Sony A9 II vs YI M1
The Sony Alpha A9 II and the YI M1 are two digital cameras that were revealed to the public, respectively, in October 2019 and September 2016. Both the A9 II and the M1 are mirrorless interchangeable lens cameras that are based on a full frame (A9 II) and a Four Thirds (M1) sensor. The Sony has a resolution of 24 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.
Going beyond this snapshot of core features and characteristics, what are the differences between the Sony Alpha A9 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.
An illustration of the physical size and weight of the Sony A9 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 A9 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 (41 percent) than the Sony A9 II. Moreover, the M1 is substantially lighter (59 percent) than the A9 II. It is worth mentioning in this context that the A9 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. A larger imaging sensor will tend to go along with bigger and heavier lenses, although exceptions exist. You can compare the optics available for the two cameras in the Sony FE Lens Catalog (A9 II) and the Micro Four Thirds Lens Catalog (M1). Mirrorless cameras, such as the two under consideration, have the additional advantage of having a short flange to focal plane distance, which makes it possible to mount many lenses from other systems onto the camera via adapters.
The battery packs of both cameras can be charged via USB, which can be very convenient when travelling.
The table below summarizes the key physical specs of the two cameras alongside a broader set of comparators. 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.
|1.||Sony A9 II||129 mm||96 mm||76 mm||678 g||690||Y||Oct 2019||4,499|
|2.||YI M1||114 mm||64 mm||34 mm||281 g||450||n||Sep 2016||349|
|3.||Canon SX730||110 mm||64 mm||40 mm||300 g||250||n||Apr 2017||399|
|4.||Fujifilm X-A3||117 mm||67 mm||40 mm||339 g||410||n||Aug 2016||399|
|5.||Nikon Z6||134 mm||101 mm||67 mm||675 g||310||Y||Aug 2018||1,999|
|6.||Nikon 1 J5||98 mm||60 mm||32 mm||231 g||250||n||Apr 2015||399|
|7.||Panasonic GX850||107 mm||65 mm||33 mm||269 g||210||n||Jan 2017||549|
|8.||Panasonic GF7||107 mm||65 mm||33 mm||266 g||230||n||Jan 2015||499|
|9.||Sony A7S III||127 mm||97 mm||81 mm||699 g||600||Y||Jul 2020||3,499|
|10.||Sony A7C||124 mm||71 mm||60 mm||509 g||740||Y||Sep 2020||1,799|
|11.||Sony A7R IV||129 mm||96 mm||78 mm||665 g||670||Y||Jul 2019||3,499|
|12.||Sony A7 III||127 mm||96 mm||74 mm||650 g||610||Y||Feb 2018||1,999|
|13.||Sony A7R III||127 mm||96 mm||74 mm||650 g||650||Y||Oct 2017||3,199|
|14.||Sony A9||127 mm||96 mm||63 mm||673 g||650||Y||Apr 2017||4,499|
|15.||Sony A7S II||127 mm||96 mm||60 mm||627 g||370||Y||Sep 2015||2,999|
|16.||Sony A7 II||127 mm||96 mm||60 mm||599 g||350||Y||Nov 2014||1,999|
|17.||Sony A99||147 mm||111 mm||78 mm||812 g||500||Y||Sep 2012||2,799|
|Notes: Measurements and pricing do not include easily detachable parts, such as add-on or interchangeable lenses or optional viewfinders.|
Any camera decision will naturally be influenced heavily by the price. 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 92 percent) than the A9 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. Then, after the new model is out, very good deals can frequently be found on the pre-owned market.
The size of the sensor inside a digital camera is one of the key determinants 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 A9 II features a full frame sensor and the YI M1 a Four Thirds sensor. The sensor area in the M1 is 73 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 A9 II has a native 3:2 aspect ratio, while the one in the M1 offers a 4:3 aspect.
With 24MP, the A9 II offers a higher resolution than the M1 (20.2MP), but the A9 II nevertheless has larger individual pixels (pixel pitch of 5.94μm versus 3.34μm for the M1) due to its larger sensor. Moreover, the A9 II is a much more recent model (by 3 years) than the M1, and its sensor will have benefitted from technological advances during this time that further enhance the light gathering capacity of its pixels.
The resolution advantage of the Sony A9 II implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A9 II for good quality output (200 dots per inch) amounts to 30 x 20 inches or 76.2 x 50.8 cm, for very good quality (250 dpi) 24 x 16 inches or 61 x 40.6 cm, and for excellent quality (300 dpi) 20 x 13.3 inches or 50.8 x 33.9 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 A9 II has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.
