How to Adjust Back Focus of DZOFILM Pictor Zoom Lenses?

Hi everyone.

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.

Step5:

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.

Adjust the operating B:

Zoom out to the widest, focus on the target until the target is sharpest, and mark down the focus distance as S2.

Ajust the operating C:

If the figure S2 nicreasing shim(s) is needed.
(For detail shim chart, please click on www.dzofilm.com-download-pictor-page 5)
If S2>S1,
then reduce the shim(s)
(For detail shim chart, please click on www.dzofilm.com-download-pictor-page 5)
Ajust the operating D
Repest step A to C until S2=S1.

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: