Question

A lens (f-number) has following measurements: diameter is 5.4
Determine the speed of the lens.
(A) 6.32
(B) 6.23
(C) 2.63
(D) 3.26​

Answer 1

Answer:

The f-number of an optical system (such as a camera lens) is the ratio of the system's focal length to the diameter of the entrance pupil ("clear aperture").[1][2][3] It is a dimensionless number that is a quantitative measure of lens speed, and an important concept in photography. It is also known as the focal ratio, f-ratio, or f-stop.[4] It is the reciprocal of the relative aperture.[5] The f-number is commonly indicated using a hooked f with the format f/N, where N is the f-number

Explanation:

b

ans is