Grundig GCA-B0002B, Owner'S Manual

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4.3. Back Focus Adjustment
When to adjust the back focus:
Back Focus refers to the distance from the rear lens element to the camera focal plane.
It is only required to adjust the back focus only when the focus cannot be adjusted
throughout its zoom range.
Requirements:
Tools required when carrying out back focus adjustment include:
1. Back focus adjuster (in the package of the camera)
2. Test chart / contrasting object
How to adjust the back focus:
Step 1: Set the camera on a stable mount, with the test chart or object at least 75 feet
(23 meters) away (or as far as possible). Please loosen the focus ring's retaining screw
with the supplied back focus adjuster.
Step 2: Make sure the iris is wide open. Therefore, it is advised to keep the environment
in low light condition. To open the automatic lens completely, please use a neutral
density filter. With this filter it is possible to simulate a low light condition so that the lens
can open up completely.
Step 3: Adjust the focus to infinite far ( ∞ ).
Step 4: Turn the zoom to the wide angle (telephoto) position, and then focus with the
back focus on the subject.
Step 5: Set the zoom to the most extreme wide angle (telephoto) position.
Step 6: Focus on the object with the back focus ring. Check now whether it is possible to
adjust the focus with the back focus ring also in the wide angle range.
Step 7: Repeat steps 3 ~ 6 until the focus can be adjusted throughout the zoom range.
When using a zoom lens and changing the focal length, the focus does not need to be
adjusted again once the back focus adjustment has been completed. This does not
apply to vario lenses.
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