I never built my own telescope, but a lot of real astronomers did, and many of the earliest members of the profession made considerable contributions to our understanding of optics.

The larger the aperture of a telescope, the more resolution the instrument is capable of, assuming the telescope optics are of high quality.

We are used to calling an instrument of this kind in optics a telescope, and the radioastronomical counterparts are therefore briefly named "radio telescope" .