Brightness/contrast enhancement
Support by the projector of one or another
technology of brightness/contrast enhancement.
Usually in such case, software image processing is implied to improve brightness and/or contrast (if necessary). Specific processing methods may be different — in particular, in some cases we are actually talking about turning standard content into HDR, and some manufacturers do not specify technical details at all. The effectiveness of different technologies can also be different, and besides, it is highly dependent on the specific content: in some cases, the improvement will be obvious, in others it may be almost imperceptible.
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.
Image size
Size of the image projected by the projector. Usually, it is indicated as a range — from the smallest, at the minimum throw distance, to the largest, at the maximum. About throw distances, see above; here it is worth saying that the choice of diagonal size depends both on the distance between the screen and the audience, and on the format of the projector. For example, to watch a video, the best option is the situation when the distance from the viewer to the image corresponds to 3-4 diagonals, and a relatively large picture can be useful for working with presentations. More detailed recommendations for different situations can be found in special sources; here we only recall that the image must fit on the screen used with the projector.
Throw ratio
The projector's throw distance is vital in determining what size projection screen to use and how far away it should be from the projector. Most projectors have a variable throw ratio. In the extreme positions, these are wide-angle mode (smallest value) and telephoto lens mode (largest value). Knowing these values, you will be able to determine the range of throw distances within which the projector must be placed in order for the projected image to match the specified dimensions of the projection screen.
According to these values, you need to check or set the optical zoom. We divide the larger value by the smaller value, and we get a figure, for example 1.33-2.16: 1.
If we want to calculate whether this projector is suitable for a certain image size, we do this: 1.33*3 (image width)=the distance at which the projector should hang.
AirPlay
The projector supports AirPlay technology. We are talking here about both the original technology (when the presence of AirPlay is simply indicated, without clarification), and about version v.2 - compatibility with this version is directly indicated in the characteristics.
In general, AirPlay is a proprietary Apple technology designed primarily for broadcasting video and audio signals from iPhone, iPad and other Apple gadgets to external playback devices. So it makes sense to specifically look for such a projector mainly if you plan to broadcast content from Apple gadgets to it. However, third-party equipment can also act as a signal source - for example, a laptop with iTunes installed (or another compatible player). In any case, the broadcast is carried out via Wi-Fi, and the devices must be within the same network. The AirPlay bandwidth is enough to work with video in HD resolutions, and the transmitting gadget during such a broadcast also plays the role of a remote control for the receiving device.
In turn, AirPlay v.2 was a development and improvement of the original AirPlay. In the case of projectors, the main innovation is the ability to control playback through the Siri voice assistant.
Number of speakers
The number of built-in speakers provided in the projector.
The
presence of speakers in itself allows user to play sound (for example, accompaniment to the displayed video) without speakers and other additional equipment. However the quality of such sound usually turns out to be low; for a clear sound, you still need external sound system. However, in some cases this is quite enough; in addition, there are projectors with advanced built-in speakers.
The number of speakers can be one or two. In the first case, we are talking only about the playback of monophonic sound, without any surround effect. And two speakers already represent a stereo system. The subwoofer is considered a separate function and does not affect the number of speakers in this paragraph.
Sound power
The nominal power of the sound system installed in the projector.
The higher this power, the louder the sound the device can produce, the better it will be heard in a large room and/or noisy environment. At the same time, it is worth noting two nuances. First, built-in speakers are usually made relatively low-power — otherwise they would take up too much space. Secondly, most modern projectors allow the connection of external sound system (see "Audio connectors"), more powerful than the built-in one. So it makes sense to pay attention to this indicator if you initially plan to use the "native" sound of the projector. Detailed recommendations on the required power for certain conditions can be found in special sources.
