DF4510HD | DF4910HD | DDF4510HDV-IM/-SM | DDF4910HDV-IM/-SM
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6.1.3.1
Adjustment for Lenses with a Fixed Focal Length
If the optimum focus cannot be set exactly with the focus ring of the lens, proceed as fol-
lows:
Point the camera at an object with sufficient contrast (e.g. Siemens star).
The distance to the object should be more than 2000-times the focal length.
Open the iris of the lens.
Set the distance on the lens to infinity (∞).
Loosen the locking screw of the back focus adjustment ring.
Set the optimum focus with the back focus adjustment ring.
Tighten the locking screw of the back focus adjustment ring.
6.1.3.2
Adjustment for Lenses with a Variable Focal Length (Zoom Lenses)
If the focus changes as the focal distance changes, proceed as follows:
Note that due to the design of varifocal lenses a refocusing is usually necessary when
changing the focal length.
The following description, therefore, only applies to zoom lenses.
Point the camera at an object with sufficient contrast (e.g. Siemens star) at a distance
of approx. 2 – 3 m.
Open the iris of the lens.
Set the maximum focal length (tele end) on the lens.
Set the optimum focus with the focus ring of the lens.
Set the minimum (shortest) focal length (wide end) on the lens.
Loosen the locking screw of the back focus adjustment ring.
Set the optimum focus with the back focus adjustment ring.
Slightly tighten the locking screw of the back focus adjustment ring.
Beware not to change the position of the back focus adjustment ring.
Set the maximum focal length (tele end) on the lens again and check whether the im
-
age is in focus.
If necessary, readjust the focus with the focus ring of the lens (not with the back focus
adjustment ring).
Set the minimum (shortest) focal length (wide end) on the lens again and check
whether the image is in focus.
You may need to repeat the last 6 steps several times to obtain the best results.
If the image remains in focus throughout the entire zoom range, finally tighten the back
focus adjustment ring.
