Vinten Radamec Free-d - Manual (Page 24)

Vinten Broadcast Ltd free - d ™ Installation Manual V1.4.4
Page 24 of 46
7.6 CCD centering
Position a real object and a virtual object so they can both be seen in the
centre of the composite picture, with the objects chosen so that their relative
horizontal and vertical positions can be easily determined. Zoom the studio
camera lens fully in and out whilst observing the relative positions of the
objects in the centre of the field of view (ignore the rest of the image). Ensure
there is no vertical or horizontal shift (slippage) between the real and virtual
objects as the zoom is changed.
If there is any shift as the zoom is changed the CCD centering needs to be
altered; this is usually an adjustment within the virtual-set system. Note that a
video timing error (ie, the camera video and the background video not being
co-timed at the input to the keyer) can result in a similar symptom.
7.7 Video delay
There is 40ms in 625 or 33ms in 525 (2 fields) delay associated with free-d™
tracking system. This means that the real camera output must be delayed by
this amount (plus delays associated with the virtual set system) before being
combined with the virtual image in the chromakeyer. Please note that in poll-
mode (VR system triggered) the delay is 50ms regardless of video format.
Only when genlocked with an appropriate studio reference will the delay be
reduced to 1 frame (2 fields).
Perform some small, sudden, pan movements and note whether the real
and virtual parts of the image move at the same time (ignore, for the
moment, whether they move by the same amount).
If the real part of the image leads the virtual part of the image, more delay in
the camera output is needed. If the real part lags the virtual part, less delay in
the camera output is needed. Note that it is usually only possible to achieve
adjustments in steps of one video field (20 ms) or frame (40 ms). To equalise
the delay to a closer tolerance, a variable software ‘data delay’ must be
provided by the virtual set system.
7.8 Horizontal view angle
With the lens at its fully telephoto setting, pan the camera from side to side
whilst observing the relative positions of a distant real object and a distant
virtual object (Ideally the objects should be at the same distance from the
camera).