Comparison LG HF65LS vs LG PF1000

— Smart TV (proprietary system). The operating system of the projector is represented by the proprietary software shell of the manufacturer. Usually such operating systems have an attractive and convenient menu, similar to a traditional Smart TV. A proprietary operating system is developed by the manufacturer for the hardware resources of a particular projector model or a whole line. But, as practice shows, compared to the classic Smart TV, the functionality of proprietary system often has significant limitations, and the system itself, in fact, is a stripped-down version of a full-fledged Smart TV.

— Smart TV (Android AOSP). This type of operating system is a modification of the popular Android OS, mainly notable for being open source. It is a versatile operating system that gives the user much more freedom to create changes and customizations within the system. At the same time, the installation and work stability of certain applications on this platform are not guaranteed, and the overall system management was not specially “tailored” for large screens, which may cause some inconvenience. First of all, such solutions will will generate interest among users who understand the features of the Android OS, like to customize and control everything, and have time for this.

— Android TV. This type of projector has full-fledged Android TV software, spec...ially adapted to work on large screens. In accordance with the name, it is a type of Android OS, specially designed for projectors/TVs, etc. In addition to the common features of all “Androids” (such as the ability to install additional applications, including even games), it has a number of special features: optimized interface, integration with smartphones (including the ability to use them as a remote control), voice search, etc. Thanks to this, TVs with this feature are significantly superior in functionality to models with a Smart TV. Of course, a dedicated processor, graphics subsystem and memory are provided for the operation of a multifunctional OS, and the presence of such hardware resources is reflected in the total cost of the projector. Given the same optical design, models with Android TV will cost more than classic projectors with a simple multi-line menu.

The size of the sensor affects the depth and final quality of the image. The larger the sensor, 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.

The ability of the projector to operate in the rear projection mode (“mirroring” the image).

There are two main types of rear projection. Most often, horizontal mirroring is found in projectors — it is used when installing the device behind a translucent screen. Vertical inversion, in turn, is used in projectors with fixed keystone correction — due to their design, when mounted under the ceiling, such devices must be turned upside down, which requires the corresponding correction of the displayed image.

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.

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.

Diagonal 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.

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.

Vertical keystone correction allows you to align the image when the projection ray is shifted from the centre of the screen in a vertical plane. If the projector is suspended from the ceiling and shines from top to bottom, a vertical keystone occurs. And the function of vertical keystone correction allows you to align the picture.

In most cases, projectors can only correct vertical keystone. But the keystone can also be horizontal if the projection ray is offset from the centre of the screen in the horizontal plane. Advanced models are often equipped with an auto keystone correction feature (see the relevant paragraph). In this case, the keystone is aligned in a fully automatic mode, without user participation.

Horizontal keystone correction allows you to straighten the picture if the projection ray is offset from the centre of the screen in the horizontal plane. A horizontal keystone effect occurs when the projector shines on the screen not from above, as in most cases, but from the side. A horizontal keystone is often combined with a vertical one. In this case, it is necessary to correct the distortion both horizontally and vertically.

Projectors with horizontal keystone correction almost always have vertical keystone correction capability (see the relevant paragraph).