Sony A99 II vs YI M1

The Sony Alpha ALT-A99 II and the YI M1 are two digital cameras that were revealed to the public in September 2016. The A99 II is a DSLR, while the M1 is a mirrorless interchangeable lens camera. The cameras are based on a full frame (A99 II) and a Four Thirds (M1) sensor. The Sony has a resolution of 42.2 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

Sony A99 II		YI M1
Digital single lens reflex		Mirrorless system camera
Sony A mount lenses		Micro Four Thirds lenses
42.2 MP – Full Frame sensor		20.2 MP – Four Thirds sensor
4K/30p Video		4K/30p Video
ISO 100-25,600		ISO 100-25,600
Electronic viewfinder (2400k dots)		No viewfinder, LCD framing
3.0" LCD – 1229k dots		3.0" LCD – 1040k dots
Fully flexible screen (no touchscreen)		Fixed touchscreen
12 shutter flaps per second		5 shutter flaps per second
In-body stabilization		Lens stabilization only
Weathersealed body		not weather sealed
490 shots per battery charge		450 shots per battery charge
143 x 104 x 76 mm, 849 g		114 x 64 x 34 mm, 281 g

Check A99 II offers at
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Check M1 offers at
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Going beyond this snapshot of core features and characteristics, what are the differences between the Sony Alpha ALT-A99 II 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 Sony A99 II 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 views from the front, the top, and the rear side are shown. 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 A99 II 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 (51 percent) than the Sony A99 II. Moreover, the M1 is substantially lighter (67 percent) than the A99 II. It is worth mentioning in this context that the A99 II 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 A99 II gets 490 shots out of its Sony NP-FM500H 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. In case you want to display and compare another camera duo, you can use the CAM-parator app to select your camera combination among a large number of options.

Body Specifications

		Camera Model	Camera Width	Camera Height	Camera Depth	Camera Weight	Battery Life	Weather Sealing	Camera Launch	Launch Price (USD)	Street Price
1.		Sony A99 II	143 mm	104 mm	76 mm	849 g	490	Y	Sep 2016	3,199	ebay.com
2.		YI M1	114 mm	64 mm	34 mm	281 g	450	n	Sep 2016	349	ebay.com
3.		Canon 5DS R	152 mm	116 mm	76 mm	930 g	700	Y	Feb 2015	3,699	ebay.com
4.		Canon SX730	110 mm	64 mm	40 mm	300 g	250	n	Apr 2017	399	ebay.com
5.		Fujifilm X-A3	117 mm	67 mm	40 mm	339 g	410	n	Aug 2016	399	ebay.com
6.		Nikon 1 J5	98 mm	60 mm	32 mm	231 g	250	n	Apr 2015	399	ebay.com
7.		Nikon D850	146 mm	124 mm	79 mm	1005 g	1840	Y	Jul 2017	3,299	amazon.com
8.		Panasonic GF7	107 mm	65 mm	33 mm	266 g	230	n	Jan 2015	499	ebay.com
9.		Panasonic GX850	107 mm	65 mm	33 mm	269 g	210	n	Jan 2017	549	ebay.com
10.		Pentax K-1	137 mm	110 mm	86 mm	1010 g	760	Y	Feb 2016	1,799	ebay.com
11.		Sony A7R II	127 mm	96 mm	60 mm	625 g	290	Y	Jun 2015	3,199	ebay.com
12.		Sony A7R III	127 mm	96 mm	74 mm	650 g	650	Y	Oct 2017	3,199	ebay.com
13.		Sony A7R IIIA	127 mm	96 mm	74 mm	650 g	650	Y	Apr 2021	3,199	amazon.com
14.		Sony A7S II	127 mm	96 mm	60 mm	627 g	370	Y	Sep 2015	2,999	ebay.com
15.		Sony A99	147 mm	111 mm	78 mm	812 g	500	Y	Sep 2012	2,799	ebay.com
16.		Sony A850	156 mm	117 mm	82 mm	895 g	880	Y	Aug 2009	1,999	ebay.com
17.		Sony A900	156 mm	117 mm	82 mm	895 g	880	Y	Sep 2008	2,999	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 M1 was launched at a markedly lower price (by 89 percent) than the A99 II, 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 are more costly to manufacture and tend to lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Sony A99 II features a full frame sensor and the YI M1 a Four Thirds sensor. The sensor area in the M1 is 74 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.0 and 2.0. The sensor in the A99 II has a native 3:2 aspect ratio, while the one in the M1 offers a 4:3 aspect.