The Sony Alpha A9 II has a native sensitivity range from ISO 100 to ISO 51200, which can be extended to ISO 50-204800. The corresponding ISO settings for the YI M1 are ISO 100 to ISO 25600 (no boost).
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.
| DXO |
|1.||Sony A9 II||Full Frame||24.0||6000||4000||4K/30p||25.0||14.0||3434||93|
|2.||YI M1||Four Thirds||20.2||5184||3888||4K/30p||..||..||..||..|
|5.||Nikon Z6||Full Frame||24.3||6048||4024||4K/30p||25.3||14.3||3299||95|
|6.||Nikon 1 J5||1-inch||20.7||5568||3712||4K/15p||21.1||12.0||479||65|
|7.||Panasonic GX850||Four Thirds||15.8||4592||3448||4K/30p||23.2||13.3||586||73|
|8.||Panasonic GF7||Four Thirds||15.8||4592||3448||1080/60p||..||..||..||..|
|9.||Sony A7S III||Full Frame||12.0||4240||2832||4K/120p||23.7||13.9||2520||86|
|10.||Sony A7C||Full Frame||24.0||6000||4000||4K/30p||25.0||14.7||3407||95|
|11.||Sony A7R IV||Full Frame||60.2||9504||6336||4K/30p||26.0||14.8||3344||99|
|12.||Sony A7 III||Full Frame||24.0||6000||4000||4K/30p||25.0||14.7||3730||96|
|13.||Sony A7R III||Full Frame||42.2||7952||5304||4K/30p||26.0||14.7||3523||100|
|14.||Sony A9||Full Frame||24.0||6000||4000||4K/30p||24.9||13.3||3517||92|
|15.||Sony A7S II||Full Frame||12.0||4240||2832||4K/30p||23.6||13.3||2993||85|
|16.||Sony A7 II||Full Frame||24.0||6000||4000||1080/60p||24.9||13.6||2449||90|
|17.||Sony A99||Full Frame||24.0||6000||4000||1080/60p||25.0||14.0||1555||89|
Many modern cameras are not only capable of taking still images, but also of capturing video footage. Both cameras under consideration have a sensor with sufficiently fast read-out times for moving pictures, and both provide the same movie specifications (4K/30p).
Beyond body and sensor, cameras can and do differ across a range of features. For example, the A9 II has an electronic viewfinder (3686k 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 following table reports on some other key feature differences and similarities of the Sony A9 II, the YI M1, and comparable cameras.
|1.||Sony A9 II||3686||n||3.0||1440||tilting||Y||1/8000s||10.0||n||Y|
|6.||Nikon 1 J5||none||n||3.0||1037||tilting||Y||1/4000s||60.0||Y||n|
|9.||Sony A7S III||9440||n||3.0||1440||swivel||Y||1/8000s||10.0||n||Y|
|11.||Sony A7R IV||5760||n||3.0||1440||tilting||Y||1/8000s||10.0||n||Y|
|12.||Sony A7 III||2359||n||3.0||922||tilting||Y||1/8000s||10.0||n||Y|
|13.||Sony A7R III||3686||n||3.0||1440||tilting||Y||1/8000s||10.0||n||Y|
|15.||Sony A7S II||2400||n||3.0||1229||tilting||n||1/8000s||5.0||n||Y|
|16.||Sony A7 II||2400||n||3.0||1230||tilting||n||1/8000s||5.0||n||Y|
One feature that differentiates the A9 II and the M1 is in-body image stabilization (IBIS). The A9 II reduces the risk of handshake-induced blur with all attached lenses, while the M1 offers no blur reduction with lenses that themselves do not provide optical image stabilization.
The reported shutter speed information refers to the use of the mechanical shutter. Yet, some cameras only have an electronic shutter, while others have an electronic shutter in addition to a mechanical one. In fact, the A9 II is one of those camera that have an additional electronic shutter, which makes completely silent shooting possible. However, this mode is less suitable for photographing moving objects (risk of rolling shutter) or shooting under artificial light sources (risk of flickering).
The Sony A9 II 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 A9 II and the M1 write their files to SDXC cards. The A9 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 A9 II supports UHS-II cards (on both slots), while the M1 cannot take advantage of Ultra High Speed SD cards.
