Weak current College】 【general formula to help you calculate the projector best projection distance --- Power By】 【China power house network.

Buy projector, we first noticed projector brightness, resolution, contrast, uniformity, and other important parameters, in addition, we also want to make sure the projector's lens and LCD Tablet size and other parameters to the projection distance and screen size suitable for our use, projection distance and screen size and projection of focal length and LCD Tablet size closely related to their mutual relations are as follows:

Known projector screen size is: distance

Minimum projection distance (m) = minimum focal length (m) x screen size (inch) ÷ LCD Tablet size (inches)
Maximum projection distance (m) = maximum focal length (m) x screen size (inch) ÷ LCD Tablet size (inches)

Known projector screen size range are:

Maximum projection screen (m) = projection distance (m) x LCD Tablet size (inches) ÷ minimum focal length (m)
Most small projection screen (m) = projection distance (m) x LCD Tablet size (inches) ÷ maximum focal length (m)

For example:

1, ToshibaTLP-S71 focal length is 26.5mm ~ 31.5mm, LCD Tablet size is 0.7 LCD panels, 85 inch screen.

Minimum projection distance (m) = 0.0265 m x85 inch ÷ 0.7 = 3.217 m
Maximum projection distance (m) = 0.0315 m x85 inch ÷ 0.7 = 3.825 m

2, known: EPSONEMP-6000 focal length is 24.0-38.2mm, LCD Tablet size is 0.8 LCD Panel, projection distance of 4 m, the projection: the biggest and the smallest screen projection screen.

Maximum projection screen (inches) = 4 m x0.8 inch ÷ 0.024 m = 133.3
Most small projection screen (inches) = 4 m x0.8 inch ÷ 0.0382 m = 83 inch

Projection screen size mentioned above, we need to be based on the projection screen size to select the projection screen size, we are now talking about screen size practical for screen diagonal length, in inches. Generally our ruler ticks m, and volume of long and relatively easily, so it is helpful to know that according to screen size (inch) getting the screen width (m) and screen height (m)

Length unit conversion formula: 1 inch = 2.54 cm = 0.0254 m

Normal screen width and height of the ratio of 4: 3, so be by the Pythagorean theorem:

Screen width (m) = screen size (inch) x0.0254 m/inch x0.8 = screen size ÷ 50
Screen height (m) = screen size (inch) x0.0254 m/inch x0.6 = screen size ÷ 66
The units are meters

According to this formula:

60-inch screen at a width of 60 ÷ 50 = 1.2 (m) height of 60 ÷ 66 = 0.909 (m)
150-inch screen width is 150 ÷ 50 = 3 (m) height of 150 ÷ 66 = 2.27 (m)
200-inch screen with a width of 200 ÷ 50 = 4 (m) height of 200 ÷ 66 = 3 (m)

According to the above calculation company, we can own calculation, of course, now there are some software available for use, if you want to be lazy, you can download one.