Pentax 645Z vs Canon SL3

The Pentax 645Z and the Canon EOS Rebel SL3 (labelled Canon 250D in some countries) are two digital cameras that were announced, respectively, in April 2014 and April 2019. Both are DSLR (Digital Single Lens Reflex) cameras that are based on a medium format (645Z) and an APS-C (SL3) sensor. The Pentax has a resolution of 51.1 megapixels, whereas the Canon provides 24 MP.

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

Headline Specifications

Pentax 645Z		Canon SL3
Digital single lens reflex		Digital single lens reflex
Pentax 645 mount lenses		Canon EF mount lenses
51.1 MP – Medium Format sensor		24 MP – APS-C sensor
1080/60i Video		4K/25p Video
ISO 100-204,800		ISO 100-25,600 (100 - 51,200)
Optical viewfinder		Optical viewfinder
3.2" LCD – 1037k dots		3.0" LCD – 1040k dots
Tilting screen (no touchscreen)		Swivel touchscreen
3 shutter flaps per second		5 shutter flaps per second
Weathersealed body		not weather sealed
650 shots per battery charge		1070 shots per battery charge
156 x 117 x 123 mm, 1550 g		122 x 93 x 70 mm, 449 g

Check 645Z offers at
ebay.com
Check SL3 price at
amazon.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Pentax 645Z and the Canon EOS Rebel SL3? 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 Pentax 645Z and the Canon SL3 is provided in the side-by-side display below. The two cameras are presented according to their relative size. Three successive views from the front, the top, and the rear are shown. All width, height and depth measures are rounded to the nearest millimeter.

The SL3 can be obtained in two different colors (black, white), while the 645Z 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 SL3 is considerably smaller (38 percent) than the Pentax 645Z. Moreover, the SL3 is substantially lighter (71 percent) than the 645Z. It is worth mentioning in this context that the 645Z is splash and dust resistant, while the SL3 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 645Z gets 650 shots out of its Pentax D-LI90 battery, while the SL3 can take 1070 images on a single charge of its Canon LP-E17 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 (USD)	Street Price
1.		Pentax 645Z	156 mm	117 mm	123 mm	1550 g	650	Y	Apr 2014	8,499	ebay.com
2.		Canon SL3	122 mm	93 mm	70 mm	449 g	1070	n	Apr 2019	599	amazon.com
3.		Canon 1D X Mark II	158 mm	168 mm	83 mm	1530 g	1210	Y	Feb 2016	5,999	ebay.com
4.		Canon 5DS	152 mm	116 mm	76 mm	930 g	700	Y	Feb 2015	3,699	ebay.com
5.		Canon 5DS R	152 mm	116 mm	76 mm	930 g	700	Y	Feb 2015	3,699	ebay.com
6.		Canon 77D	131 mm	100 mm	76 mm	540 g	600	n	Feb 2017	899	ebay.com
7.		Canon M50 Mark II	116 mm	88 mm	59 mm	387 g	305	n	Oct 2020	599	ebay.com
8.		Canon SL2	122 mm	93 mm	70 mm	453 g	650	n	Jun 2017	549	ebay.com
9.		Canon T7	129 mm	101 mm	78 mm	475 g	500	n	Feb 2018	449	amazon.com
10.		Canon T8i	131 mm	103 mm	76 mm	515 g	800	n	Feb 2020	749	ebay.com
11.		Hasselblad X1D	150 mm	98 mm	71 mm	725 g	..	Y	Jun 2016	8,995	ebay.com
12.		Leica M11	139 mm	80 mm	39 mm	640 g	700	Y	Jan 2022	8,995	amazon.com
13.		Leica SL	147 mm	104 mm	39 mm	847 g	400	Y	Oct 2015	7,450	ebay.com
14.		Nikon D4S	160 mm	157 mm	91 mm	1350 g	3020	Y	Feb 2014	6,499	ebay.com
15.		Nikon D5	160 mm	159 mm	92 mm	1415 g	3780	Y	Jan 2016	6,499	ebay.com
16.		Nikon D7200	136 mm	107 mm	76 mm	765 g	1110	Y	Mar 2015	1,199	ebay.com
17.		Pentax 645D	156 mm	117 mm	119 mm	1480 g	800	Y	Mar 2010	9,995	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 listed launch prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The SL3 was launched at a markedly lower price (by 93 percent) than the 645Z, 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 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. 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 tend to be associated with larger, more expensive camera bodies and lenses.

