Question

What is the f number of a 15 cm diameter, .9 m focal length lens?

Answer 1

Answer:

Explanation:

F − number = f D 1 Page 2 APERTURE AND F-NUMBER 2 If the area of an aperture is doubled, the number of photons that can reach the sensor through the lens is also doubled. The F-number of a lens is the ratio of its focal length divided by the diameter of the aperture (Figure 1)

hope that helps