Appendix D: Back Focus Adjustment - Centrix F20 User Manual

Appendix D: Back Focus Adjustment

When to adjust back focus
Back Focus refers to the distance from the rear lens element to the camera focal plane. In most
cases, it is required to adjust back focus only when the camera's lens cannot hold focus throughout
its zoom range.
What requirements
Tools required when carrying out back focus adjustment include:
1. Back focus adjuster (in the IP Camera's package)
2. Test chart / contrasting object
How to adjust 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).
Step 2: Make sure the iris is wide open. Therefore, it is advised to keep the environment in low light
condition.
Step 3: Adjust the focus to infinite far (∞).
Step 4: Turn the zoom to the extreme telephoto position, and then focus on the subject.
Step 5: Set the zoom to wide-angle position.
Step 6: Loosen the back focus ring's retaining screw with the supplied adjuster, and adjust the back
focus ring for sharp picture.
Step 7: Repeat steps 3 ~ 6 until focus can stay the same throughout the zoom range.
Step 8: Tighten the back focus ring's retaining screw to fix the ring.
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