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7.
Fine tune the focus with the focus ring on the lens.
8.
Remove the welder's glass from in front of the lens.
9.
Adjust the iris of the lens for the best picture quality.
5) Zoom lens back focus adjustment
The objective of back focusing a zoom lens is similar to that of a fixed focal length camera except
the back focus is also adjusted to maintain the focus when "zooming" the lens in and out on a
scene.
1.
Choose an object at the farthest range set for viewing with a zoom lens.
2.
Make sure the iris of the lens is wide open. Do this by adjusting the camera at night or use
a welders glass in front of the lens.
3.
Adjust the focus to the stop on the far range.
4.
Adjust the zoom on the lens to obtain the widest picture.
5.
Loosen the back focus lock screw.
6.
Adjust the back focus ring for the clearest picture.
7.
Tighten the back focus lock screw.
8.
Adjust the zoom on the lens to the far telephoto position.
9.
Adjust the back focus ring for the clearest picture.
10. Adjust the zoom on the lens back to the widest picture.
11. Loosen the back focus screw.
12. Re-adjust the back focus for the clearest picture.
13. Tighten the back focus lock screw.
14. Repeat the previous steps as necessary to maintain a clear picture throughout the entire
zoom range.
13
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