Tuesday, April 1, 2008

The choice of a projection screen

The choice of a projection screen is quite simple in itself, as it is often dictated by the constraints of your installation.

The screen itself is generally made up of a specific supple plastic sheet or a special fabric which, in both cases have undergone a treatment guaranteeing an absolute matt white finish. This white screen may also be framed in black, this border giving a perfect finish to the image which, slightly overlapping the black part of the screen, appears to have a clean boundary.

Projection screens generally being "relatively" easy to make, all manufacturers are capable of realising screen surfaces of good quality. The main differences come from the manner in which the "ensemble" of surface + support are put together. Certain screen surfaces may have very good reflecting qualities but be made of a very supply plastic or a very fine, light tissue which will have an unfortunate tendency to crease with time. The differences in prices of screens with a similar quality of reflection are generally explained by the rigidity of the screen itself: thus, don’t hesitate to touch two screens in order to determine which one will be more resistant. As opposed to a Home Cinema installation, the screen of a cinema is stretched onto a metal frame, which allows it to remain totally flat over time.

White screens:
We’ve seen that a video projection screen is by definition mat white. Effectively, this finish is perfectly suited to most cases where projecting conditions are ideal: absolute darkness and/or a very powerful projector. In certain less optimal configurations, (i.e. projection in daylight conditions), it is possible to opt for video projection screens that posses specific characteristics. Generally, these characteristics are aimed at increasing the luminosity of the overall depiction. We call these "High Gain Screens". These screens possess a variable level of gain allowing you, for example, to give a little helping hand to a tri-tube video projector bought second hand and a little on the weak side. This quality has on the other hand another side to it which can turn out to be a nuisance: the more gain there is, the more the screen’s angle of vision is reduced. It is possible to watch a matt white screen from any angle, without losing anything at all in luminosity. Inversely, a high gain screen may constrict you, depending upon the power of the gain, to sitting at exactly 90° to the screen with a risk of otherwise having a significant loss of luminosity.

Perforated Screens:
A video projection screen may, in addition, be perforated with thousands of holes which allow it to let the sound of loudspeakers through when they’re placed behind the screen. It’s this type of screen that is used in cinemas, because their front speakers are always situated behind the screen. This ideal configuration allows the sound to correspond, in its location, with the action taking place on the screen. There are two types of perforation for screens. The classic perforation, in which the holes are relatively visible, because they are almost one millimetre in diameter. This is not annoying in a cinema, because the spectator is generally far enough away from the screen not to notice the perforations in the screen. This is quite different in the home, however, where the viewer is generally less than five metres from the screen. It is thus important, when choosing a screen, to try it out with regard to the distance that you will be from it when it is installed at home. Generally, the price of a classic perforated screen is not much higher than a non-perforated screen. The second level of perforation is that of micro-perforation. As its name suggests, this type of screen possesses holes that are extremely difficult to detect, which is ideal for configurations where the distance of the viewer from the screen is limited. The only drawback: the price, which is very high.

Here, you’ll find different types of mechanisms on which projection screens are able to be mounted. It is possible to mount any kind of screen on any kind of mechanism. " http://uk.cinenow.com/tutorials/2022

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