Question

Why does one prefer to view the image formed at infinity than that formed at near point in microscope/telescope?

Answer 1

1. When you view an image at the near point (25 cm), your eye’s ciliary muscles must contract fully to increase the curvature of the lens. This is called accommodation, and holding this state for a long time causes significant fatigue and headaches.
2. In contrast, when the image is formed at infinity, the light rays entering your eye are parallel. This allows your ciliary muscles to stay completely relaxed. It’s often called “normal adjustment” because it allows for comfortable, long-term observation without straining the eye.
3. While the magnifying power is slightly higher at the near point, the comfort of a relaxed eye usually makes the infinity setting the preferred choice.