Infinity adjustment (Speed Booster® only)

Your Speed Booster® is meticulously fine-tuned with specialized test equipment at the factory to be able to focus to infinity for every combination of lens and camera body, and also to ensure optimal optical quality with CRC or floating-element lenses. No adjustments are necessary. Some older lenses which are out of tune due to age and some lower quality optics may not be able to focus to infinity with Speed Booster®. It is possible to adjust Speed Booster® to allow for infinity focus for these lenses. Remember, however, that "if it ain't broke, don't fix it." Do not attempt adjustment unless you are not able to attain infinity focus with your lens.

1. Mark the original position of the glass elements so that you could revert if needed.
2. For Micro Four Thirds Speed Booster ULTRA, loosen the stop screw in a recessed hole next to the lens release button.
3. For other Speed Boosters, loosen the stop screw from the side of the lens mount, underneath one of the bayonets. If you find multiple screws underneath the bayonets, the one which takes a slotted screwdriver is the correct one.
4. Rotate the glass elements.
5. Tighten the stop screw.
6. Test. When focused on an object that is very far away, the distance scale should point at the infinity mark. Caution: always tighten the stop screw before testing. 
7. Repeat adjustment as needed.

OR 

Notice that some autofocus zoom lenses are not true zooms but varifocals. The distance scale may not align exactly with the infinity mark at every zoom position. If that is the case, adjust the lens when zoomed to the middle of its zoom range first and then verify infinity focus at the wide and tele zoom positions.