[填空题]
Suppose that a correct ex qwl3lj 29(itrpj-rf+- i +hoiei a5(nvosure is $\frac{1}{250}\,s$ at $f/11$ Under the same conditions, what exposure time would be needed for a pinhole camera (Problem 8) if the pinhole diameter is 1.0 mm and the film is 7.0 $cm$ from the hole? $t_2$ = 1/ s
