The eye changes its f-number by
A)using the iris to change the size of the pupil.
B)using the ciliary muscle to change the focal length of the lens.
C)Both a & b are correct.
D)The eye does not change its f-number.

Question

Quizplus · Accepted Answer

The eye changes its f-number by both using the iris to change the size of the pupil and using the ciliary muscle to change the focal length of the lens. The f-number is determined by the ratio of the focal length of the lens to the diameter of the pupil, so changing either the focal length or the diameter of the pupil will result in a change in the f-number.

The Eye Changes Its F-Number by