1. Or, more preferably, a light source is so positioned that coma aberration does not change despite a change in a skew angle of the object lens.

2. The invention relates to an object lens (SA) with at least one fluid lens (VFL), which is preceded according to the invention by an afocal or quasi-afocal optical system.

3. Collimation (kol-ă-may -shŏn) The alignment of the optical elements in a telescope.For a simple refractor the only adjustment required is to position the object lens at right angles to the optical axis by adjusting the screws on its supporting cell.