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 f77.92 is 

• 1/125 s. 

• 1/100 s. 

• 1/50.0 s

• 1/25.0 s

Answer 1

So as we know Shutter speed is proportional to the frame rate so,

$E\propto F$

So,

E3 F

So we get,

$\frac{1/200s}{E_2}=\frac{f/2.8}{f/7.92}$

So we get, minimum shutter speed for