Exercise: Shutter speeds

With the camera on a tripod and fixed in front of something that moves continuously across your view, make a series of exposures from the fastest shutter speed on your camera to a very slow one.

These photographs are of a weir on the river Cam; the day was bright and sunny but the weir was out of the sunlight apart from the bottom left corner; all the photographs were taken at a focal length of 43mm. From this viewpoint I could see two sources of water falling - the one on the right is at much higher pressure than that at the back.

Shutter speed 1/2s, f29: at this speed, the flow on the right is completely blurred - barely recognisable as running water. It could be cloud. The other source, however, is less affected by the long exposure, though it appears more opaque than it actually is. The bottom left area of the scene is very over-exposed at this shutter speed.

Shutter speed 1/5s, f29: more detailing is appearing in the mass of foam from the right although it is still very impressionistic, and there is more detail to be seen under the flow at the back - although it is still less transparent than it was to the naked eye. The bottom left is still over-exposed, but there is still more detail here.

Shutter speed 1/6s, f29: it's now possible to see fairly clearly the detail behind the flow at the back, though the left flow is still blurred, and the bottom left is still over-exposed.

Shutter speed 1/8s, f29: there's a lot more detail in the burnt-out bottom left corner at this shutter speed; in addition, in the mass of white foam from the right the rapids are beginning to take shape.

Shutter speed 1/20s, f20: much more detail here; the white foam is starting to look quite murky.

Shutter speed 1\50s, f13: this is now quite recognisable as fast-flowing water - even in the bottom left corner. The green reflection which has appeared as quite a bright light at slower shutter speeds is diffused at this speed.

Shutter speed 1/100s, f9.0: still some blurring - especially in the foreground - but much more definition is appearing; the intermittant nature of the flow at the back is clearer; the green reflection top right has nearly disappeared.

Shutter speed 1/200s, f7.1: still some blurring - the drops of water visible in the top third of the photograph are tear-shaped and the flow at the back is clearly streaked; however, the foam at the front is now fairly lacy compared the earlier photographs. The green reflection is barely visible at this speed.

Shutter speed 1/400s, f5.0: movement in this photograph is still not frozen absolutely sharply - the highlights at the back are still streaking; however, you can see a lot more detail in the foaming water in the bottom two-thirds of the picture - right down to individual bubbles in the water.

Shutter speed 1/1000s, f4.5: at this speed the camera can't cope with the light conditions - the aperture is not sufficient to light up the top third of the picture. However, there is nice lot of detail in the bottom two-thirds, with drops of water frozen in the air.