Slow everything down with a strong ND filter
Long exposures capture movement in a very different way
Very long exposures are just as photographic a way of treating movement as the frozen moment, and they also show us a world that we can never see with
our eyes alone. Rolling waves, such as those pictured here on the south coast of Mauritius, become more like a low, ground-hugging fog.
The issue here is the sensitivity of the camera’s sensor to light, but not in the way you may think. Sensitivity is usually an issue in low light. If, for example, you want to shoot at 1/125 sec to beat camera shake, and you find your shots are under-exposed even at your lens’s widest aperture, you can simply up the ISO to make the sensor more sensitive – albeit at the risk of increased noise.
But sensitivity can also be an issue in bright light, as the image at the top right illustrates. Shot at midday in the tropics, the scene was bathed in very bright light. Even at my lens’s narrowest aperture (in this case f/20 on a 70-200mm at 200mm) the shutter speed required for a correct exposure at ISO100 was a blistering 1/100 sec – much too fast to blur the movement of the waves.
Since I couldn’t lower the ISO (at least not by much) the solution was to attach two neutral density filters to dramatically reduce the amount of light reaching the sensor, and so enable a much longer exposure of 30 seconds (see Long Exposure Essentials, below, for more on this).
A milky sea was achieved by shooting a 30-second exposure at f/20 and ISO100. I reduced the light entering the lens by fitting two ND filters: an ND500 (nine-stop reduction) and an ND64 (three-stop reduction). Without filters, the shutter speed was 1/100 sec
with filters - 30 secs
without filters - 1/100 sec