Which statement is NOT true when comparing Galilean to Keplerian?

Which statement is NOT true when comparing Galilean to Keplerian?

• A. The exit pupil is located inside the telescope for Galilean
• B. Galilean creates an upright, magnified image
• C. Galilean has a longer tube length and is heavier
• D. Galilean has a smaller FOV

Answer: (C)

When comparing Galilean and Keplerian telescopes, the key difference is how the optics and focal lengths determine tube length and image properties. A Galilean uses a convex objective with a concave eyepiece, which yields an upright, magnified image and a relatively short tube because the tube length is roughly the objective focal length minus the eyepiece focal length (remember the eyepiece is negative). In contrast, a Keplerian uses two convex lenses, so the tube length is about the sum of the focal lengths, making it longer and typically heavier. The exit pupil in a Galilean forms inside the telescope, while in a Keplerian it forms outside the instrument. The Galilean design also tends to have a smaller apparent field of view than a Keplerian for the same magnification. So the claim that Galilean has a longer tube length and is heavier is not true.

When comparing Galilean and Keplerian telescopes, the key difference is how the optics and focal lengths determine tube length and image properties. A Galilean uses a convex objective with a concave eyepiece, which yields an upright, magnified image and a relatively short tube because the tube length is roughly the objective focal length minus the eyepiece focal length (remember the eyepiece is negative). In contrast, a Keplerian uses two convex lenses, so the tube length is about the sum of the focal lengths, making it longer and typically heavier. The exit pupil in a Galilean forms inside the telescope, while in a Keplerian it forms outside the instrument. The Galilean design also tends to have a smaller apparent field of view than a Keplerian for the same magnification. So the claim that Galilean has a longer tube length and is heavier is not true.