Question

In an external focusing telescope, the focusing of the objective is achieved by:

• A. movement of a negative concave lens
• B. movement of objective
• C. movement of cross-staff
• D. double convex lens

Hint:

External focusing = move objective lens for clarity.

Answer 1

The Correct Option is B

In external focusing telescopes, the objective lens is moved forward or backward to achieve proper focus. This differs from internal focusing, where other optical elements are moved.