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 A9 II and YI M1 and, in particular, the interfaces the cameras (and selected comparators) provide for accessory control and data transfer.
| WiFi |
| NFC |
|1.||Sony A9 II||Y||stereo||mono||Y||Y||micro||3.1||Y||Y||Y|
|6.||Nikon 1 J5||-||stereo||mono||-||-||micro||2.0||Y||Y||-|
|9.||Sony A7S III||Y||stereo||mono||Y||Y||full||3.2||Y||-||Y|
|11.||Sony A7R IV||Y||stereo||mono||Y||Y||micro||3.1||Y||Y||Y|
|12.||Sony A7 III||Y||stereo||mono||Y||Y||micro||3.1||Y||Y||Y|
|13.||Sony A7R III||Y||stereo||mono||Y||Y||micro||3.1||Y||Y||Y|
|15.||Sony A7S II||Y||stereo||mono||Y||Y||micro||2.0||Y||Y||-|
|16.||Sony A7 II||Y||stereo||mono||Y||Y||micro||2.0||Y||Y||-|
It is notable that the A9 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 A9 II (unlike the M1) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.
Both the A9 II and the M1 are recent models that are part of the current product line-up. The A9 II replaced the earlier Sony A9, while the M1 does not have a direct predecessor. Further information on the two cameras (e.g. user guides, manuals), as well as related accessories, can be found on the official Sony and YI websites.
So how do things add up? Which of the two cameras – the Sony A9 II or the YI M1 – has the upper hand? Is one clearly better than the other? A synthesis of the relative strong points of each of the models is listed below.
Arguments in favor of the Sony Alpha A9 II:
- More detail: Offers more megapixels (24 vs 20.2MP) with a 11% higher linear resolution.
- Better image quality: Features a larger and more technologically advanced imaging sensor.
- Richer colors: The sensor size advantage translates into images with better, more accurate colors.
- More dynamic range: Larger sensor captures a wider spectrum of light and dark details.
- Better low-light sensitivity: Larger sensor produces good images even in poorly lit environments.
- 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.
- More detailed LCD: Has a higher resolution rear screen (1440k vs 1040k dots).
- More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
- Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
- Faster burst: Shoots at higher frequency (10 vs 5 flaps/sec) to capture the decisive moment.
- Less disturbing: Has an electronic shutter option for completely silent shooting.
- Longer lasting: Can take more shots (690 versus 450) on a single battery charge.
- Better sealing: Is weather sealed to enable shooting in dusty or wet environments.
- Sharper images: Has hand-shake reducing image stabilization built-in.
- Faster data transfer: Supports a more advanced USB protocol (3.1 vs 2.0).
- 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: Supports Ultra High Speed (UHS-II) SDXC cards on both slots.
- More modern: Reflects 3 years of technical progress since the M1 launch.
Reasons to prefer the YI M1:
- More compact: Is smaller (114x64mm vs 129x96mm) and will fit more readily into a bag.
- Less heavy: Has a lower weight (by 397g or 59 percent) and is thus easier to take along.
- More affordable: Was introduced into a lower priced category (92 percent cheaper at launch).
- More heavily discounted: Has been around for much longer (launched in September 2016).
If the count of individual advantages (bullet points above) is taken as a guide, the A9 II is the clear winner of the match-up (23 : 4 points). However, the relevance of individual strengths will vary across photographers, so that you might want to apply your own weighing scheme to the summary points when reflecting and deciding 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 Sony A9 II and the YI M1 place the cameras among the top in their class? Find out in the latest Best Mirrorless Interchangeable Lens Camera listing 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 A9 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.
This is where reviews by experts come in. The adjacent summary-table relays the overall verdicts of several of the most popular camera review sites (amateurphotographer [AP], cameralabs [CL], 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.
|1.||Sony A9 II||..||..||90/100||5/5||5/5||Oct 2019||4,499|
|2.||YI M1||..||..||69/100||..||..||Sep 2016||349|
|3.||Canon SX730||..||+||..||4/5||4/5||Apr 2017||399|
|4.||Fujifilm X-A3||..||..||74/100||4.5/5||4/5||Aug 2016||399|
|5.||Nikon Z6||5/5||..||..||4.5/5||5/5||Aug 2018||1,999|
|6.||Nikon 1 J5||..||..||..||4.5/5||4.5/5||Apr 2015||399|
|7.||Panasonic GX850||..||+||76/100||4.5/5||4.5/5||Jan 2017||549|
|8.||Panasonic GF7||4/5||+||..||4.5/5||4.5/5||Jan 2015||499|
|9.||Sony A7S III||..||+ +||91/100||4.5/5||5/5||Jul 2020||3,499|
|10.||Sony A7C||3.5/5||..||86/100||4/5||4/5||Sep 2020||1,799|
|11.||Sony A7R IV||5/5||+||91/100||4.5/5||5/5||Jul 2019||3,499|
|12.||Sony A7 III||..||+ +||89/100||5/5||5/5||Feb 2018||1,999|
|13.||Sony A7R III||..||+ +||90/100||4.5/5||5/5||Oct 2017||3,199|
|14.||Sony A9||5/5||+ +||89/100||5/5||5/5||Apr 2017||4,499|
|15.||Sony A7S II||5/5||+||..||4.5/5||5/5||Sep 2015||2,999|
|16.||Sony A7 II||5/5||+||82/100||4.5/5||5/5||Nov 2014||1,999|
|17.||Sony A99||5/5||..||84/100||4.5/5||4.5/5||Sep 2012||2,799|
|Notes: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.|
Care should be taken when interpreting the review scores above, though. The ratings were established in reference to similarly priced cameras that were available in the market at the time of the review. Thus, a score needs to be put into the context of the launch date and the launch price of the camera, and rating-comparisons among cameras that span long time periods or concern very differently equipped models make little sense. Also, please note that some of the review sites have changed their methodology and reporting over time.