Of the two cameras under consideration, the Pentax 645Z features a medium format sensor and the Canon SL3 an APS-C sensor. The sensor area in the SL3 is 77 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 0.79 and 1.6. The sensor in the 645Z has a native 4:3 aspect ratio, while the one in the SL3 offers a 3:2 aspect.

With 51.1MP, the 645Z offers a higher resolution than the SL3 (24MP), but the 645Z nevertheless has larger individual pixels (pixel pitch of 5.30μm versus 3.72μm for the SL3) due to its larger sensor. However, the SL3 is a much more recent model (by 4 years and 11 months) than the 645Z, and its sensor will have benefitted from technological advances during this time that further enhance the light gathering capacity of its pixels. Coming back to sensor resolution, it should be mentioned that the 645Z has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

The resolution advantage of the Pentax 645Z implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the 645Z for good quality output (200 dots per inch) amounts to 41.3 x 31 inches or 104.9 x 78.6 cm, for very good quality (250 dpi) 33 x 24.8 inches or 83.9 x 62.9 cm, and for excellent quality (300 dpi) 27.5 x 20.6 inches or 69.9 x 52.4 cm. The corresponding values for the Canon SL3 are 30 x 20 inches or 76.2 x 50.8 cm for good quality, 24 x 16 inches or 61 x 40.6 cm for very good quality, and 20 x 13.3 inches or 50.8 x 33.9 cm for excellent quality prints.

The SL3 has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

The Pentax 645Z has a native sensitivity range from ISO 100 to ISO 204800. The corresponding ISO settings for the Canon EOS Rebel SL3 are ISO 100 to ISO 25600, with the possibility to increase the ISO range to 100-51200.

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 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"). 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.		Pentax 645Z	Medium Format	51.1	8256	6192	1080/60i	26.0	14.7	4505	101
2.		Canon SL3	APS-C	24.0	6000	4000	4K/25p	23.9	13.4	1791	82
3.		Canon 1D X Mark II	Full Frame	20.0	5472	3648	4K/60p	24.1	13.5	3207	88
4.		Canon 5DS	Full Frame	50.3	8688	5792	1080/30p	24.7	12.4	2381	87
5.		Canon 5DS R	Full Frame	50.3	8688	5792	1080/30p	24.6	12.4	2308	86
6.		Canon 77D	APS-C	24.0	6000	4000	1080/60p	23.6	13.3	971	78
7.		Canon M50 Mark II	APS-C	24.0	6000	4000	4K/24p	24.0	13.6	1939	83
8.		Canon SL2	APS-C	24.0	6000	4000	1080/60p	23.6	13.4	1041	79
9.		Canon T7	APS-C	24.0	6000	4000	1080/30p	23.8	13.3	1684	81
10.		Canon T8i	APS-C	24.0	6000	4000	4K/24p	24.0	13.5	1873	83
11.		Hasselblad X1D	Medium Format	51.3	8272	6200	1080/25p	26.2	14.8	4489	102
12.		Leica M11	Full Frame	60.3	9528	6328	none	26.3	14.8	3376	100
13.		Leica SL	Full Frame	24.0	6000	4000	4K/30p	25.0	13.4	1821	88
14.		Nikon D4S	Full Frame	16.2	4928	3280	1080/60p	24.4	13.3	3074	89
15.		Nikon D5	Full Frame	20.7	5588	3712	4K/30p	25.1	12.3	2343	88
16.		Nikon D7200	APS-C	24.0	6000	4000	1080/60p	24.5	14.6	1333	87
17.		Pentax 645D	Medium Format	39.5	7264	5440	none	24.6	12.6	1262	82
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. Both cameras under consideration are equipped with sensors that have a sufficiently high read-out speed for moving images, but the SL3 provides a better video resolution than the 645Z. It can shoot movie footage at 4K/25p, while the Pentax is limited to 1080/60i.

