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8 Pelco Manual C1901M (4/99)
Information Box
Information Box
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 backfocused. Follow the general instructions listed below to adjust backfocus appropriate to your camera/lens
combination.
LENS TYPE
MANUAL IRIS
AUTO IRIS
.
LH
LEVEL
B
A
DC SERVO
• To Adjust Backfocus, set CCD
Iris switch to the OFF position.
• 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.
• Adjust the LEVEL POT on the
camera for best picture.
• Adjust other settings on cam-
era as needed.
ON OFF
CCD Iris
Generic example of best
setting for C mount lens
Picture will be out
of focus on either
side of best setting
c
cs
Best setting
Auto -Iris lenses used with Black and White (B/W) cameras use
DC SERVO control ONLY.
Lens/Camera Setup and Backfocusing
BACKFOCUS ADJUSTMENT
• Adjust focus to far, zoom to
wide angle.
• Adjust C/CS adjustment Ring
on the camera for the best pic-
ture.
• Zoom to a close object; adjust
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
Iris operation controlled by DC motor voltages from camera.
LEVEL control is ON THE CAMERA