Projector tutorial: part 2

When rushing out to buy a projector, one factor that many fail to take into consideration is the screen. There is little point in spending thousands of dollars on half of the equation and then ruining the projector’s potential by using just any old screen, or even worse, projecting it onto a wall.
 
The purpose of a screen is to reflect the maximum amount of projected light back towards the audience without losing image quality. It therefore plays a critical role in the quality of the displayed image. At the same time, the screen should present the image so that everyone in the room can see it clearly, meaning that optimum image quality can only be achieved if the projector and projection screen are working in harmony.
 
With the explosion of the home theatre scene, the construction and materials that domestic screens are available in has become very sophisticated, however for the sake of brevity there are two main points of reference: high and low-gain screens.
 
Screen gain describes how well a projection screen can make a projected image appear brighter. Like gamma adjustment, a screen gain of 1.2 will make a projected image look 20% brighter than it would if the same image were projected on a screen with a gain of 1.0, or neutral.
 
A high-gain screen has a highly reflective surface that is designed to provide optimal brightness for images. The main advantage of this type of screen is that it performs well in brighter environments -- the disadvantage is that it has a narrow viewing area (approximately 60 degrees).
 
A low-gain screen’s main advantage is that it provides a much larger viewing area (around 110 degrees). The downside is that you will need to reduce ambient light to achieve the same level of perceived image brightness as a high-gain unit.
 
Screen size
 
Screen size is mainly determined by the ‘throw’ distance from the projector to the screen, and will be approximately the same for most home theatre projectors, which normally use short-throw lenses.
 
One of the common mistakes that users make is aiming for the largest image they can possibly achieve. The issue with this is that a projector can only throw a constant level of light, and when this is spread over a larger area the perceived brightness of the image is adversely affected. If you want a huge screen size, buy a projector with the highest ANSI Lumens output you can find -- or turn out the lights.
 
Aspect ratio
 
When choosing the aspect ratio of a screen it is best to reflect the default or preferred aspect ratio of your projector. If your projector has a native 4:3 resolution then match it up to a 4:3 screen. This will give you the best effect, by filling all available screen space and optimising the projected image.
 

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