Chapter 11.4, Problem 63E

a.

To determine

To find the number of f-stop settings to be moved to accommodate less light.

Answer to Problem 63E

  $2$

Explanation of Solution

Given:

The aperture setting of the camera is given by the formula $n={\log }_2\frac{1}{p}$ where $p$ the fraction of sunlight is. The amount of sunlight on cloudy day is $\frac{1}{4}$ .

Calculation:

Substituting the value of $p=\frac{1}{4}$ in the formula $n={\log }_2\frac{1}{p}$ as follows-

  $\begin{array}{l}n={\log }_2\frac{1}{p}\\ n={\log }_2\frac{1}{\frac{1}{4}}\\ n={\log }_{2}4\\ n=2\end{array}$

Therefore, the number off-stop settings is $2$

b.

To determine

To find the fraction of the daylight accommodation.

Answer to Problem 63E

  $p=\frac{1}{8}$

Explanation of Solution

Given:

The aperture setting of the camera is given by the formula $n={\log }_2\frac{1}{p}$ where $p$ the fraction of sunlight is. The number of f-stop settings is $3$

Calculation:

Substituting the value of $n=3$ in the formula $n={\log }_2\frac{1}{p}$ as follows-

  $\begin{array}{l}n={\log }_2\frac{1}{p}\\ 3={\log }_2\frac{1}{p}\\ 2^3=\frac{1}{p}\\ p=\frac{1}{8}\end{array}$

Therefore, the fraction of daylight is $p=\frac{1}{8}$