The LingLung series cine lenses are calibrated to the standard M4/3 back focus before leaving the factory. However, the flange focal distance of different M4/3 cameras may vary slightly. To facilitate compatibility with different cameras and achieve the best-imaging effect, the LingLung series is equipped with a quick back focus adjustment mechanism. The back focus adjustment lever is located between the aperture ring and the rear mount of the lens.

During the adjustment process, please follow the steps below.
1. Prepare your shooting subject. You can use a "Siemens Star resolution chart" and ensure it is printed clearly;
2. Mount the lens onto the camera;
3. Adjust the aperture to the maximum aperture T2.9;
4. Adjust the focal length to the telephoto end, 24 mm or 70 mm;
5. Adjust the focus ring to make the subject as sharp as possible;
6. Adjust the focal length to the wide-angle end, 10 mm or 20 mm;
7. At this point, be sure to keep the focus ring unchanged, and only adjust the back focus adjustment ring to make the subject as sharp as possible. If the focus ring moves, please restart from step 4;
8. Repeat steps 3 to 7 two or three times. When the optimal focus position remains the same across all focal lengths, the adjustment is complete.    The final position of the back focus adjustment lever represents the distance that the flange focal distance needs to compensate. The situation may vary for each camera, so please adjust repeatedly to ensure sharp focus at both the wide-angle and telephoto ends;

9. After the adjustment is completed, lock the screw on the back focus adjustment ring to lock the flange focal distance. Theoretically, if you switch to a different camera, you will need to readjust the back focus. If necessary, it can be used in conjunction with a rangefinder.

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