A 35 mm camera equipped with a 45 mm focal length lens is used to photograph a tree 15 m tall.The aperture of the lens is set at f/ 2.The aperture diameter at f/ 2,in mm,is closest to:
A)23
B)14
C)18
D)27
E)31

Question

Quizplus · Accepted Answer

The aperture diameter at f/2 is given by the formula:Aperture diameter = Focal length / f-number= 45 mm / 2= 22.5 mmThe closest answer choice is 23 mm, which is choice A.

A 35 Mm Camera Equipped with a 45 Mm Focal