Pentax 645Z vs YI M1

The Pentax 645Z and the YI M1 are two digital cameras that were officially introduced, respectively, in April 2014 and September 2016. The 645Z is a DSLR, while the M1 is a mirrorless interchangeable lens camera. The cameras are based on a medium format (645Z) and a Four Thirds (M1) sensor. The Pentax has a resolution of 51.1 megapixels, whereas the YI provides 20.2 MP.

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

Headline Specifications

Pentax 645Z		YI M1
Digital single lens reflex		Mirrorless system camera
Pentax 645 mount lenses		Micro Four Thirds lenses
51.1 MP – Medium Format sensor		20.2 MP – Four Thirds sensor
1080/60i Video		4K/30p Video
ISO 100-204,800		ISO 100-25,600
Optical viewfinder		No viewfinder, LCD framing
3.2" LCD – 1037k dots		3.0" LCD – 1040k dots
Tilting screen (no touchscreen)		Fixed touchscreen
3 shutter flaps per second		5 shutter flaps per second
Weathersealed body		not weather sealed
650 shots per battery charge		450 shots per battery charge
156 x 117 x 123 mm, 1550 g		114 x 64 x 34 mm, 281 g

Check 645Z offers at
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Going beyond this snapshot of core features and characteristics, what are the differences between the Pentax 645Z and the YI M1? 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 YI M1 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 width, height and depth measures are rounded to the nearest millimeter.

The M1 can be obtained in two different colors (black, silver), 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 YI M1 is considerably smaller (60 percent) than the Pentax 645Z. Moreover, the M1 is substantially lighter (82 percent) than the 645Z. It is worth mentioning in this context that the 645Z is splash and dust resistant, while the M1 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 M1 can take 450 images on a single charge of its YI BXM-10 power pack. The power pack in the M1 can be charged via the USB port, which can be very convenient when travelling.

The following table provides a synthesis of the main physical specifications of the two cameras and other similar ones. 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.		YI M1	114 mm	64 mm	34 mm	281 g	450	n	Sep 2016	349	ebay.com
3.		Canon SX730	110 mm	64 mm	40 mm	300 g	250	n	Apr 2017	399	ebay.com
4.		Canon 1D X Mark II	158 mm	168 mm	83 mm	1530 g	1210	Y	Feb 2016	5,999	ebay.com
5.		Canon 5DS	152 mm	116 mm	76 mm	930 g	700	Y	Feb 2015	3,699	ebay.com
6.		Canon 5DS R	152 mm	116 mm	76 mm	930 g	700	Y	Feb 2015	3,699	ebay.com
7.		Fujifilm X-A3	117 mm	67 mm	40 mm	339 g	410	n	Aug 2016	399	ebay.com
8.		Hasselblad X1D	150 mm	98 mm	71 mm	725 g	..	Y	Jun 2016	8,995	ebay.com
9.		Leica M11	139 mm	80 mm	39 mm	640 g	700	Y	Jan 2022	8,995	amazon.com
10.		Leica SL	147 mm	104 mm	39 mm	847 g	400	Y	Oct 2015	7,450	ebay.com
11.		Nikon D5	160 mm	159 mm	92 mm	1415 g	3780	Y	Jan 2016	6,499	ebay.com
12.		Nikon D7200	136 mm	107 mm	76 mm	765 g	1110	Y	Mar 2015	1,199	ebay.com
13.		Nikon 1 J5	98 mm	60 mm	32 mm	231 g	250	n	Apr 2015	399	ebay.com
14.		Nikon D4S	160 mm	157 mm	91 mm	1350 g	3020	Y	Feb 2014	6,499	ebay.com
15.		Panasonic GX850	107 mm	65 mm	33 mm	269 g	210	n	Jan 2017	549	ebay.com
16.		Panasonic GF7	107 mm	65 mm	33 mm	266 g	230	n	Jan 2015	499	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

The price is, of course, an important factor in any camera decision. The retail prices at the time of the camera’s release place the model in the market relative to other models in the producer’s line-up and the competition. The M1 was launched at a markedly lower price (by 96 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. 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 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 YI M1 a Four Thirds sensor. The sensor area in the M1 is 84 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 0.79 and 2.0. Both cameras feature a native aspect ratio (sensor width to sensor height) of 4:3.

