A 80 mm focal-length lens is employed to focus an image on the film of a camera. The maximum distance allowed among the lens and the film plane is around 120 mm. How far ahead of the film must the lens be if the object to be photographed is at the given distance from the lens?
(i) 10.4 m away
(ii) 4.8 m away
(iii) 1.4 m away
(iv) Find the closest object this lens could photograph sharply?