Wort des Tages
6 July 2026
aberration
The convergence to different foci, by a lens or mirror, of rays of light emanating from one and the same point, or the deviation of such rays from a single focus; a defect in a focusing mechanism that prevents the intended focal point.
Warum dieses Wort
From Latin aberrare, to wander off: the rays stray from where geometry says they should land. It is not a manufacturing flaw in most cases but a consequence of lens shape, which is why designers stack elements of different glasses to cancel it.
In use
Wide open at the edges you can see the aberration in the star field, so we stop it down a couple and the points tighten up.
Written by our editors to show how the term is used, not a recorded quotation.