Brightness
The brightness of the image produced by the projector at maximum backlight brightness. Usually, the average brightness of the screen, derived from a special formula, is indicated. The higher it is, the less the image depends on ambient light: a bright projector can provide a clearly visible image even in daylight, but a dim one will require dimming. On the other hand, increasing brightness reduces contrast and accuracy of colour reproduction.
Accordingly, when choosing this parameter, you need to consider the conditions in which you plan to use the projector. So, for office or school/university use, a brightness of at least 3000 lm is desirable — this allows you to get normal visibility without obscuring the room. In turn, among the top models a very low brightness can be found, because. such projectors are usually installed in rooms specially designed for them with good darkness level. And in ultra-compact devices it is impossible to achieve high brightness for technical reasons.
Detailed recommendations on the optimal brightness for certain conditions can be found in special sources. Here we note that anyway, it is worth choosing according to this indicator with some margin. As mentioned above, as brightness increases, contrast and colour quality decrease, and you may need to use the projector at a reduced brightness to achieve the desired picture quality.
Brightness ANSI Lumens
This parameter largely determines the ability of the projector to work in a well-lit room. For a dark room, 1000 lumens is enough to make the projection picture bright, rich, clear and understandable. But when working in a lit room, the projector will need at least 3500-4000 lumens. Do not confuse ANSI lumens with Peak lumens. These are two different brightness standards. To convert one type of brightness to another, you need to multiply Peak lumens by 10-12. The result will be an approximate value of ANSI Lumens.
However, experts do not recommend chasing high ANSI lumen brightness values. There are many professional projectors with brightness up to 3500 lm. The lower the brightness, the lower the power consumption, and at the same time, the life of the illuminator increases. Of course, if the projector will be installed in a work office or classroom where good lighting is required, it is recommended to purchase a model with ANSI Lumens brightness of 4000 lumens and more.
Dynamic contrast
The dynamic image contrast provided by the projector.
Dynamic contrast ratio is the ratio between the brightest white and darkest black colour that a projector can produce. Recall that the quality of colour reproduction and detailing depend on contrast, the higher this indicator, the lower the likelihood that details will be indistinguishable in bright or dark areas. However, dynamic contrast is a rather specific parameter. The fact is that when it is calculated, the brightest white at the maximum brightness settings and the darkest black at the minimum are taken into account. As a result, the figures in this column can be very impressive, but it is impossible to achieve such a contrast within one frame.
By introducing this parameter, the manufacturers went to a certain trick. However, this is not to say that dynamic contrast has nothing to do with image quality at all. Projectors can use automatic brightness control, in which the overall brightness, depending on the "picture" on the screen, can increase or decrease. This format of work is based on the fact that the human eye does not need too bright areas on a general dark background and very dark areas on a bright one, the image is normally perceived even without it. The maximum brightness difference achievable in this mode of operation is exactly what described by dynamic contrast.
Size
The size of the panel/chip affects the depth and final quality of the image. The larger the panel/chip, the more light it is able to process, which means the picture will be clearer and more structured. The average projector has a sensor of 0.5-0.7″, advanced projectors use sensors of 1.2-1.5″ and more.
Throw distance, min
The closest distance to the screen that the projector can be used on. Typically, this is the minimum distance at which the image from the projector remains in focus.
This parameter is especially important if the device is to be placed at a small distance from the screen (for example, in a cramped room). Some modern projectors are able to work normally at a distance of 10 – 20 cm. Also note that the throw distances are determined primarily by the lens, and if the initial range of these distances does not suit you, perhaps the situation can be solved by replacing the optics.
Throw distance, max
The farthest distance from the screen that the projector can be used on. This is the maximum distance at which the image remains in focus and maintains acceptable brightness — at least enough for viewing in a darkened room on a high-quality screen.
It is necessary to choose according to this parameter taking into account the expected operating conditions and the distances to be dealt with. At the same time, it's ok to have a certain margin for the maximum distance — since, as already mentioned, it is usually indicated for an perfect screen and a darkened room, and such conditions are not always available. Also note that although the throw distances depend on the lens, not every projector with an interchangeable lens allows the installation of more "long-range" optics than the standard one — the device may simply not have enough brightness for an increased distance.
Auto keystone correction
Automatic image alignment when the projector is moved away from the screen. If the central axis of the projection ray does not coincide with the central axis of the screen, then an effect in the form of a so-called keystone occurs. The projector uses a special software algorithm to emulate screen and projection ray alignment. This is not effect the quality of colour reproduction or the depth of textures, but the image can be aligned. The auto keystone correction feature works on the basis of a proximity sensor, which evaluates the difference between the sizes of the edges of the picture. If a keystone effect occurs, the projector straightens the picture without user participation.
Bluetooth
Bluetooth version supported by the projector.
By itself, Bluetooth technology is designed for direct wireless connection between different devices. In projectors, this connection is most often used to broadcast sound to wireless headphones or speakers; Other uses of Bluetooth are possible (for example, connecting a remote control), but they are rare. Thus, you can not pay much attention to the specific version of Bluetooth supported by the projector — all versions are compatible with each other at least in basic functionality (including sound transmission).
Wi-Fi
Wi-Fi standard supported by the projector.
Wi-Fi is known mainly as a method of wirelessly connecting to the Internet and local networks. In addition, more recently, this technology has also been used for direct connections between wireless devices. Accordingly, the methods of using Wi-Fi in projectors may also be different. Thus, some models are capable of connecting to local networks to work with content via DLNA (see above); in others, such a connection is used for control from a computer or other network device; in others, a “remote control” like a smartphone or tablet can connect directly via Wi-Fi.
As for Wi-Fi versions, the most popular options in modern technology - Wi-Fi 4 (802.11n) and Wi-Fi 5 (802.11ac) - are quite compatible with each other, and the difference between them in this case is not critical. Therefore, you don’t need to pay much attention to these details when choosing.
There are also
Wi-Fi ready projectors, which do not have Wi-Fi out of the box, but when connecting the appropriate adapter (purchased separately) are capable of a wireless connection.