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. The 645Z and the SL3 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 645Z offers a wider field of view (98%) than the one in the SL3 (95%), so that a larger proportion of the captured image is visible in the finder. In addition, the viewfinder of the 645Z has a higher magnification (0.78x vs 0.54x), 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 Pentax 645Z and Canon SL3 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.		Pentax 645Z	optical	Y	3.2 / 1037	tilting	n	1/4000s	3.0/s	n	n
2.		Canon SL3	optical	n	3.0 / 1040	swivel	Y	1/4000s	5.0/s	Y	n
3.		Canon 1D X Mark II	optical	Y	3.2 / 1620	fixed	Y	1/8000s	16.0/s	n	n
4.		Canon 5DS	optical	Y	3.2 / 1040	fixed	n	1/8000s	5.0/s	n	n
5.		Canon 5DS R	optical	Y	3.2 / 1040	fixed	n	1/8000s	5.0/s	n	n
6.		Canon 77D	optical	Y	3.0 / 1040	swivel	Y	1/4000s	6.0/s	Y	n
7.		Canon M50 Mark II	2360	n	3.0 / 1040	swivel	Y	1/4000s	10.0/s	Y	n
8.		Canon SL2	optical	n	3.0 / 1040	swivel	Y	1/4000s	5.0/s	Y	n
9.		Canon T7	optical	n	3.0 / 920	fixed	n	1/4000s	3.0/s	Y	n
10.		Canon T8i	optical	n	3.0 / 1040	swivel	Y	1/4000s	7.5/s	Y	n
11.		Hasselblad X1D	2360	n	3.0 / 920	fixed	Y	1/2000s	2.3/s	n	n
12.		Leica M11	optical	n	3.0 / 2333	fixed	Y	1/4000s	4.5/s	n	n
13.		Leica SL	4400	Y	3.0 / 1040	fixed	Y	1/8000s	11.0/s	n	n
14.		Nikon D4S	optical	Y	3.2 / 921	fixed	n	1/8000s	11.0/s	n	n
15.		Nikon D5	optical	Y	3.2 / 2359	fixed	Y	1/8000s	14.0/s	n	n
16.		Nikon D7200	optical	Y	3.2 / 1229	fixed	n	1/8000s	6.0/s	Y	n
17.		Pentax 645D	optical	Y	3.0 / 921	fixed	n	1/4000s	1.1/s	n	n
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that is present on the 645Z, but is missing on the SL3 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 Pentax 645Z and the Canon SL3 both have 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.

Concerning the storage of imaging data, both the 645Z and the SL3 write their files to SDXC cards. The 645Z features dual card slots, which can be very useful in case a memory card fails. In contrast, the SL3 only has one slot. Both cameras can use UHS-I cards, which provide for Ultra High Speed data transfer of up to 104 MB/s.

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 Pentax 645Z and Canon EOS Rebel SL3 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.		Pentax 645Z	Y	stereo / mono	Y	-	mini	3.0	-	-	-
2.		Canon SL3	Y	stereo / mono	Y	-	mini	2.0	Y	-	Y
3.		Canon 1D X Mark II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
4.		Canon 5DS	Y	mono / mono	Y	-	mini	3.0	-	-	-
5.		Canon 5DS R	Y	mono / mono	Y	-	mini	3.0	-	-	-
6.		Canon 77D	Y	stereo / mono	Y	-	mini	2.0	Y	Y	Y
7.		Canon M50 Mark II	Y	stereo / mono	Y	-	micro	2.0	Y	-	Y
8.		Canon SL2	Y	stereo / mono	Y	-	mini	2.0	Y	Y	Y
9.		Canon T7	Y	mono / mono	-	-	mini	2.0	Y	Y	-
10.		Canon T8i	Y	stereo / mono	Y	-	mini	2.0	Y	-	Y
11.		Hasselblad X1D	Y	stereo / mono	Y	Y	mini	3.0	Y	-	-
12.		Leica M11	Y	- / -	-	-	-	3.2	Y	-	Y
13.		Leica SL	Y	stereo / mono	Y	Y	full	3.0	Y	-	-
14.		Nikon D4S	Y	mono / mono	Y	Y	mini	2.0	-	-	-
15.		Nikon D5	Y	stereo / mono	Y	Y	mini	3.0	-	-	-
16.		Nikon D7200	Y	stereo / mono	Y	Y	mini	2.0	Y	Y	-
17.		Pentax 645D	Y	stereo / -	-	-	-	2.0	-	-	-

It is notable that the SL3 offers wifi support, which can be a very convenient means to transfer image data to an off-camera location. In contrast, the 645Z does not provide wifi capability.

Studio photographers will appreciate that the Pentax 645Z (unlike the SL3) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

The SL3 is a recent model that features in the current product line-up of Canon. In contrast, the 645Z has been discontinued (but can be found pre-owned on ebay). There has not been a direct replacement model for the 645Z from Pentax. Further information on the features and operation of the 645Z and SL3 can be found, respectively, in the Pentax 645Z Manual (free pdf) or the online Canon SL3 Manual.

