While viewing through a level telescope and moving the eye slightly, a relative movement occurs between the image of the levelling staff and the cross hairs. The instrument is
A)correctly focused
B)not correctly focused
C)said to have parallax
D)free from parallax.

Question

Quizplus · Accepted Answer

This relative movement indicates the presence of parallax, which occurs when the image of the levelling staff and the cross hairs are not in the same focal plane, leading to an apparent shift when the observer moves their eye.

While Viewing Through a Level Telescope and Moving the Eye