6
5.5 Setting the Back Focus Lock
The back focus is the distance between the lens support on the camera and the image sensor. Optimum focus is
only possible when the correct distance is set. It may be necessary to set the back focus in individual cases due
to production tolerances of the lens. The iris of the lens must be open as wide as possible. (smallest F value) to set
the back focus. For lenses with automatic iris control, you will require a ND filter (gray filter) to prevent the iris from
closing in bright light.
L
M
AL
K
M
L
C mount lens
CS mount lens
Adjustment of flange
focus for fixed focus
lenses
This adjustment (distance between lens casing and sensor surface) is required if a
sharp definition cannot be obtained with the lens focussing, or in order to adjust the
position.
To obtain a sharp definition, point the camera at an object which is at least 000 times
further away from the front of the lens than the focal length. (If the focal length is
7.5mm, the object must be at least 5m distant from the camera).
Open the aperture fully and set the focus to (infinite).
If the lens has automatic exposure control, select a dark object, or better use an ND
filter (64-x) to ensure that the aperture is fully open.
Undo set screw
M
. Turn the lens with the CS mount connection until the definition is
sharp. When finished, retighten screw
M
.
CS mount
L
for CS mount lenses. Insert a C mount-Ring
K
if C mount lenses are used.
Adjustment of flange
focus for variable focus
lenses
To obtain a sharp definition, point the camera at an object which is at least 5 times the
minimum lens distance (MOD) of the lens. (If this is m, the object must be at least 5m
distant from the camera).
Open the iris fully and set the lens to the maximum tele position and focus with the
focus ring.
If the lens has automatic iris control, select a dark object (or use an ND filter, 64-x) to
ensure that the iris is fully open.
Set the lens to the maximum wide-angle position.
Undo set screw
M
and turn the CS ring on the camera until an optimal sharpness is
reached. Repeat the process for checking purposes, if necessary.
When finished, retighten screw
M
.
Note
The value stated in the diagram as
AL
(depth of thread of the lens with CS mount: <-
5mm) must be observed. The camera may be damaged if this value is exceeded. When
installing a lens with CS mount, never use a C mount adapter ring.
Summary of Contents for VKC-1370
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