Indeed, ProjectorCentral's Paul Vail discussed the issue in a Q&A column answering the question, " How Do I Calculate Screen Size and Seating Distance for My Home Theater?". If not, you'll probably find it helpful to at least touch on those two steps first.ĭeciding on screen size is worth an article of its own. If you already know the screen size and image brightness you want, you can skip to the section on calculating lumens. When it comes to calculating the lumens you need, you can replace most of the arithmetic with a simple look-up table, which you'll find at the end of this article.Ĭalculating your lumen needs for a particular screen size and lighting doesn't have to be so hard. There's not much you can do about most of these complications, but in this article I'll address one in particular. Then there's the math part of it to negotiate. Unfortunately, it's not so simple in practice, with all sorts of ifs, ands, and buts to account for. Start with the screen size and the image brightness you need, and then calculate how many lumens it will take to give you that desired image brightness. The throw distance td is equal to the throw ratio tr times the screen width w.How bright a projector you need to light up a screen-whether in a dark room with controlled lighting or in a family room or conference room with window light that changes throughout the day-is easy to determine, in principle at least. Given the projector throw ratio and the screen’s width, the following formula will calculate the throw distance. The minimum and maximum throw ratio should be documented for every projector and is needed to calculate the throw distance. The distance varies by the lens used in the projector and the screen’s size. How to Calculate Projector Throw DistanceĪ projector needs to be installed a specified distance from the screen to allow the image to fill the screen correctly. Use the following chart as a guide for choosing the right screen brightness for your room.Ĭhart showing the optimal screen brightness for various types of rooms 0-15 ft-L You might be wondering how many foot-lamberts you need for a good experience? SMPTE recommends at least 16 foot-lamberts for a dark cinema. The brightness in foot-lamberts is equal to the projector lumens times the screen gain, divided by the area of the screen in square feet. Use the following formula to calculate the brightness of your screen.įt-L = lumens × gain / screen square feet Some screens also incorporate gain to increase the amount of light reflected to the viewers, increasing the brightness. The projector’s luminosity and the size of the screen both contribute to the overall brightness. The screen’s brightness is typically measured in foot-lamberts or candela per square meter. You can also use an aspect ratio calculator to solve the ratio.Ī projector screen’s brightness is one of the most important factors in a good cinematic experience. Then, divide each dimension by the greatest common factor to get each part of the aspect ratio. Find the greatest common factor between the screen’s width in pixels or inches and the height in pixels or inches. It’s possible to calculate a screen’s aspect ratio given either the image’s resolution or the width and height. Don’t forget to account for the ideal screen height for the optimal viewing experience. We go into much more detail about calculating screen size on our screen size calculator. Screen height = AR h × diagonal / √(AR w 2 + AR h 2) The screen width is equal to the aspect ratio width AR w times the screen diagonal divided by the square root of the aspect ratio width AR w squared plus the aspect ratio height AR h squared. Screen width = AR w × diagonal / √(AR w 2 + AR h 2) Use the formulas below to calculate a screen’s width and height. You can calculate the size of a projector screen given the diagonal measurement using the aspect ratio and the Pythagorean theorem. Try our TV size and distance calculator to calculate the optimal viewing distance for a television. The viewing distance d is equal to the screen width w divided by 2, times the tangent of 180 minus the viewing angle θ divided by 2. Use the following formula to calculate the viewing distance for a given viewing angle. The Society of Motion Picture and Television Engineers (SMPTE) recommends a viewing angle of 30°. THX recommends a viewing angle of 26° to 40°, with a preferred angle of 36° to 40° if possible. Various standards define the proper viewing angle for viewing content on a projection screen. The optimal viewing distance from a screen depends on the screen’s width.
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