With 51.1MP, the 645Z offers a higher resolution than the M1 (20.2MP), but the 645Z nevertheless has larger individual pixels (pixel pitch of 5.30μm versus 3.34μm for the M1) due to its larger sensor. However, the M1 is a much more recent model (by 2 years and 5 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 YI M1 are 25.9 x 19.4 inches or 65.8 x 49.4 cm for good quality, 20.7 x 15.6 inches or 52.7 x 39.5 cm for very good quality, and 17.3 x 13 inches or 43.9 x 32.9 cm for excellent quality prints.

The Pentax 645Z has a native sensitivity range from ISO 100 to ISO 204800. The corresponding ISO settings for the YI M1 are ISO 100 to ISO 25600 (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 assesses and scores the color depth ("DXO Portrait"), dynamic range ("DXO Landscape"), and low-light sensitivity ("DXO Sports") of camera sensors, and also publishes an overall camera score. The adjacent table reports on the physical sensor characteristics and the outcomes of the DXO sensor quality tests for a sample of comparator-cameras.

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.		YI M1	Four Thirds	20.2	5184	3888	4K/30p	23.0	12.6	1030	73
3.		Canon SX730	1/2.3	20.2	5184	3888	1080/60p	20.5	11.9	924	50
4.		Canon 1D X Mark II	Full Frame	20.0	5472	3648	4K/60p	24.1	13.5	3207	88
5.		Canon 5DS	Full Frame	50.3	8688	5792	1080/30p	24.7	12.4	2381	87
6.		Canon 5DS R	Full Frame	50.3	8688	5792	1080/30p	24.6	12.4	2308	86
7.		Fujifilm X-A3	APS-C	24.0	6000	4000	1080/60p	23.8	13.1	1664	81
8.		Hasselblad X1D	Medium Format	51.3	8272	6200	1080/25p	26.2	14.8	4489	102
9.		Leica M11	Full Frame	60.3	9528	6328	none	26.3	14.8	3376	100
10.		Leica SL	Full Frame	24.0	6000	4000	4K/30p	25.0	13.4	1821	88
11.		Nikon D5	Full Frame	20.7	5588	3712	4K/30p	25.1	12.3	2343	88
12.		Nikon D7200	APS-C	24.0	6000	4000	1080/60p	24.5	14.6	1333	87
13.		Nikon 1 J5	1-inch	20.7	5568	3712	4K/15p	21.1	12.0	479	65
14.		Nikon D4S	Full Frame	16.2	4928	3280	1080/60p	24.4	13.3	3074	89
15.		Panasonic GX850	Four Thirds	15.8	4592	3448	4K/30p	23.2	13.3	586	73
16.		Panasonic GF7	Four Thirds	15.8	4592	3448	1080/60p	22.7	12.3	874	70
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 have a sensor with sufficiently fast read-out times for moving pictures, but the M1 provides a better video resolution than the 645Z. It can shoot movie footage at 4K/30p, while the Pentax is limited to 1080/60i.

