Gerjan says the S-M-C 1:4.5/500 focus just past infinity.
I did adjust mine, however not using any screwdrivers. I did have to try many helical threading combinations to get part of the inner rear element group to gain 1mm more movement range. The two helicals need to be threaded onto correct positions from their maximum range of motion to allow full range of focus adjustment to include infinity & a little beyond -- that must seem like gibberish unless you have done it.
The improvement in infinity photo quality is easy to see; compares with quality closer.
Tip: Photograph a distant laser point to see how still is the camera mounting system.
For some fun mount the laser on the camera & walk over to the laser point to watch it move as an assistant simply walks the ground near the tripod!