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Hi-Res. B/W camera instruction manual
ADC 660N and ADC 660P
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10
6. ALC/ELC Select Switch (EE/ELC is ON; ALC/AI is OFF)
This switch is used to select EE (electronic exposure)/ELC (electronic light control)
mode or AI (Auto Iris lens)/ALC (automatic light control) mode. DIP switch 1 is set
to ON for EE/ELC and OFF for AI/ALC.
In the EE/ELC mode, a continuously variable electronic shutter is employed to
automatically control the exposure time of the CCD image sensor according to the
incoming light level. With this mode selected, a fixed or manual iris lens can be
used instead of an Auto Iris lens. In the AI/ALC mode, the CCD shutter speed is
fixed to 1/60 (1/50) sec, and the incoming light level is controlled by the Auto Iris
lens. To use a video-drive type or the DC-drive type of Auto Iris lens, set this
switch to the ALC position.
Cautions
Under bright lighting conditions such as outdoors, use an Auto Iris lens
because the EE/ELC control range is not wide enough under these
conditions.
Under certain unique lighting conditions, the following phenomena may
appear:
Strong smear and/or blooming on highlighted objects such as spotlights
or windows.
Noticeable flicker in the picture and/or color rendition variations. To
avoid this, use an Auto Iris lens.
When operating in EE/ELC mode with manual iris lens, the depth of field of
the image may be less than that obtained by using an AI/ALC lens. Depth
of field varies inversely with the iris opening. Thus, using this camera in
EE/ELC mode with the manual iris lens fully opened may result in less depth
of field and the distant objects in a picture may be seen out of focus.
Fixed iris or manual iris lenses may be used with the linear shutter (EE/ELC
mode) where the scene brightness varies over a limited range.
Do not use the EE/ELC mode when an Auto Iris lens is installed.