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Discussion Starter · #1 ·
I need to figure out what my distance needs to be from the front of my screen to the front of the lenses on my XG-135 projector so I can run my power and cables. I will be using a 1:85 ratio with a screen size of 48" x 89". Can anyone help me out here real quick?

Thanks Rick

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oops, check that, that # is from the XG852, looked at the wrong char ...

The 135LC, at 96" screen width is, according to the installation manual table, 137.66"

At 80" screen width, the table shows 115.36.

Formula for 135LC at 89" is

((25/96 * 89 - 12.5 ) X 5.47 + 71.85) * .977

which is 127.26"

most people say +/- 5% on the range, many move it closer to achieve better phosphor use/increase brightness, so you could go as close as 120.9" or, if required, back to 133.6"

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That is the formula for an LC model and gives a different distance. The non LC distance is 121 inches horizontal from screen plane to green lens given by

Horizontal Distance =((25/96* width -12.5)*4.99+70.28) * 0.977

where width is in inches.

If your screen is a rigid framed unit, you can consider bringing the screen closer to the projector later by remounting the screen on L brackets out from the wall.

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847 Posts

Help. I don't understand that formula..


Can you put real numbers in for an example?

They pulled a talking Barbie off the shelves because one of the phases she spoke was, "Math class is tough". They thought that was a bad message to little girls BUT..

Math Class is tough..



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Heres a old school rule w / 4 * 3 = H for 4:3 format and what the lens are doing, then times 2.

OK we have lets say 80" wide divided by 4 = 20", times 3 is 60" times 2 is 120", conclusion, your off by 1.3"- 8" depending on the model.

In the field with a 145, 144 lens this will get you close. 16:9 you have to use the total width of the screen and think 4:3 format. This is just a basic for that set up and if your using ceiling tile as a ruler, worse case senario. Doug

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25/96 means 25 divided by 96!

For example if the screen width were 80 inches...

substitute 80 for where the formulat says "width" so

((25/96* 80 - 12.5) * 4.99 + 70.28) * 0.977

Which means....

Take 25 and divide by 96

Multiply that result by 80 inches

Subtract 12.5 from that result

Multiply that result by 4.99

Add 70.28 to that result

Finally multiply that result by 0.977 to get the final result in inches.

* means multiply

/ means divide

+ means add

- means subtract

Do multiplication and division before additions and subtractions.

Items enclose in parentheses should be evaluated first.

The number system is base ten using digits written as 0, 1, 2, 3, 4, 5, 6, 7, 8, 9

0 means no units

1 means this many /

2 means this many //

3 means this many ///

4 means this many ////

5 means this many /////

6 means this many //////

7 means this many ///////

8 means this many ////////

9 means this many /////////

If there are more than ///////// it is convenient to write it with more than one digit. Each digit further to the left represents a set of ten units. It is also convenient to represent yet larger groups with more digits each showing groups which are ten times the size of the previous digit.

Sometimes one must represent things less than one. Yes, it is possible for a number to be between none and one. Theses are represented using digits following a "." The first digit to the right of the "." means you take one and divide it into ten equal portions. The number of portions is represented by that first digit to the right of "." Yet smaller portions can be represented with additional digits to the right of the "." much as larger units can be represented with more digits to the left end of the number. ;)
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