dallmeier DF4510H - Adjustment for Lenses with a Fixed Focal Length; Adjustment for Lenses with a Variable Focal Length (Zoom Lenses)

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 sufcient 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 innity (∞).
 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 sufcient 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, nally tighten the back
focus adjustment ring.