Comparison Xiaomi Mi Action Camera 4K vs SJCAM M20

The presence of a 1/4" threaded socket on the camera body. It is this size that is standard for modern tripods and is used in most of these devices. So this feature allows you to mount the camera on a tripod without using adapters and other additional equipment.

The degree of dust and water protection of the protective case supplied with the camera.

Protected case will save your camera from dust, water, temperature changes, shocks, etc. The specific degree of protection is indicated according to the international IP (Ingress Protection Rating) system, according to which each device is assigned a code of the form IPXX, where X is replaced by specific numbers. The first of them characterizes the protection against the penetration of foreign objects (from 0 to 6, where 0 is no protection). Usually, in boxes for action cameras, this indicator does not go below 5, because otherwise the container would have too large gaps, and its use simply would not make sense. Level 5 provides dust resistance — dust can get inside the case, but in small quantities that do not affect the device inside. Level 6 corresponds to complete imperviousness to dust.

The second digit is protection against liquid ingress (from 0 to 8, where 0 is no protection). Usually, the minimum level of protection against water is 6.

6 — protection against short-term immersion (for example, falling into a sea wave);
7 — protection against temporary immersion under water (up to 30 minutes) to a shallow depth (up to 1 metre), without continuous operation in immersed mode;
8 — protection against immersion to a depth of more than 1 metre for a time of more than 30 m, with the possibility of continuous...operation underwater. The specific level of protection of level 8 can be quite impressive — up to the possibility of diving to several tens of metres.

Note that protective cases for action cameras can be sold separately. Therefore, if the capabilities of the complete container do not suit you, there may be a more secure case on the market. On the other hand, in general, it is still more convenient to buy such an accessory immediately with a camera — so as not to waste time and effort on choosing the right protective case.

The ability of the camera to shoot Ultra HD 4K video.

This format covers several resolutions in which the horizontal frame size is approximately 4K pixels. The most popular in action cameras is 3840x2160 (twice the FullHD frame on each side), but there are other options — for example, 3840x1920, corresponding to an aspect ratio of 2:1. In general, 4K is a kind of successor to Full HD: among HD standards that surpass Full HD, UltraHD is the most popular, in particular, many advanced TVs are produced with 3840x2160 screens. On the other hand, this format is quite demanding in terms of processing power and memory, so it is relatively rare in action cameras, mainly among premium models.

Another important parameter given in this paragraph is the frame rate. The higher it is, the smoother the movement in the frame will be, and the details in dynamic scenes will be visible clearly. However, in UltraHD mode, most modern action cameras produce a very low frame rate — most often 30 fps, and in some models 24 fps or even 15 fps. This video is quite viewable, but fast movement in the frame may look blurry. There are cameras capable of shooting UltraHD at a solid speed of 60 fps — the blurring effect during such shooting is almost imperceptible. However, such a model cost is high.

Frame rate supported by the camera when shooting in slow motion.

In general, such shooting is called “high-speed” because it is carried out at an increased frame rate (more than 60 fps). As a result, when played back at normal speed (60 fps and below), the video looks slow hence the name. This kind of slow-motion can be used just for fun, as an artistic technique, and even for scientific purposes — to capture movement that is too fast for the human eye. In any case, the higher the slow-mo frame rate, the more you can slow down the video and the more advanced the camera is in this regard. On the other hand, the higher the frame rate, the more performant the graphics part should be; and this, in turn, affects the price of the device, sometimes quite noticeably.

We also note that slow-mo shooting may be available only at certain resolutions, not always at maximum. These points can be directly specified in the specs of the action camera.

For models with several lenses, as a rule, this parameter is indicated for each lens.

Most often (unless otherwise indicated), the specifications indicate the field of view by the diagonal of the frame; in some ultra-wide-angle lenses it can exceed 180°. A special case is made up of lenses for which a 360° view is declared: this means that the optics cover the entire hemisphere in front of it. Such lenses are found in panoramic and 360-degree cameras (see “Product type”).

In general, the field of view primarily determines what area of the scene is being captured into the frame. Accordingly, the wider it is, the more space the camera captures, and the lower the likelihood that something that is happening will be off-screen. On the other hand, it is worth considering that a strong increase in the field of view leads to distortions of the “picture”, especially at the edges, as well as, to a decrease in the size of visible objects and a decrease in detail. Detailed recommendations regarding choosing a camera based on this parameter can be found in special sources.

