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Verfügbare Sprachen
YW
VL-C780S/H/X
VL-C7400E
VL-C690S/H/X
VL-C6400E
7.AUTO FOCUS CIRCUIT
7-1, Outline: action of AF method of this unit
The AF method of this unit is image processing method. In this method, the principle is utilized that the
clearer the outline of the object image in focus becomes, the more the high frequency component of the
video signal increases.
After experiencing high frequency component extraction, A/D conversion and digital integration, the video
signal is inputted in the AF microcomputer.
Moving the focusing lens back and forth, the AF microcomputer
calculates the increase and decrease of the high frequency component to judge how the object is out of focus.
According to this judgement, it moves the focusing lens so that the high frequency component reaches its
peak.
Not only the video signal but also the lens condition is utilized as information for focusing.
When the iris is stopped down, the depth of field becomes deep, making the change of high frequency
component small. On the contrary, when the iris is opened, the depth of field becomes shallow, making the
change of high frequency component large. Therefore, the focusing speed is controlled according to the
position of the iris, improving the focussing accuracy.
When the zoom is on the telescopic side, the fluctuation of the video signal becomes large and the depth of
field becomes shallow, making the change of high frequency component large. When the zoom is on the
wide angle side, the fluctuation of the video signal becomes small and the depth of field becomes deep,
making the change of high frequency component small.
Therefore, the focusing speed is controlled
according to the position of the zoom, improving the focussing accuracy.
As described above, the AF microcomputer drives the focus motor according to the condition of picture-
taking by combining the main information based on the video signal with the above mentioned
Jens
information.
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