With 42.2MP, the A99 II offers a higher resolution than the M1 (20.2MP), but the A99 II nevertheless has larger individual pixels (pixel pitch of 4.52μm versus 3.34μm for the M1) due to its larger sensor. It is noteworthy in this context that the two cameras were released in close succession, so that their sensors are from the same technological generation. Coming back to sensor resolution, it should be mentioned that the A99 II has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

The resolution advantage of the Sony A99 II implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A99 II for good quality output (200 dots per inch) amounts to 39.8 x 26.5 inches or 101 x 67.4 cm, for very good quality (250 dpi) 31.8 x 21.2 inches or 80.8 x 53.9 cm, and for excellent quality (300 dpi) 26.5 x 17.7 inches or 67.3 x 44.9 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 A99 II has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

The Sony Alpha ALT-A99 II has a native sensitivity range from ISO 100 to ISO 25600, which can be extended to ISO 50-25600. The corresponding ISO settings for the YI M1 are ISO 100 to ISO 25600 (no boost).

In terms of underlying technology, the A99 II is build around a BSI-CMOS sensor, while the M1 uses a CMOS 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.

Since 2007, DXO Mark has published sensor performance measurements that have been derived using a consistent methodology. 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 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.		Sony A99 II	Full Frame	42.2	7952	5304	4K/30p	25.4	13.4	2317	92
2.		YI M1	Four Thirds	20.2	5184	3888	4K/30p	23.0	12.6	1030	73
3.		Canon 5DS R	Full Frame	50.3	8688	5792	1080/30p	24.6	12.4	2308	86
4.		Canon SX730	1/2.3	20.2	5184	3888	1080/60p	20.5	11.9	924	50
5.		Fujifilm X-A3	APS-C	24.0	6000	4000	1080/60p	23.8	13.1	1664	81
6.		Nikon 1 J5	1-inch	20.7	5568	3712	4K/15p	21.1	12.0	479	65
7.		Nikon D850	Full Frame	45.4	8256	5504	4K/30p	26.4	14.8	2660	100
8.		Panasonic GF7	Four Thirds	15.8	4592	3448	1080/60p	22.7	12.3	874	70
9.		Panasonic GX850	Four Thirds	15.8	4592	3448	4K/30p	23.2	13.3	586	73
10.		Pentax K-1	Full Frame	36.2	7360	4912	1080/60i	25.4	14.6	3280	96
11.		Sony A7R II	Full Frame	42.2	7952	5304	4K/30p	26.0	13.9	3434	98
12.		Sony A7R III	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
13.		Sony A7R IIIA	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
14.		Sony A7S II	Full Frame	12.0	4240	2832	4K/30p	23.6	13.3	2993	85
15.		Sony A99	Full Frame	24.0	6000	4000	1080/60p	25.0	14.0	1555	89
16.		Sony A850	Full Frame	24.4	6048	4032	none	23.8	12.2	1415	79
17.		Sony A900	Full Frame	24.4	6048	4032	none	23.7	12.3	1431	79
Note: DXO values in italics represent estimates based on sensor size and age.

Many modern cameras are not only capable of taking still images, but also of capturing video footage. Both cameras under consideration are equipped with sensors that have a sufficiently high read-out speed for moving images, and both provide the same movie specifications (4K/30p).