The number of built-in microphones provided in the camera.

This parameter is indicated only for models that have more than one microphone. This design provides additional capabilities, but the range of these capabilities depends on the number of microphones and the features of a particular model. So, most often such devices have two microphones; this can be a pair for recording stereo sound, or one microphone can work to record sound, and the second one can act as a sensor for the noise reduction system (see above). A larger number - 3 or 4 microphones - is found mainly in 360-degree cameras (see “Product type”), where such equipment is used to record “surround” multi-channel sound.

The number of megapixels in the action camera sensor, in other words, the resolution of this sensor(1 megapixel is 1 million photosensitive points).

There is an opinion that the higher the resolution, the better the image quality. It is true from the point of view that manufacturers are trying to install high-resolution sensors in advanced cameras. At the same time, there are no strict dependencies here, and from the technical point of view, the number of megapixels determines only the maximum image resolution that can be captured using this sensor. The quality of this picture will depend both on several features of the sensor itself (size, type, special design solutions), and the specs of the camera. So when choosing, you should focus not so much on the resolution of the image sensor, but on the general class of the camera and reviews with examples of footage.

The maximum resolution at which the action camera can take photos. Specified in pixels horizontally and vertically.

This parameter is directly related to the resolution of the image sensor(see above): the total number of pixels in the photo, usually, corresponds to the number of pixels in the sensor. For example, a photo resolution of 4608x3456 corresponds to a sensor of 15925248 pixels, or approximately 16 megapixels. If the number of pixels in the photo is greater than the claimed resolution of the sensor, then the manufacturer uses software tricks that allow you to improve the photo resolution to a higher one than originally. This reduces the cost of devices but also affects the quality of images.

Theoretically, high-resolution images can provide good detail, but in fact, much depends on the specs of the sensor (primarily physical size) and image processing features.

— Photo during video. The ability to take photos directly while recording a video — usually using a separate button. Thus, it is convenient to fix the most significant moments of what is happening. Such photos are much better in quality than "freeze frames" from the captured video.

— Serial photo shoot. This feature allows you to take several pictures at once in a short period (usually it is a fraction of a second). A series of shots increases the chance of capturing a good moment, which can be very important given the specifics of using action cameras.

— One click recording. The ability to quickly turn on the camera for recording — literally at the touch of a button, by the name. Moreover, such a button works even if the device is turned off. However, the recording inevitably starts with some delay; but often this delay is a fraction of a second.

— Online streaming. Ability to stream video to popular services like YouTube and social networks (Facebook, Instagram, TikTok, etc.). Usually, the online streaming function is implemented when the action camera is connected to the Internet via a Wi-Fi network, less often via a wired connection. Communication with the World Wide Web can be held directly or through a smartphone or computer. It will require the use of appropriate software.

— Time lapse. A special mode of operation of the action camera, in which video recording is carried out at a slower frequency is mainly used for filming slow processes. Thus, for example, a long journey or a long sunset can fit into a 3-minute video.

— Auto-rotate. The function of automatic rotation of the captured photos and videos to the position corresponding to the position of the camera. Without this feature, all footage during playback would be displayed strictly in landscape orientation, and footage shot with the camera upside down or upside down would have to be rotated in a photo or video editor. Usually, at the beginning of video recording, auto-rotation is blocked — so that the position of the frame at any time corresponds to the rotation of the camera itself relative to its original position.

— Photo panoramas shooting. The ability to use the camera to take panoramic photos. In traditional action cameras (see "Product type"), such shooting is carried out as follows: the camera takes several separate photos, which are then glued into one image. Regarding panoramic and 360-degree models (see ibid.), it is worth noting that not all such models support shooting in panoramic format, so it is advisable to check the availability of this function separately.

— Key points labels. The ability to add special marks to the footage that indicate key moments. While viewing such videos, you can go directly to the labels — this is easier than manually searching for the right moment. This feature is especially useful when shooting long videos, as well as when numerous individual files. The label, usually, is placed right during the shooting by pressing a special button or by voice command.

— Night shooting. Special mode for recording in low light conditions. The specific implementation of this function may be different: in some models, the sensitivity of the sensor is increased, in others, shooting in the IR range is used. Accordingly, specific features may vary: not every camera with this function can shoot in complete darkness, and these nuances should be clarified separately.