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SHEDDING THE LIGHT ON PROJECTION |
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What is Focal Length and Throw Distance?
Focal length is the distance between the lens and its focal point. A smaller focal length indicates a wider-angle lens. The focal length is what will determine how far away your projector will need to be from the screen to project an image of a certain size. Throw distance is determined by the focal length. While focal length is a measurement, usually in millimeters, the throw distance is expressed by a ratio. Throw distance is the length from the projector to the projection surface of a desired size. You can determine the throw distance by multiplying the width of the desired image size by the throw distance. An example helps make this point. If you have a throw distance of 1.5:1 your projector will need to be 15 feet away from a 10 foot wide screen in order to fill the screen.
1.5 x 10 = 15
This formula is helpful when you need to determine projector placement in meeting space or building a home theater. |