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.
Specifications: Sony A9 II vs YI M1
Below is a side-by-side comparison of the specs of the two cameras to facilitate a quick review of their differences and common features.
|Camera Model||Sony A9 II||YI M1|
|Camera Type||Mirrorless system camera||Mirrorless system camera|
|Camera Lens||Sony E mount lenses||Micro Four Thirds lenses|
|Launch Date||October 2019||September 2016|
|Launch Price||USD 4,499||USD 349|
|Sensor Specs||Sony A9 II||YI M1|
|Sensor Format||Full Frame Sensor||Four Thirds Sensor|
|Sensor Size||35.6 x 23.8 mm||17.3 x 13.0 mm|
|Sensor Area||847.28 mm2||224.9 mm2|
|Sensor Diagonal||42.8 mm||21.6 mm|
|Sensor Resolution||24 Megapixels||20.2 Megapixels|
|Image Resolution||6000 x 4000 pixels||5184 x 3888 pixels|
|Pixel Pitch||5.94 μm||3.34 μm|
|Pixel Density||2.83 MP/cm2||8.96 MP/cm2|
|Moiré control||Anti-Alias filter||Anti-Alias filter|
|Movie Capability||4K/30p Video||4K/30p Video|
|ISO Setting||100 - 51,200 ISO||100 - 25,600 ISO|
|ISO Boost||50 - 204,800 ISO||no Enhancement|
|DXO Sensor Quality (score)||93||..|
|DXO Color Depth (bits)||25.0||..|
|DXO Dynamic Range (EV)||14.0||..|
|DXO Low Light (ISO)||3434||..|
|Screen Specs||Sony A9 II||YI M1|
|Viewfinder Type||Electronic viewfinder||no viewfinder|
|Viewfinder Field of View||100%|
|Viewfinder Resolution||3686k dots|
|LCD Framing||Live View||Live View|
|Rear LCD Size||3.0inch||3.0inch|
|LCD Resolution||1440k dots||1040k dots|
|LCD Attachment||Tilting screen||Fixed screen|
|Shooting Specs||Sony A9 II||YI M1|
|Focus System||On-Sensor Phase-detect||Contrast-detect AF|
|Manual Focusing Aid||Focus Peaking||Focus Peaking|
|Max Shutter Speed (mechanical)||1/8000s||1/4000s|
|Continuous Shooting||10 shutter flaps/s||5 shutter flaps/s|
|Electronic Shutter||up to 1/32000s||no E-Shutter|
|Time-Lapse Photography||Intervalometer built-in||Intervalometer built-in|
|Image Stabilization||In-body stabilization||Lens stabilization only|
|Fill Flash||no On-Board Flash||no On-Board Flash|
|Storage Medium||SDXC cards||SDXC cards|
|Second Storage Option||Dual card slots||Single card slot|
|UHS card support||Dual UHS-II||no|
|Connectivity Specs||Sony A9 II||YI M1|
|Studio Flash||PC Sync socket||no PC Sync|
|USB Connector||USB 3.1||USB 2.0|
|HDMI Port||micro HDMI||micro HDMI|
|Microphone Port||External MIC port||no MIC socket|
|Headphone Socket||Headphone port||no Headphone port|
|Wifi Support||Wifi built-in||Wifi built-in|
|Near-Field Communication||NFC built-in||no NFC|
|Bluetooth Support||Bluetooth built-in||Bluetooth built-in|
|Body Specs||Sony A9 II||YI M1|
|Environmental Sealing||Weathersealed body||not weather sealed|
|Battery Life (CIPA)||690 shots per charge||450 shots per charge|
|In-Camera Charging||USB charging||USB charging|
129 x 96 x 76 mm
(5.1 x 3.8 x 3.0 in)
114 x 64 x 34 mm
(4.5 x 2.5 x 1.3 in)
|Camera Weight||678 g (23.9 oz)||281 g (9.9 oz)|
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