Geometrical OpticsMedium
Question
The camera lens has an aperture of f and the exposure time (1/60)s. What will be the new exposure time if the aperture become 1.4 f ?
Options
A.
B.
C.
D.
Solution
aperture =f. exposure time 
sec. area of aperture f2, area ∝ 
New aperture = 104f area = 1.96 f2 Ratio of areas = 1.96 Since area of aparture has increased thus exposure time will desrease in same proportion i.e.,
new time =
sec.
sec. area of aperture f2, area ∝ New aperture = 104f area = 1.96 f2 Ratio of areas = 1.96 Since area of aparture has increased thus exposure time will desrease in same proportion i.e.,
new time =
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