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5.
Gently turn (by hand) the Scheimpflug adjustment nut at the lower left of the Lens Holder (reference 4
Image 11-12) against the Lens Holder front plate without disturbing the projected image.
6.
Turn in the set screw at the lower left of the Lens Holder (reference 14 Image 11-12) without disturbing the
projected image. Use a 3mm Allen wrench.
Note: Ensure that the edges of the projected test pattern remain in place on the screen. Any
movement of the image will affect the Scheimpflug adjustment.
Tip: Fasten the set screw and the Scheimpflug nut alternately, without disturbing the projected image,
until the Scheimpflug nut and set screw are completely tightened.
24
14
4
Image 11-12
7.
Fasten the lock nut at the lower left of the Lens Holder. Use a 10mm nut driver.
11.4 Back Focal Length adjustment
When to adjust the Back Focal Length?
If a lens is used with a throw ratio suited for the application, (lens selection depends on projection distance
and screen size) typically one would NEVER need to adjust the Back Focal Length of the projector.
A Back Focal Length adjustment is only required in case the Focus range of the installed lens does not
capture the projection screen either for FLAT and/or for SCOPE. In other words, when it is impossible to focus
the image on the screen for FLAT and/or for SCOPE. Note that the lenses for the Athena projector are
varifocal. So, switching between FLAT and SCOPE (zoom action) requires a readjustment of the focus.
What is Back Focal Length adjustment?
Back Focal Length adjustment means moving the lens plane (Lp), thus the Lens Holder front plate, closer to or
further from the DMD plane. The closer the lens plane to the DMD plane the further the focus range (Fr) of the
lens will be.
Lp1
Lp2
DMD
Image 11-13
Do not abuse the Back Focal Length adjustment of the Lens Holder. Neglecting this will result in
loss of image quality because of the lens design. Cases requiring Back Focal Length adjustment
normally indicate incorrect lens choice (throw ratio).
Fr1
Fr2
Scheimpflug
R5906790 /04
Athena
107
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