Which telescope produces an upright image?

• A. Keplerian
• B. Galilean
• C. Both
• D. Neither

Answer: (B)

The orientation of the final image in a telescope depends on how the two lenses are arranged. A Galilean telescope uses a concave eyepiece with a convex objective. The objective forms a real image at its focal point, but the concave eyepiece creates a virtual image as you look through it, and this combination preserves the upright orientation of the scene. In contrast, a Keplerian telescope uses two convex lenses; the objective forms a real, inverted image, and the eyepiece magnifies it without re-inverting, so the final image appears upside down. Because the goal here is to have an upright view, the Galilean arrangement is the one that achieves that.