A Lens of Focal Length $45 \mathrm {~mm}$ Is Mounted on A

Multiple Choice

A lens of focal length $45 \mathrm {~mm}$ is mounted on a $35 - \mathrm { mm }$ camera. The lens aperture is set at $f / 2.0$ and the shutter speed set at $1 / 2000 \mathrm {~s}$ . The photographer wants to keep the same exposure (amount of light) , but wants to change the $f$ -number to $f / 8.0$ for greater depth of field. What should be the new shutter speed to maintain the same exposure?

A) $1 / 8000 \mathrm {~s}$
B) $1 / 1000 \mathrm {~s}$
C) $1 / 4000 \mathrm {~s}$
D) $1 / 125 \mathrm {~s}$
E) $1 / 500 \mathrm {~s}$