5. Lenses & lens holder
Image 5-19
If no, use the zoom barrel on the lens to zoom in or out.
How to focus?
1. U se the “+” and “-” focus keys on the local keypad to focus the image on the screen.
Image 5-20
5.6 Scheimpflug adjustment
What has to be done ?
The lens holder has to be adjusted s o that the “sharp focus plane” of the projected image falls together with the plane of the screen
(Fp1→Fp2). This is achieved by changing the dis tance between the DMD plane and the lens plane (Lp1→Lp2). The c loser the lens
plane comes to the DMD plane the further the shar p focus plane w ill be. It can sometim es happ en that you won’t be able to get a
complete focused ima ge on the screen due to a tilt (or swing) of the lens plane with respect to the DM D plane. This is also known
as Sheimpflug’s law. To solve this the lens plane must be placed parallel with the DMD plane. This can b e achieved by turning the
lens holder to rem ove the tilt (or swing) between lens plane and DM D plane (Lp3→Lp4).
SCREEN
DMD
Lp1
Lp2
Fp1
Fp2
SCREEN
DMD
Lp3
Lp4
Fp3
Fp4
(Scheimpflug)
Image 5-21
Scheimpflug principle
Scheimpflug principle
The "plane of sharp focus" c an be changed so tha
t any plane can be brought into sharp focus. When the DMD plane
and lens plane are parallel, the plane of sharp focus will also be parallel to these two planes. If, however, the lens
plane is tilted with respect to the DMD plane, the plane of s harp focus will also be tilted according to geom etrical and
optical properties. T he DMD plane, the pri
ncipal lens plane and the sharp focus plane will intersect in a line below the
projector for downward lens tilt.
R5905067 DPXK-19B/23B/P 17/09/2012 51
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