Most cameras have a default maximum shutter speed of 30 seconds, so I guess the range of shutter speeds from about 1/8000 secs to 30 secs must be classed as the normal exposure range. By that reckoning any shutter speed longer than 30 seconds would count as a long exposure, but, for the purpose of this blog, I’m going to count anything longer than 1 second.
Why, though, would anyone ever need to open the shutter for longer than 1 second? One answer would be to take photographs in low light conditions where. Alternatively, say that you want to use a wide aperture in bright sunlight eg to blur the background behind a shrub that you’re photographing in your garden. In order to avoid the photo being over exposed you could use a neutral density filter (ND filter) to reduce the light entering the camera. Another would be to take photographs to smooth out movement – for example waterfalls, waves or clouds.
Compare this shot at Cleveleys beach, Lancashire with today’s featured photo in which wave motion has been smoothed to focus attention on the rocks. I took the photo on the left at 1/200 of a second but the featured photo at 8 seconds using a 9 stop filter and an aperture half a stop smaller.
I took this shot, mid morning on a bright day with a 10 stop ND filter. My shutter speed was 30 seconds at an aperture of f/8 and ISO 100.
This image was taken within minutes of the one above but the shutter speed was 1/60 secs at the same aperture and ISO. Notice how the movement of the water in the stream was blurred by using a filter.
I won’t be able to explain even the basics in a single blog post, so I’ll spread it out over a few days. Today, I’ll just show a couple of examples of long exposure. Tomorrow, I’ll say something about the various types of filter that photographers use. Then I’ll post a blog about calculating shutter speed for using different strengths of filter. Finally, probably, I’ll go into how to use filters.
Having said all that about filters, in low light conditions you won’t need them normally, your main equipment other than your camera will be a tripod to enable you to take a stable, steady shot.
For this photo of Liverpool by night I used a tripod but I didn’t need a filter. My settings were shutter speed 6 seconds, aperture f/8, ISO 100 and focal length 23 mm. Because I used a tripod I set the image stabilisation to off. Other than that, the effort was simply waiting until all the drivers were using their lights and that there were enough of them moving quickly between two sets of traffic lights.
I hope that these examples may inspire you to look at this blog tomorrow to learn more about the various types of filter.
Enjoy your day.