Left pointing hand navigation decoration Return to “Telescopes from the Ground Up” Left pointing hand navigation decoration
Telescopes from the Ground Up
Get to the root of it Background Leaf decoration
Gregorian reflecting telescope (1663)
Diagram showing the light path in a Gregorian reflector telescope.

Long before the technology existed to make it, James Gregory envisioned a telescope with a parabolic primary mirror.

The telescope’s images would have been free of both chromatic and spherical aberration. By using a mirror, rather than a lens, Gregory eliminated chromatic aberration. The mirror's shape was parabolic, not spherical, eliminating spherical aberration.

Return to “Telescopes from the Ground Up”