The iris diaphragm and the human eye?

Question

The function of the iris diaphragm is to adjust the amount of light entering the condenser. To what part of the human eye would you compare it?

Answer 1

It can be compared with the radial and circular muscles of the iris.

When the radial muscles contract the circular muscles are relaxed and the pupil size increases. This happens in dim light.

When the circular muscles contract the radials are relaxed and the pupil size decrease. This happens in bright light.