	-	-	1.1	-	-	-
15.		Leica S Typ 006	Y	- / -	-	-	mini	2.0	-	-	-
16.		Nikon D3S	Y	stereo / -	-	-	mini	2.0	-	-	-
17.		Pentax 645Z	Y	stereo / mono	Y	-	mini	3.0	-	-	-

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

Both the XT and the 645D have been discontinued, but can regularly be found used on ebay. The XT was replaced by the Canon Xti, while the 645D was followed by the Pentax 645Z. Further information on the features and operation of the XT and 645D can be found, respectively, in the Canon XT Manual (free pdf) or the online Pentax 645D Manual.

Review summary

So what conclusions can be drawn? Which of the two cameras – the Canon XT or the Pentax 645D – has the upper hand? Is one clearly better than the other? The listing below highlights the relative strengths of the two models.

Reasons to prefer the Canon EOS Rebel XT:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Faster burst: Shoots at higher frequency (3 vs 1.1 flaps/sec) to capture the decisive moment.
• More compact: Is smaller (127x94mm vs 156x117mm) and thus needs less room in the bag.
• Less heavy: Is lighter (by 940g or 64 percent) and hence easier to carry around.
• Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
• More affordable: Was introduced into a lower priced category (91 percent cheaper at launch).
• More heavily discounted: Has been available for much longer (launched in February 2005).

Advantages of the Pentax 645D:

• More detail: Has more megapixels (39.5 vs 8MP), which boosts linear resolution by 118%.
• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• Better image quality: Scores substantially higher (22 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (2.8 bits more color depth).
• More dynamic range: Captures a broader range of light and dark details (1.8 EV of extra DR).
• Better low-light sensitivity: Can shoot in dim conditions (1 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 0.49x).
• Easier setting verification: Features a control panel on top to check shooting parameters.
• 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 (921k vs 115k dots).
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• Longer lasting: Gets more shots (800 versus 400) out of a single battery charge.
• 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.
• Greater peace of mind: Features a second card slot as a backup in case of memory card failure.
• More modern: Reflects 5 years of technical progress since the XT launch.

If the count of individual advantages (bullet points above) is taken as a guide, the 645D is the clear winner of the contest (17 : 7 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 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 XT 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 XT and the 645D in practical situations. 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 following table reports the overall ratings of the cameras as published by some of the major 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 XT	..	80/100	..	+ +	o	..	Feb 2005	899	ebay.com
2.		Pentax 645D	5/5	..	..	..	..	..	Mar 2010	9,995	ebay.com
3.		Canon 77D	4.5/5	..	4/5	82/100	4.5/5	4/5	Feb 2017	899	ebay.com
4.		Canon T6i	5/5	..	..	75/100	4.5/5	4.5/5	Feb 2015	749	ebay.com
5.		Canon T6s	5/5	+	..	77/100	4.5/5	4.5/5	Feb 2015	649	ebay.com
6.		Canon T4i	4/5	+ +	..	77/100	4.5/5	4.5/5	Jun 2012	849	ebay.com
7.		Canon 1D X	5/5	..	..	..	4.5/5	4.5/5	Oct 2011	6,799	ebay.com
8.		Canon 1D Mark IV	5/5	..	..	89/100	..	..	Oct 2009	4,999	ebay.com
9.		Canon T1i	..	+ +	..	74/100	4.5/5	4.5/5	Mar 2009	799	ebay.com
10.		Canon XSi	..	+ +	..	+ +	4/5	4.5/5	Jan 2008	799	ebay.com
11.		Canon 30D	..	+ +	..	+ +	o	..	Feb 2006	1,399	ebay.com
12.		Canon XTi	..	+ +	..	+ +	o	4/5	Aug 2006	799	ebay.com
13.		Canon 20D	..	..	..	+ +	..	..	Aug 2004	1,499	ebay.com
14.		Canon Rebel	..	..	..	+ +	..	..	Aug 2003	899	ebay.com
15.		Leica S Typ 006	..	..	..	..	..	..	Sep 2012	21,950	ebay.com
16.		Nikon D3S	5/5	..	..	89/100	4.5/5	5/5	Oct 2009	5,199	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 are only valid when referring to cameras in the same category and of the same age. A score, therefore, has to be seen in close connection to the price and market introduction time of the camera, and comparing ratings of very distinct cameras or ones that are far apart in terms of their release date have little meaning. Also, please note that some of the review sites have changed their methodology and reporting over time.

Check XT offers at
ebay.com
Check 645D offers at
ebay.com

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.

~

Check XT offers at
ebay.com
Check 645D offers at
ebay.com

Did you notice an error on this page? If so, please get in touch, so that we can correct the information.