InFocus XS1 - Manual (Page 10)

Positioning your projector 10
Obtaining a preferred projected image size
The distance from the projector lens to the screen, the zoom setting, and the video
format each factors in the projected image size.
4:3 is the native aspect ratio of this projector. To be able to project a complete 16:9
(widescreen) aspect ratio image, the projector can resize and scale a widescreen
image to the projector's native aspect width. This will result in a proportionally
smaller height equivalent to 75% of the projector's native aspect height.
Thus, a 16:9 aspect image will not utilize 25% of the height of a 4:3 aspect image
displayed by this projector. This will be seen as darkened (unlit) bars along the top
and bottom (vertical 12.5% height respectively) of the 4:3 projection display area
whenever displaying a scaled 16:9 aspect image in the vertical center of the 4:3
projection display area.
When determining the position of your projector, you should consider its intended
use and input signal aspect ratios. All inputs (other than composite Video being fed
a 16:9 aspect signal) will display in a 4:3 aspect ratio (and will require an additional
33% display height than that of the scaled 16:9 aspect image projection area).
Do not select a permanent projector position based upon a 16:9 projection if you will ever
need to select an input (other than composite Video being fed a 16:9 aspect signal).
The projector should always be placed horizontally level (like flat on a table), and
positioned directly perpendicular (90° right-angle square) to the horizontal center of
the screen. This prevents image distortion caused by angled projections (or
projecting onto angled surfaces).
The modern digital projector does not project directly forward (like older style reel-
to-reel film projectors did). Instead, digital projectors are designed to project at a
slightly upward angle above the horizontal plane of the projector. This is so that
they can be readily placed on a table and will project forward and upwards onto a
screen positioned so that the bottom edge of the screen is above the level of the
table (and everyone in the room can see the screen).
If the projector is mounted on a ceiling, it must be mounted upside-down so that it
projects at a slightly downward angle.
You can see from the diagram on page 12 , that this type of projection causes the
bottom edge of the projected image to be vertically offset from the horizontal plane
of the projector. When ceiling mounted, this refers to the top edge of the projected
image.
If the projector is positioned further away from the screen, the projected image size
increases, and the vertical offset also increases proportionately.
When determining the position of the screen and projector, you will need to account
for both the projected image size and the vertical offset dimension, which are
directly proportional to the projection distance.
4:3 aspect image in a 4:3
aspect display area
16:9 aspect image scaled to a
4:3 aspect display area