Panasonic NV-VS3A - Manual (Page 80)

How the Focus Adjustment Works
If you look at an object through a magnifying glass and move i*
closer or further away from your eye, you will reach a point
where the object becomes clearly visible. Being focused or in
focus means that the subject can be seen with optimum clarity
and sharpness. The distance between the lens and the point
where the rays of light come together is called Focal Distance
or Focal Length and depends on the size and shape of the
lens.
Human eyes have lenses too, and when we look at objects at
different distances, the shape of these lenses changes
automatically so that we can always see the objects clearly.
■ Auto Focus Adjustment
The image of the subject enters the Movie Camera through
the lens and is converted into an electrical signal (video signal)
for recording onto tape. Based on this signal, the Auto Focus
System automatically adjusts the focal distance by moving the
focusing lens forward or backwards.
The focus is adjusted on the subject in the centre of the
Finder.
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