You may want to check out the forum site Cloudy Nights. Here's a thread in the amateur telescope subforum about the instrument that discovered this comet. The

You may want to check out the forum site Cloudy Nights. Here's a thread in the amateur telescope subforum about the instrument that discovered this comet. There's a photo of the telescope and of Borisov four posts in to the thread. https://www.cloudynights.com/topic/677286-homemade-065m-f-15/ https://www.cloudynights.com/topic/677286-homemade-065m-f-15... That particular subforum is full of people who make their own telescopes in their home shops, and it's a fascinating place to visit. From what I can tell, this particular telescope is an extreme example, an instrument manufactured to professional standards by a well-resourced optics professional working in his spare time.