Feature comparison

Apart from body and sensor, cameras can and do differ across a range of features. For example, the 645Z has an optical viewfinder, which can be very useful when shooting in bright sunlight. In contrast, the M1 relies on live view and the rear LCD for framing. The following table reports on some other key feature differences and similarities of the Pentax 645Z, the YI M1, 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.		Pentax 645Z	optical	Y	3.2 / 1037	tilting	n	1/4000s	3.0/s	n	n
2.		YI M1	none	n	3.0 / 1040	fixed	Y	1/4000s	5.0/s	n	n
3.		Canon SX730	none	n	3.0 / 922	tilting	n	1/3200s	5.9/s	Y	Y
4.		Canon 1D X Mark II	optical	Y	3.2 / 1620	fixed	Y	1/8000s	16.0/s	n	n
5.		Canon 5DS	optical	Y	3.2 / 1040	fixed	n	1/8000s	5.0/s	n	n
6.		Canon 5DS R	optical	Y	3.2 / 1040	fixed	n	1/8000s	5.0/s	n	n
7.		Fujifilm X-A3	none	n	3.0 / 1040	tilting	Y	1/4000s	6.0/s	Y	n
8.		Hasselblad X1D	2360	n	3.0 / 920	fixed	Y	1/2000s	2.3/s	n	n
9.		Leica M11	optical	n	3.0 / 2333	fixed	Y	1/4000s	4.5/s	n	n
10.		Leica SL	4400	Y	3.0 / 1040	fixed	Y	1/8000s	11.0/s	n	n
11.		Nikon D5	optical	Y	3.2 / 2359	fixed	Y	1/8000s	14.0/s	n	n
12.		Nikon D7200	optical	Y	3.2 / 1229	fixed	n	1/8000s	6.0/s	Y	n
13.		Nikon 1 J5	none	n	3.0 / 1037	tilting	Y	1/4000s	60.0/s	Y	n
14.		Nikon D4S	optical	Y	3.2 / 921	fixed	n	1/8000s	11.0/s	n	n
15.		Panasonic GX850	none	n	3.0 / 1040	tilting	Y	1/500s	10.0/s	Y	n
16.		Panasonic GF7	none	n	3.0 / 1040	tilting	Y	1/500s	5.8/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 M1 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 YI M1 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 M1 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 M1 only has one slot. The 645Z supports UHS-I cards (Ultra High Speed data transfer of up to 104 MB/s), while the M1 cannot take advantage of Ultra High Speed SD 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 Pentax 645Z and YI M1 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.		YI M1	Y	stereo / mono	-	-	micro	2.0	Y	-	Y
3.		Canon SX730	-	stereo / mono	-	-	micro	2.0	Y	Y	Y
4.		Canon 1D X Mark II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
5.		Canon 5DS	Y	mono / mono	Y	-	mini	3.0	-	-	-
6.		Canon 5DS R	Y	mono / mono	Y	-	mini	3.0	-	-	-
7.		Fujifilm X-A3	Y	stereo / mono	-	-	micro	2.0	Y	-	-
8.		Hasselblad X1D	Y	stereo / mono	Y	Y	mini	3.0	Y	-	-
9.		Leica M11	Y	- / -	-	-	-	3.2	Y	-	Y
10.		Leica SL	Y	stereo / mono	Y	Y	full	3.0	Y	-	-
11.		Nikon D5	Y	stereo / mono	Y	Y	mini	3.0	-	-	-
12.		Nikon D7200	Y	stereo / mono	Y	Y	mini	2.0	Y	Y	-
13.		Nikon 1 J5	-	stereo / mono	-	-	micro	2.0	Y	Y	-
14.		Nikon D4S	Y	mono / mono	Y	Y	mini	2.0	-	-	-
15.		Panasonic GX850	-	stereo / mono	-	-	micro	2.0	Y	-	-
16.		Panasonic GF7	-	stereo / mono	-	-	micro	2.0	Y	Y	-
17.		Pentax 645D	Y	stereo / -	-	-	-	2.0	-	-	-

It is notable that the 645Z has a microphone port, which is missing on the M1. Such an external microphone input can help to substantially improve the quality of audio recordings when a good external microphone is used.

Studio photographers will appreciate that the Pentax 645Z (unlike the M1) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the 645Z and the M1 have been discontinued, but can regularly be found used on ebay. Neither of the two has a direct successor, so they represent the end of the respective camera lines from Pentax and YI. Further information on the features and operation of the 645Z and M1 can be found, respectively, in the Pentax 645Z Manual (free pdf) or the online YI M1 Manual.

Review summary

So what conclusions can be drawn? Is there a clear favorite between the Pentax 645Z and the YI M1? Which camera is better? A synthesis of the relative strong points of each of the models is listed below.

