Which telescope is typically longer and heavier?

• A. Keplerian
• B. Galilean
• C. Both
• D. None

Answer: (A)

Keplerian telescopes use two converging lenses with their focal lengths spaced a distance roughly equal to the sum of those focal lengths. For a given magnification, this longer separation means a longer tube and larger lenses, which makes the instrument heavier. Galilean telescopes pair a converging objective with a diverging eyepiece, allowing the lenses to be placed closer together, producing a shorter, lighter tube for similar magnification. So, in terms of physical size and weight, the Keplerian design is typically longer and heavier.