English to German Tech/Engineering Photography/Imaging (& Graphic Arts)

The objective lens (2) of telescope has been intensely polished and established to minute tolerances (what so they mean with "established to minute tolerance"... - established to high precision?)

It must be cleaned with care and as seldom as possible to avoid affecting its precision and performance. An inexperienced person must never take the lenses out of their mount.


IM of a telescope.