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Positioning a projector is not just a simple case of installing the correct bracket to the ceiling
and hoping for the best. The type of lens that the projector has will affect how big the image
can be. The two most important considerations, in selecting the type of lens your projector
should have, are the desired image size and desired or available throw distance. These two
measurements can be used to calculate the lens ‘Throw Ratio’ that is needed. This is the
throw distance to screen width ratio.

All three measurements are directly related so knowing the throw ratio and desired screen
size, it is easy to determine the throw distance.

The simple calculation triangle below can be used:

So 

D=W x R

W=D ÷ R

R=D ÷ W

Example  A projector has a lens whose throw ratio is 0.9:1, the required screen width is
2m what is the throw distance?

D=W x R 

D = 2 x 0.9 = 1.8m

In order to give more flexibility, most projectors have a zoom control. This allows the image to
be adjusted for size without moving the projector. The figures given here indicate that by
using the zoom control, throw ratios of 1.5:1 through to 1.9:1 can be achieved. 
The amount of zoom available is specified as a multiplier.
A quoted zoom value of 1-1.3x means that the image can be enlarged by up to 30% with the
zoom control.

D

Screen sizes are usually measured diagonally. As the throw ratio is determined from the
throw distance and screen width, the diagonal measurement should not be used in the
calculation

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Consider the following triangle in relation to your screen

The most common image format for CTV, PC and projected images is 4:3 (4 by 3). This is
also known as the image aspect ratio. This means that the height measurement is ¾ that of
the width. Using the 3-4-5 triangle rule, the diagonal measurement can be used to calculated
width.

Examples 

Diagonal = 10m Width = (Diagonal ÷ 5) x 4  = 10 ÷ 5 x 4 = 8m
Height = 6m   Width = (Height ÷ 3) x 4  = 6 ÷ 3 x 4 = 8m

Although 4:3 is a popular aspect ratio there are others:

5:4
Some PCs are able to produce SXGA images, which offer a resolution of 1280 dots
horizontally by 1024 dots vertically. This aspect ratio is 5:4 

16:9 and 21:9
The majority of DVD format films are now mastered in Wide-Screen format, of which there are
two popular aspect ratios; 16:9 and 21:9. Sometimes these ratios are quantified with respect
to 1, so expect to see 1.85:1 and 2.35:1 respectively.

Knowing the diagonal measurement, calculating the screen width with these other ratios can
be done in a similar manner.

For 5:4 (1.25:1) Width = (Diagonal ÷ 6.403) x 5
For 16:9 (1.78:1)

Width = (Diagonal ÷ 18.358) x 16

For 21:9 (2.35:1)

Width = (Diagonal ÷ 22.847) x 21

 

Focal Length
This is the distance between the display panel and the focal point. The focal length is usually
printed on the lens ring and is usually preceded with a lower case f. If it is a zoom lens then
two figures will be present, one each for the maximum and minimum zoom. eg. f=32.5-44mm.
This figure can be used to calculate the image size and throw distance values if the size of
the display panel is known. 

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This is the physical component within the projector that creates the image. It can be either an
LCD panel or DMD device.

Calculating Image Size and Throw Distance using Focal Length 
If the throw ratio of the lens is not available then the focal length can be used to calculate the
image size or throw distance, however the dimensions of the display panel are needed.

To calculate the throw distance for a pre-defined image size:

Example
Calculate the throw distance required to give a 2.5m diagonal image. The focal length of the
lens is 44mm and the DMD panel is 20.32mm (Diag)

To calculate the image size from a set distance:

Example
Calculate the image size (diag) at a throw distance of 3m. Focal length is 63.8mm and the
LCD panel is 63.8mm (Diag)

f Focal Length

Display Device

Screen

Focus
Lens

Zoom
Lens

       44mm 

             x 

2500mm (diag)  =  5413mm  (5.413m)

20.32mm (diag)

 

3000mm 

        x      33.25mm (diag)  =  1563mm  (diag)  (1.563m)

63.8mm (diag)

Image and Panel Size must be of the same dimension. i.e. Image and Panel

diagonal measurement OR width measurement.

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Note

• 

This projector may not be able to display images from notebook computers in simultaneous
(CRT/LCD) mode. Should this occur, turn off the LCD display on the notebook computer and output
the display data in “CRT only” mode. Details on how to change display modes can be found in your
notebook computer’s operation manual.

• 

When this projector receives 640 × 350 VESA format VGA signals, “640 × 400” appears on the
screen.

• 

When receiving 1,600 × 1,200 VESA format signals, sampling occurs and part of the image may be
cut as the image is displayed in 1,024 lines.

• 

Multiple signal support
Horizontal Frequency: 15–126 kHz, Vertical Frequency: 43–200 Hz*, Pixel Clock: 12–230 MHz

• 

Compatible with sync on green and composite sync signals

• 

UXGA and SXGA compatible in advanced intelligent compression

• 

AICS (Advanced Intelligent Compression and Expansion System) resizing technology

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Native

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“Plug and Play” function (when connecting to a 15-pin
terminal)
• 

This projector is compatible with VESA-standard DDC 1/DDC 2B. The projector and a
VESA DDC compatible computer will communicate their setting requirements, allowing
for quick and easy set-up.

• 

Before using the “Plug and Play” function, be sure to turn on the projector first and the
connected computer last.

Note

• 

The DDC “Plug and Play” function of this projector operates only when used in
conjunction with a VESA DDC compatible computer.

PAL

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PAL-60

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SECAM

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NTSC

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480I

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480P

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540P

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580I

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580P

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720P

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1035I

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1080I

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