Barco XDL Installation Manual page 38

Installation preparations
Positioning the projector
Image 4–5 Positioning the projector
The projector should be installed at right angles (horizontally and vertically) to the screen at a distance PD.
Note the distance (A) between lens centre and table surface is slightly variable. This distance (A) is nominal
223 mm in case all feet are turned in completely and the vertical lens shift is set to zero (0).
On axis / off axis projection
The position of the projector with reference to the screen may also be different depending on the installation.
Basically the projector can be positioned in On-Axis or Off-Axis configuration. On-Axis configuration means
that the projector is positioned so as to have the centre of the lens coinciding with the centre of the screen.
Off-Axis projection is obtained by shifting the lens up, down, left or right. Several parameters can be calculated
determining the position in any installation.
Formula to calculate the distance CD for On-Axis projection: CD = SH/2 + B - A
Shift range
The lens can be shifted with respect to the DMD (P) which result in a shifted image on the screen (Off-Axis). A
100% shift means that the centre point of the projected image is shifted by half the screen size. In other words,
the centre point of the projected image falls together with the outline of the image in an On-Axis projection.
Due to mechanical and optical limitations it's recommended to keep the shift values within the field of view (F)
as illustrated below. Within these shift ranges the projector and lens perform excellently. Configuring the
projector outside these shift ranges will result in a slight decline of image quality.
The only method to increase the vertical shift range without a decrease in image quality is by shifting the lens
holder itself. For more info on this, see
38 R5906150 /05 XDL
PD
"Additional vertical shift of the Lens Holder", page
SW
40.