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14 Pelco Manual C1900M (4/99)
Information Box
Information Box
Backfocusing
MANUAL IRIS
AUTO IRIS
A
B
• Set all other switches on the
back of the camera to the left
(deactivated or OFF), includ-
ing the CCD Iris switch.
• This step is the same as the
one for DC SERVO, except
that the AUTO IRIS VIDEO/
DC switch is set to VIDEO.
* With CCD Iris OFF,
the Iris Level control is
inactive.
CCD IRIS*
AGC
TURBO AGC
L
H
IRIS LEVEL
DC SERVO
VIDEO SERVO
The purpose of backfocusing is to make the adjustments necessary for the picture to remain in focus throughout the camera‘s zoom
range, which is the case, for instance, in motorized zoom, auto iris configurations. Manual iris lens/camera combinations also need to
be back focused. Follow the general instructions listed below to adjust back focus appropriate to your camera/lens combination.
AUTO IRIS
VIDEO DC
NOTE: Most auto-iris configurations are associated with motorized zoom
lenses, so the instructions below are based on that assumption.
• This step is the same as for
DC servo.
• This step is the same as for
DC servo.
• For AUTO-IRIS applications
using VIDEO servo, set the
IRIS LEVEL control pot to
the H position.
BACKFOCUS ADJUSTMENT
• Adjust focus to far, zoom to
wide angle.
• Adjust C/CS adjustment
ring on the camera for the
best picture.
• Zoom to a close object; ad-
just lens controller or focus
for best picture.
• Repeat above until lens re-
mains in focus throughout
the zoom range (far to near).
• Tighten the lock screw.
The ability of a zoom lens to remain in focus throughout its zoom range is known as tracking.
• Make sure the Auto Iris Video/
DC switch is in the DC posi-
tion. Use a neutral density
filter or some other physical
means to decrease the
amount of light entering the
camera lens so that the auto-
iris response is to open the
iris up as wide as possible.
AUTO IRIS
VIDEO DC
• Finally, use the IRIS LEVEL
adjustment to adjust for best
picture.
• Adjust other settings on cam-
era as needed.
LENS TYPE
Generic example of best
setting for C-mount lens
Picture will be out
of focus on either
side of best setting.
Best setting
Adjustment
Ring
Lens/Camera Setup and Backfocusing
BLC