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1036024A / May 2001
3
KTC-105 B/W
Camera
A
Back focus adjustment lock screw
B
Back focus adjustment ring
Back focusing is used to match the lens’ back focal length with the camera’s imaging device. It
enables the camera to be focused correctly during setup and ensures that the image remains
sharp and crisp under various lighting conditions, taking into account changes in the lens’ depth
of field. To achieve correct back focus, adjustments should be made in low light—at night or in
simulated low-light conditions and with the iris fully open (lowest f-number). Back focusing should
always be done when the depth of field is at its minimum. The lens’ depth of field will be reduced
when the iris is fully open. (Depth of field: The proportion of the field of view that is in correct
focus. Depth of field will decrease when the focal length is long, the f-number is small (iris fully
open), or the object distance is short.)
To adjust the back focus, perform the following:
NOTE: This adjustment should be carried out only if the lens cannot be focused through the entire picture using
the lens focus ring.
1)
Operate the camera and view an object approximately 75 ft away.
2)
If the lens has a focus ring, set it to infinity by turning it fully clockwise as viewed from the
front of the camera.
3)
If the lens has a manual iris, set the lens iris adjustment to the widest opening or lowest
f-number. If the lens has an auto iris, place the appropriate neutral-density filter in front of the
lens to simulate low-light conditions, which forces the iris to open fully.
4)
Unscrew the back focus adjustment lock screw so that the back focus adjustment ring turns.
5)
Adjust the lens’ focal position (with the filter in place, if used) by gently turning the back focus
adjustment ring to achieve the sharpest image.
6)
Retighten the back focus adjustment lock screw carefully while ensuring that the focus does
not change.
7)
Position the camera for the required view and, if needed, adjust the focus using only the
focus ring on the lens.
8)
If you are using an auto iris lens, adjust the DC level for optimum performance.
C
PWR LED
D
Auto iris lens connector
E
Terminal block
F
Level
When using a DC auto iris lens, the switch should be set to DC and the lens level adjusted to
provide 1-V pk-pk composite video under full lighting conditions.
G
VIDEO OUT (BNC)
H
Backlight Compensation
NOTE: The backlight function is available only if the camera is used with a manual lens.
Backlight compensation enables the camera to electronically compensate for bright
background lighting and to show details that would otherwise be silhouetted.
NOTE: Compensation may be insufficient when the background is extremely bright.
I
Iris mode switch
J
Lens mode switch
