I have a dumb question. If the telescope is always moving in an orbit around L2 and then also around sun, how does it focus at a single area for long durations ?
Two parts to this answer. The short one is that this amount of orbital motion results in very very small differences in angle given the very long distance of the objects it's focused on and the relatively short exposure times (short with respect to the orbital period of the telescope).
The somewhat longer answer is that the spacecraft establishes an orientation using its Control Moment Gyros (CMGs). The ops team could use the CMGs to maintain pointing if this small amount of image smear ever became significant. But the CMGs would probably induce as much image smear as they removed, since they will induce structural vibrations in the spacecraft, so the utility of this approach would be questionable.
