Magnification and Field of View
A telescope’s magnification is simply the telescope’s focal length divided by the eyepiece’s focal length: Magnification = Telescope FL ÷ Eyepiece FL. A shorter focal-length eyepiece gives higher magnification.
The true field of view — how much sky you actually see — is the eyepiece’s apparent field of view divided by the magnification: True FOV = Apparent FOV ÷ Magnification. Higher magnification always narrows the field of view, which is why low-power, wide-field eyepieces are used for finding objects before zooming in.
Last reviewed August 2026