Since received a lot asking about how to adjust back focus of Pictor Zoom, today we'll talk about this. About the process, it's 5 steps in total.
Step 1: To start with, prepare a Siemens Star charts, or other black-and-white(high-contrast) resolution chart to test.
Step 2: Attach your Pictor Zoom Lens to the camera;
Step3: Rotate the iris to wide open
Step4: Set up Siemens Star chart at 15M(4.9 feet) away from the camera(flange), and make sure the target is in the image center.
Adjust the operating 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.
Zoom out to the widest, focus on the target until the target is sharpest, and mark down the focus distance as S2.
At this moment the lens is under Parfocal.
Those are the reference video:
Official video by DZOFILM TEAM
The more detailed version by NOYB NOYB in actual using: