Astronomers should have quite a lot to do with telescopes. You might say a modern astronomer has little to do with telescopes as imagined by a layperson, that is some glass lenses in a tube on a tripod, but they're still called "telescopes" even when it's a complex arrangement of mirrors housed inside an observatory (or on a satellite, as is the case of the James-Webb telescope).

And an astronomer should absolutely have understanding of those, their intricacies, the optical equations involved, and how to operate them (usually with automated software, but astronomers are the ones writing that software).

Now an astrophysicist has less to do with telescopes, especially if your field is theoretical cosmology, although they still require familiarity with telescopes, practicalities, how observations are made etc. because that is the basis of their theory. So, a cosmologist vs. an astronomer might be a better analog for a computer scientist vs. a software engineer.

And I know that despite doing my own thesis in cosmology, my studies involved a lot of knowledge and teaching about telescopes, including at least one night of observations (it's pretty boring, things are very automated).

Reminds me of the classic The Parable of the Toaster:

https://www.glaver.org/ftp/humor/toaster-fable.txt

I'm pretty sure its a quote from Dijkstra.

> as an astronomer has to do with telescopes

A heck of a lot. Your professor clearly does not know much about astronomy.

Don't astronomers use telescopes?

Tell him he knows little about astronomy and invite him to watch the latest episode of The Sky at Night - a bunch of astronomers gush over a diverse set of telescopes ...

La Palma - Gateway to the Universe (November 9, 2026)

  The team journey to La Palma, where giant new telescopes and cutting-edge science are opening extraordinary new windows on our universe.

Roque de los Muchachos Observatory - https://en.wikipedia.org/wiki/Roque_de_los_Muchachos_Observa...