Feature comparison

Apart from body and sensor, cameras can and do differ across a range of features. For example, the A99 II has an electronic viewfinder (2400k dots), which can be very helpful when shooting in bright sunlight. In contrast, the M1 relies on live view and the rear LCD for framing. The table below summarizes some of the other core capabilities of the Sony A99 II and YI M1 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.		Sony A99 II	2400	Y	3.0 / 1229	full-flex	n	1/8000s	12.0/s	n	Y
2.		YI M1	none	n	3.0 / 1040	fixed	Y	1/4000s	5.0/s	n	n
3.		Canon 5DS R	optical	Y	3.2 / 1040	fixed	n	1/8000s	5.0/s	n	n
4.		Canon SX730	none	n	3.0 / 922	tilting	n	1/3200s	5.9/s	Y	Y
5.		Fujifilm X-A3	none	n	3.0 / 1040	tilting	Y	1/4000s	6.0/s	Y	n
6.		Nikon 1 J5	none	n	3.0 / 1037	tilting	Y	1/4000s	60.0/s	Y	n
7.		Nikon D850	optical	Y	3.2 / 2359	tilting	Y	1/8000s	9.0/s	n	n
8.		Panasonic GF7	none	n	3.0 / 1040	tilting	Y	1/500s	5.8/s	Y	n
9.		Panasonic GX850	none	n	3.0 / 1040	tilting	Y	1/500s	10.0/s	Y	n
10.		Pentax K-1	optical	Y	3.2 / 1037	full-flex	n	1/8000s	4.4/s	n	Y
11.		Sony A7R II	2400	n	3.0 / 1229	tilting	n	1/8000s	5.0/s	n	Y
12.		Sony A7R III	3686	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
13.		Sony A7R IIIA	3686	n	3.0 / 2340	tilting	Y	1/8000s	10.0/s	n	Y
14.		Sony A7S II	2400	n	3.0 / 1229	tilting	n	1/8000s	5.0/s	n	Y
15.		Sony A99	2359	Y	3.0 / 1229	full-flex	n	1/8000s	6.0/s	n	Y
16.		Sony A850	optical	Y	3.0 / 922	fixed	n	1/8000s	3.0/s	n	Y
17.		Sony A900	optical	Y	3.0 / 922	fixed	n	1/8000s	5.0/s	n	Y
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that is present on the A99 II, 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 YI M1 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 A99 II writes its imaging data to SDXC or Memory Stick PRO Duo cards, while the M1 uses SDXC cards. The A99 II features dual card slots, which can be very useful in case a memory card fails. In contrast, the M1 only has one slot. The A99 II 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 Sony Alpha ALT-A99 II 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.		Sony A99 II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	Y
2.		YI M1	Y	stereo / mono	-	-	micro	2.0	Y	-	Y
3.		Canon 5DS R	Y	mono / mono	Y	-	mini	3.0	-	-	-
4.		Canon SX730	-	stereo / mono	-	-	micro	2.0	Y	Y	Y
5.		Fujifilm X-A3	Y	stereo / mono	-	-	micro	2.0	Y	-	-
6.		Nikon 1 J5	-	stereo / mono	-	-	micro	2.0	Y	Y	-
7.		Nikon D850	Y	stereo / mono	Y	Y	mini	3.0	Y	Y	Y
8.		Panasonic GF7	-	stereo / mono	-	-	micro	2.0	Y	Y	-
9.		Panasonic GX850	-	stereo / mono	-	-	micro	2.0	Y	-	-
10.		Pentax K-1	Y	stereo / mono	Y	Y	micro	2.0	Y	-	-
11.		Sony A7R II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
12.		Sony A7R III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
13.		Sony A7R IIIA	Y	stereo / mono	Y	Y	micro	3.2	Y	Y	Y
14.		Sony A7S II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
15.		Sony A99	Y	stereo / mono	Y	Y	mini	2.0	-	-	-
16.		Sony A850	Y	- / -	-	-	mini	2.0	-	-	-
17.		Sony A900	Y	- / -	-	-	mini	2.0	-	-	-

It is notable that the A99 II 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 Sony A99 II (unlike the M1) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the A99 II 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 Sony and YI. Further information on the features and operation of the A99 II and M1 can be found, respectively, in the Sony A99 II Manual (free pdf) or the online YI M1 Manual.

