Is there any way to correct the upside-down image in a Newtonian?
The short answer: No. If you want to view terrestrial subjects such as wildlife, you are better off with a refractor or Cassegrain-type telescope. Newtonians give an inverted image, which is fine for looking out into space where there is no up or down. In theory a prism could be put into a Newtonian to correct the image, but in practice there is never enough focus travel on a Newtonian to fit the prism into the light path. There are some exceptions to this, but they are very rare, and often found only in children’s telescopes.
