SystemSolver.py 文件源码

def _aperture(self):
            """
            Determine aperture automatically under a variety of conditions.
            """
            iso = self.iso
            exp = self.exposure
            light = self.lightMeter

            try:
                # shutter-priority mode
                sh = self.shutter   # this raises RuntimeError if shutter has not
                                   # been specified
                ap = 4.0 * (sh / (1./60.)) * (iso / 100.) * (2 ** exp) * (2 ** light)
                ap = np.clip(ap, 2.0, 16.0)
            except RuntimeError:
                # program mode; we can select a suitable shutter
                # value at the same time.
                sh = (1./60.)
                raise



            return ap