Barco DP2K SLP Series User Manual

10. Scheimpflug
10.4 Back Focal Length adjustment
When to adjust the Back Focal Length?
If a lens is used with a t hrow ratio suited for the application, (lens selection depends on projection distance and screen size) typically
one would N E VER need to adjust the Back Focal Length of the projector.
A Back Focal L ength adjustment is only required in c ase the Focus range of the installed lens does not capture the projection
screen either for FLAT and/or for S CO PE. In other words, when it is impossible to focus the image on the screen for FLAT and/or
for SCOPE. N ote that the lenses for the DP2K SLP -series projector are v arifocal. So, switching between F LAT and S CO PE (zoom
action) r equires a readjustment of the focus.
What is Back Focal Length a djustment?
Back Focal Length a djustment means moving the lens plane (Lp), thus the Lens Holder front plate, closer to o r further from the DM D
plane. The closer the lens plane to the DMD plane the further the focus range (Fr) of the lens will b
e.
SCREEN
DMD
Lp1
Lp2
Fr1
Fr
2
Image 10-13
Do not abuse the Back Focal Length adjustment of the Lens Holder. Neglecting this will result in loss of image
quality because of the len s design. Cases requiring Back Focal Length adjustment n ormally indicate incorrect
lens choice (throw ratio).
Necessary tools
• 10mm nut driver.
• 3mm Allen wrench.
• 13mm nut driver.
How to check the Back Focal Length?
1. Ensure that the throw ratio of the installed lens matches with the requirements of the application ( projection distance and screen
size).
2. Ensure that the correct lens par ameters are activated. (See user guide of the Communicator chapter Installation > Advanced >
Lens parameters)
Caution: Not us ing the correct lens par ameters could result in lens dam age.
3. Perform a lens HOM E & RETURN operation. (See user guide of the Communicator cha p ter Installation > Advan ced > Lens
parameters)
4. Project the green focus test pattern. (screen fi
le “ no m asking” or “no “crop”)
Image 10-14
5. Zoom the lens for max imum image on the screen (WIDE).
6. Is it possible to focus the center of the projected image?
If yes, the Back Focal Length is OK.
If no, the Back Focal Length need s realignment. Proceed with the next procedure.
100
R5906847 DP2K SLP SERIES 02/06/2017

Barco DP2K SLP Series Specifications

General

Brand	Barco
Model	DP2K SLP Series
Category	Projector
Language	English