micro Journal 1

Focal Point: the point of the axis of a lens to which parallel rays of light converge or from which they appear to diverge after refraction or reflection.

 the focal point in this picture is the red circle.


converge: to tend to a common result or conclusion.

in this picture, the roads converge in the center.

Iris diaphragm: used to regulate the amount of light admitted to a lens or optical system

there is a iris diaphragm in a camera.