Choosing a Camera Lens. The picture size on ordinary 35 -mm camera film is 24 $\mathrm{mm} \times 36 \mathrm{mm}$ . Focal lengths of lenses available for 35 -mm cameras typically include $28,35,50$

(the "normal" lens), $85,100,135,200,$ and 300 $\mathrm{mm}$ , among others. Which of these lenses should be used to photograph the following objects, assuming that the object is to fill most of the picture area? (a) a building 240 $\mathrm{m}$ tall and 160 $\mathrm{m}$ wide at a distance of $600 \mathrm{m},$ and (b) a mobile home 9.6 $\mathrm{m}$ in length at a distance of 40.0 $\mathrm{m} .$