Installing a projector
Installation can be as easy as positioning the projector
on a table or bookcase and running a video cable to your laptop or DVD player.
If you require your projector to be ceiling mounted you will need to run power
and video cables. Although current projectors are designed for easy
installation, Ceiling mounting and running power requires a licensed
Most projectors give you four positioning options:
Simplest of all installations, only requires power connection and
signal connection. Image size can be adjusted by simply
repositioning the projector and altering the zoom lens (when
available). This can also help in reducing the length of the video
cable improving signal quality and eliminating the cost of expensive
- Fixed installation, requires image inversion, cabling for Video
and power to ceiling and a ceiling mount. Before fixing you will
need to calculate the required throw distance for your desired image
size and the image offset (See Below). Please note that ceiling
mounting in hot climates can reduce the effectiveness your
projectors cooling system and may lead to lamp failure.
See your projector manual for instructions on inverting your image.
- Offers the same easy installation as front but requiring
horizontal image inversion and a rear projection screen.
- Requirements are the same as both Ceiling and rear.
If you need to position your projector to the left or right of the room or
above or below the screen. Your image may suffer distortion of the image
dimensions - Keystoning.
this situation it is preferable to use Lens shift over Keystone correction.
Keystone correction is also referred to as 3D-reform and Side-shot.
Lens shift changes the projected image inside the
lens maintaining the maximum resolution of your image.
Keystone Correction squeezes the image displayed on the projection panel
(lcd or dlp etc) to counter the projected image distortion, this reduces
the number of pixels used on the panel and lowers the image resolution.
For example "A" in the above image would be corrected by reducing the
left hand side of the image on the projection panel.
Most projectors have vertical Keystone Correction to correct problems "C and
D" above, only some come with Horizontal Keystone Correction which allows
positioning of the projector to the left or right of the screen. Horizontal
tends to have a lower angle if adjustment than vertical correction.
Angle of Keystoning
When you look at the specifications for projector, Keystone
correction is normally quoted as and angle. This is the largest angle that
the projector can square the image for.
Screen size and Throw distance
normally measured in inches is the diagonal distance "A" shown.
The Throw Distance is the distance
from the lens to the screen surface - "B"
The ratio of Throw distance over Screen size is the
Throw Ratio. This ratio allows you to calculate the image
size at any given distance or the throw distance for any given
- Quoted as a percentage, is the height of the image "H" divided
by the height that the image is projected above the horizontal
from the lens "C".
This should be considered when calculating the position of your
screen especially for ceiling mounting as it reduces the need to
use extendable ceiling brackets to lower your projector. (note:
projectors with Lens Shift do not have a quoted offset)