Originally Posted by
Doremus Scudder
Let's see... opening the aperture one stop doubles the amount of light hitting the paper. Decreasing it on stop halves the light hitting the paper.
Therefore, closing one stop would require twice the exposure time to compensate for the halving of the intensity. So, your 23-second exposure should become 46 seconds if you close the aperture one stop.
Due to the inverse square law, the amount you have to open the aperture to double the light is subject to a factor of the square root of 2. Time, on the other hand, follows simple doublings and halvings to get a stop difference.
So, you can think of your time sequence, 8, 11, 16, 22, 32, 45... as half-stop intervals, not full-stop intervals. Apertures on the lens, 8, 11, 16, ..., however, are full stops.
Best,
Doremus
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