DZOFILM 12290654, User Manual

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Pictor Zoom series lenses will all go through flange back test with
shims based on S35 standard before shipping, but flange back distance
can vary on different cameras. If the flange back distance is incorrect,
the camera will not focus at the correct distance.
How to Adjust Back Focus of Pictor Zoom
1.To start with, prepare a Siemens Star chart, or other black-and-white
(high-contrast) resolution chart to test;
2.Attach your Pictor Zoom lens to the camera;
3.Rotate the iris to wide open;
4.Set up Siemens Star chart at 1.5M(4.9 Feet) away from the camera
(flange), and make sure the target is in the image center.
A. Zoom in to the longest focal length, focus on the target until the target is
sharpest, and mark down the focus distance as S1.
B. Zoom out to the widest, focus on the target until the target is sharpest,
and mark down the focus distance as S2.
C.If the figure S2 ＜ S1, increasing shim(s) is needed; If S2 ＞S1, then reduce
the shim(s).
D.Repeat step A to C until S2=S1. At this moment the lens is under Parfocal.
The testing target should lay on
the center of image, and 1.5M away
from the camera sensor
Maximum T-stop