Question

If a camera lens gives the proper exposure for a photograph at a shutter speed of 1/200 s at an f-stop of f/2.80, the proper shutter speed at f/7.92 is

Answer 1

`(1)/(28.15432)\ s`

Step-by-step explanation:

The factor by which the shutter speed is increased is
`(7.92)/(2.8)`

Exposure time will be increased by

`f=2^{(7.92)/(2.8)}=7.1037\ s`

The proper shutter speed is given by

`(1)/(T)f=(1)/(200)* 2^{(7.92)/(2.8)}=\frac{1}{\frac{200}{2^{(7.92)/(2.8)}}}\\ =(1)/(28.15432)\ s`

The proper shutter speed is
`(1)/(28.15432)\ s`