Reasons to prefer the Pentax 645Z:

• More detail: Offers more megapixels (51.1 vs 20.2MP) with a 59% higher linear resolution.
• Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
• Better image quality: Features bigger pixels on a larger sensor for higher quality imaging.
• Richer colors: The pixel size advantage translates into images with better, more accurate colors.
• More dynamic range: Larger pixels capture a wider spectrum of light and dark details.
• Better low-light sensitivity: Larger pixels means good image quality even under poor lighting.
• Better sound: Can connect to an external microphone for higher quality sound recording.
• 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.
• Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
• More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
• Longer lasting: Can take more shots (650 versus 450) on a single battery charge.
• 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.
• Faster buffer clearing: Has an SD card interface that supports the UHS-I standard.
• More heavily discounted: Has been available for much longer (launched in April 2014).

Arguments in favor of the YI M1:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Better video: Provides higher definition movie capture (4K/30p vs 1080/60i).
• Fewer buttons to press: Has a touchscreen to facilitate handling and shooting adjustments.
• Faster burst: Shoots at higher frequency (5 vs 3 flaps/sec) to capture the decisive moment.
• More compact: Is smaller (114x64mm vs 156x117mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 1269g or 82 percent) and is thus easier to take along.
• Easier travel charging: Can be conveniently charged via its USB port.
• 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 wireless transfer: Supports Bluetooth for image sharing without cables.
• More affordable: Was introduced into a lower priced category (96 percent cheaper at launch).
• More modern: Reflects 2 years and 5 months of technical progress since the 645Z launch.

If the count of individual advantages (bullet points above) is taken as a guide, the 645Z is the clear winner of the match-up (18 : 12 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 Pentax 645Z and the YI M1 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 incomplete and does no justice, for example, to the way the 645Z or the M1 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 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.		Pentax 645Z	5/5	..	3.5/5	..	4.5/5	5/5	Apr 2014	8,499	ebay.com
2.		YI M1	..	..	..	69/100	..	..	Sep 2016	349	ebay.com
3.		Canon SX730	..	+	..	..	4/5	4/5	Apr 2017	399	ebay.com
4.		Canon 1D X Mark II	..	..	4.5/5	89/100	4.5/5	4.5/5	Feb 2016	5,999	ebay.com
5.		Canon 5DS	..	+	..	83/100	4.5/5	4.5/5	Feb 2015	3,699	ebay.com
6.		Canon 5DS R	5/5	+	..	83/100	5/5	4.5/5	Feb 2015	3,699	ebay.com
7.		Fujifilm X-A3	..	..	..	74/100	4.5/5	4/5	Aug 2016	399	ebay.com
8.		Hasselblad X1D	..	o	..	81/100	..	4/5	Jun 2016	8,995	ebay.com
9.		Leica M11	4.5/5	..	4.5/5	..	4.5/5	4.5/5	Jan 2022	8,995	amazon.com
10.		Leica SL	4/5	..	4/5	84/100	4.5/5	4/5	Oct 2015	7,450	ebay.com
11.		Nikon D5	..	..	4/5	89/100	4.5/5	5/5	Jan 2016	6,499	ebay.com
12.		Nikon D7200	4/5	+ +	..	84/100	4.5/5	4.5/5	Mar 2015	1,199	ebay.com
13.		Nikon 1 J5	..	..	..	..	4.5/5	4.5/5	Apr 2015	399	ebay.com
14.		Nikon D4S	5/5	..	..	..	4.5/5	4.5/5	Feb 2014	6,499	ebay.com
15.		Panasonic GX850	..	+	..	76/100	4.5/5	4.5/5	Jan 2017	549	ebay.com
16.		Panasonic GF7	4/5	+	..	..	4.5/5	4.5/5	Jan 2015	499	ebay.com
17.		Pentax 645D	5/5	..	..	..	..	..	Mar 2010	9,995	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 comparisons of ratings among very different cameras or across long time periods have little meaning. Also, kindly note that some of the listed sites have over time developped their review approaches and their reporting style.

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Other camera comparisons

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