Published on: 6th Apr 2015
Like most photographic techniques, long exposure (also called "slow shutter speed") is not a new technique, but it is one of the techniques that benefited the most as a result of the ease of experimentation with digital cameras. This technique works especially well for landscapes with fast running water such as waterfalls, river rapids, streams with semi-exposed rocks and obviously the sea.
The easiest to experiment with are waterfalls and streams, as they are normally in shade and that already makes for a slower shutter speed than your average daytime photographs.
The other important piece of equipment is a set of filters that will reduce the amount of light that is let through to the sensor and therefore make the exposure time longer. These filters are called "neutral density" filters and the word"neutral" indicates that they will not interfere with your white balance. Unfortunately, the quality of the filter as well as the time of exposure does have an influence on the neutrality of these filters. But, if you shoot in RAW it is always possible to adjust the white balance in post processing.
They are marked based on the amount of light they will block, and normally are called ND2, ND4, ND8 and ND16 (1, 2, 3 and 4 stops less light respectively). The most expensive one is an ND filter that reduces the light by 10 stops and was made popular by the Lee filter system. It is known as the Big Stopper. You will find similar 10 stop (but also 6 stop) filters from other manufacturers that will produce similar results.
If you do not own a set of neutral density filters yet, then a good strategy will be to buy them gradually over a period of time, as they are not necessarily cheap! Start with an ND4, or even 2 ND4 filters. By stacking more than one filter, you will already have a good start for waterfalls and streams.
Rule number one is, the faster the flow of the water, the faster your shutter speed can be. This sounds obvious, but is not always so obvious. Look out for rapids, rocks and tree trunks that will disturb the normal flow of the water, as they normally slow down the water before the obstacle, and accelerate the flow below the obstacle.
Some generalisations will be:
The waterfall photo called "Langkloof Waterfall" was taken just outside Barkly East, at one of the spots we will visit during our workshop. There are two waterfalls within 500 metres from one another! This photo was taken without an ND filter at 1 second exposure time.
The photo called "Lazy afternoon" was taken at the picnic spot on the loop beyond Joubert Pass near Lady Grey. The photo was taken about 100 metres above the waterfall. Because of the slow moving water above the waterfall, I used my 10 stop ND filter to achieve a shutter speed of 160 seconds.
"Autumn Reflections" was taken on the road between Barkly East and Dortrecht with an 8ND filter. The exposure time is 10 seconds.
On our Photoparadise workshops we visit a number of streams and waterfalls and I think it is good to share this knowledge beforehand.
(If you have read up to here and did not click on a photo yet, do so to see them in larger format and also to browse through the rest of this gallery)