Review summary

So what conclusions can be drawn? Is the Pentax 645Z better than the Canon SL3 or vice versa? A synthesis of the relative strong points of each of the models is listed below.

Advantages of the Pentax 645Z:

• More detail: Offers more megapixels (51.1 vs 24MP) with a 43% higher linear resolution.
• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• 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 0.54x).
• Easier setting verification: Features an LCD display on top to control shooting parameters.
• Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
• Better sealing: Is weather sealed to enable shooting in dusty or wet environments.
• Faster data transfer: Supports a more advanced USB protocol (3.0 vs 2.0).
• 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 heavily discounted: Has been available for much longer (launched in April 2014).

Reasons to prefer the Canon EOS Rebel SL3:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Better video: Provides higher definition movie capture (4K/25p vs 1080/60i).
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• More flexible LCD: Has a swivel screen for odd-angle shots in portrait or 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.
• Faster burst: Shoots at higher frequency (5 vs 3 flaps/sec) to capture the decisive moment.
• More compact: Is smaller (122x93mm vs 156x117mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 1101g or 71 percent) and is thus easier to take along.
• Longer lasting: Gets more shots (1070 versus 650) out of a single battery charge.
• Easier fill-in: Has a small integrated flash to brighten shadows of backlit subjects.
• Easier file upload: Has wifi built in for automatic backup or image transfer to the web.
• Easier wireless transfer: Supports Bluetooth for image sharing without cables.
• More affordable: Was introduced into a lower priced category (93 percent cheaper at launch).
• More modern: Reflects 4 years and 11 months of technical progress since the 645Z launch.

If the count of relative strengths (bullet points above) is taken as a measure, the SL3 is the clear winner of the contest (15 : 11 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 Pentax 645Z and the Canon SL3 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 remains partial and cannot reveal, for example, the shooting experience and imaging performance when actually working with the 645Z or the SL3. 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 expert reviews are important. 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.		Pentax 645Z	5/5	..	3.5/5	..	4.5/5	5/5	Apr 2014	8,499	ebay.com
2.		Canon SL3	4/5	o	4.5/5	79/100	4/5	4/5	Apr 2019	599	amazon.com
3.		Canon 1D X Mark II	..	..	4.5/5	89/100	4.5/5	4.5/5	Feb 2016	5,999	ebay.com
4.		Canon 5DS	..	+	..	83/100	4.5/5	4.5/5	Feb 2015	3,699	ebay.com
5.		Canon 5DS R	5/5	+	..	83/100	5/5	4.5/5	Feb 2015	3,699	ebay.com
6.		Canon 77D	4.5/5	..	4/5	82/100	4.5/5	4/5	Feb 2017	899	ebay.com
7.		Canon M50 Mark II	4/5	..	4/5	..	4.5/5	3.5/5	Oct 2020	599	ebay.com
8.		Canon SL2	4/5	+ +	4/5	78/100	4.5/5	4.5/5	Jun 2017	549	ebay.com
9.		Canon T7	..	o	3.5/5	..	3.5/5	3.5/5	Feb 2018	449	amazon.com
10.		Canon T8i	4.5/5	+	3/5	80/100	4/5	3.5/5	Feb 2020	749	ebay.com
11.		Hasselblad X1D	..	o	..	81/100	..	4/5	Jun 2016	8,995	ebay.com
12.		Leica M11	4.5/5	..	4.5/5	..	4.5/5	4.5/5	Jan 2022	8,995	amazon.com
13.		Leica SL	4/5	..	4/5	84/100	4.5/5	4/5	Oct 2015	7,450	ebay.com
14.		Nikon D4S	5/5	..	..	..	4.5/5	4.5/5	Feb 2014	6,499	ebay.com
15.		Nikon D5	..	..	4/5	89/100	4.5/5	5/5	Jan 2016	6,499	ebay.com
16.		Nikon D7200	4/5	+ +	..	84/100	4.5/5	4.5/5	Mar 2015	1,199	ebay.com
17.		Pentax 645D	5/5	..	..	..	..	..	Mar 2010	9,995	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The above review scores should be interpreted with care, though. The assessments were made in relation to similar cameras of the same technological generation. Thus, a score needs to be put into the context of the launch date and the launch price 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.

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amazon.com

Other camera comparisons

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