Astronomical Telescope
A refracting optical instrument consisting of a long-focal-length objective lens and short-focal-length eyepiece used to observe distant celestial bodies.
Governing formula
M = -f_obj / f_eye, Tube Length L = f_obj + f_eye
SI unit
Dimensionless (×)
In depth
Produces an inverted virtual image at infinity. Magnification equals the ratio of objective focal length to eyepiece focal length.
Examples in the real world
Refracting telescopes used by astronomers to observe lunar craters, Saturn's rings, and Jupiter's moons.