Digital Projection TITAN XG-500, User Manual

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Page 2.10 Rev C March 2008
2. Installation Digital Projection TITAN XG-500 User Manual
Notes
The Throw ratio for a particular
lens is fi xed, but assumes that
the image fi lls the width of the
DMD.
For images that do not fi ll the
width of the DMD, the Throw
ratio is effectively increased. To
correct for this, a Throw Ratio
Factor (TRF) is used.
Lens extension is measured
when the lens is focused at
in
fi nity, and fully extended.
At other focus settings, the
extension could be up to 10mm
less
Useful lens calculations
The following lens calculations may be useful:
Throw ratio = Throw distance
Screen width
Throw ratio factor (TRF) = DMD width in pixels = 1024
image width in pixels image
width in pixels
Therefore:
Screen width = Throw distance
Throw ratio x TRF
Throw distance = Screen width x Throw ratio x TRF
Lens extension
The throw distance calculated above is to the outer end of the lens. For each lens,
the nominal distance between the front of the projector and the outer end of the lens
(lens extension) will be as listed below.
Lens extension
0.8 : 1 fi xed lens 001-734 100 mm (3.9 in)
1.2 : 1 fi xed lens 001-735 75 mm (3.0 in)
1.5 - 1.8 : 1 zoom lens 001-736 47 mm (1.8 in)
1.8 - 2.25 : 1 zoom lens 001-737 1 mm (0.1 in)
2.25 - 3.0 : 1 zoom lens 001-738 5 mm (0.2 in)
3.0 - 4.5 : 1 zoom lens 001-739 5 mm (0.2 in)
4.5 - 7.0 : 1 zoom lens 001-740 12 mm (0.5 in)
lens extension,
measured from front
of corner post