Review summary

So how do things add up? Is the Sony A99 II better than the YI M1 or vice versa? The listing below highlights the relative strengths of the two models.

Advantages of the Sony Alpha ALT-A99 II:

• More detail: Offers more megapixels (42.2 vs 20.2MP) with a 48% 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 live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• Better sound: Can connect to an external microphone for higher quality sound recording.
• Better sound control: Has a headphone port that enables audio monitoring while recording.
• Easier framing: Has an electronic viewfinder for image composition and settings control.
• Easier setting verification: Features an LCD display on top to control shooting parameters.
• More detailed LCD: Has a higher resolution rear screen (1229k vs 1040k dots).
• More flexible LCD: Has a full-flex screen for odd-angle shots in portrait or landscape orientation.
• More selfie-friendly: Has an articulated screen that can be turned to be front-facing.
• Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
• Faster burst: Shoots at higher frequency (12 vs 5 flaps/sec) to capture the decisive moment.
• Better sealing: Is weather sealed to enable shooting in dusty or wet environments.
• Sharper images: Has hand-shake reducing image stabilization built-in.
• Easier device pairing: Supports NFC for fast wireless image transfer over short distances.
• 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.

Reasons to prefer the YI M1:

• Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
• Fewer buttons to press: Has a touchscreen to facilitate handling and shooting adjustments.
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• More compact: Is smaller (114x64mm vs 143x104mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 568g or 67 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.
• More affordable: Was introduced into a lower priced category (89 percent cheaper at launch).

If the count of individual advantages (bullet points above) is taken as a guide, the A99 II is the clear winner of the match-up (22 : 8 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 Sony A99 II 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 partial and cannot reveal, for example, the shooting experience and imaging performance when actually working with the A99 II or the M1. 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 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 (USD)	Street Price
1.		Sony A99 II	..	..	4.5/5	85/100	4.5/5	4.5/5	Sep 2016	3,199	ebay.com
2.		YI M1	..	..	..	69/100	..	..	Sep 2016	349	ebay.com
3.		Canon 5DS R	5/5	+	..	83/100	5/5	4.5/5	Feb 2015	3,699	ebay.com
4.		Canon SX730	..	+	..	..	4/5	4/5	Apr 2017	399	ebay.com
5.		Fujifilm X-A3	..	..	..	74/100	4.5/5	4/5	Aug 2016	399	ebay.com
6.		Nikon 1 J5	..	..	..	..	4.5/5	4.5/5	Apr 2015	399	ebay.com
7.		Nikon D850	4.5/5	+ +	5/5	89/100	4.5/5	5/5	Jul 2017	3,299	amazon.com
8.		Panasonic GF7	4/5	+	..	..	4.5/5	4.5/5	Jan 2015	499	ebay.com
9.		Panasonic GX850	..	+	..	76/100	4.5/5	4.5/5	Jan 2017	549	ebay.com
10.		Pentax K-1	5/5	..	..	84/100	5/5	5/5	Feb 2016	1,799	ebay.com
11.		Sony A7R II	5/5	+ +	5/5	90/100	5/5	5/5	Jun 2015	3,199	ebay.com
12.		Sony A7R III	..	+ +	4/5	90/100	4.5/5	5/5	Oct 2017	3,199	ebay.com
13.		Sony A7R IIIA	..	+ +	4/5	90/100	4.5/5	5/5	Apr 2021	3,199	amazon.com
14.		Sony A7S II	5/5	+	..	..	4.5/5	5/5	Sep 2015	2,999	ebay.com
15.		Sony A99	5/5	..	..	84/100	4.5/5	4.5/5	Sep 2012	2,799	ebay.com
16.		Sony A850	3/5	..	..	75/100	..	4.5/5	Aug 2009	1,999	ebay.com
17.		Sony A900	..	+ +	..	+ +	4.5/5	5/5	Sep 2008	2,999	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The review scores listed above should be treated with care, 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. 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 are interested in seeing how other cameras pair up, just make your choice using the following search menu. As an alternative, you can also directly jump to any one of the listed comparisons that were previously generated by the CAM-parator tool.

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