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When selecting different zoom lens settings, the operator should be aware of the change in
the Minimum Object Distance (MOD) as the viewing angle changes. At the full telephoto
position in air and water, the MOD is approximately 1.5m, while at the full Wide-Angle
position it decreases to the front of the window.
3.6 FOCUS CONTROL
The RS-485 CEX-HD camera is normally operated in Auto-Focus mode. This provides
nearly ideal focusing when the camera is aimed at different scenes and tracks while the
zoom control is actuated. In some instances where there are objects in a scene at different
distances and there is a need for focusing on specific objects, operation in a Manual Focus
Mode may be required. This is achieved by sending the manual Focus command followed
by the direct Focus position command to the IC-LINK. The focus function continues until
the camera reaches its commanded direct Focus position or the lens focus limit is reached.
To restore Automatic Focus Control: the IC-LINK must send the Auto Focus command.
Generally, most in-air users are able to stay in Auto-Focus mode all the time. The one set
of conditions which may force the operator to switch into Manual mode, is when viewing a
relatively close object that does not have much sharp detail. This occurs because the
Auto-Focus system relies on increasing the sharpness of edges in the viewed image in
order to optimize the focus.
If there are no edges to utilize for this process, the Auto-Focus will not be able to properly
compensate and may even tend to "hunt" around the optimum focus point. Focus hunting
may also be caused by low illumination. Again, if the camera is unable to properly sharpen
edges due to insufficient video level, Auto-Focus operation will be less than optimal.
Switching over to Manual mode by sending direct Focus commands is the best option.
Underwater users have a special set of considerations which may make Auto-Focus
operation more difficult. Some underwater environments contain particles in suspension
and un-dissolved solids that tend to reduce the detail of a viewed image. If the image does
not have sharp detail, the Auto-Focus system will have a difficult time obtaining correct
focus. In those cases, manual operation may be a better choice.
3.7 COMPUTER CONTROL
All camera features are controlled using half duplex 2-wire RS-485. The ROS IC-LINK must
be used to operate the CEX-HD.
