Photography News | Issue 54 | photographynews.co.uk Technique 47 Camera School Here we lift the lid on all things camera related, showing how to get better results from your CSC or DSLR, and providing all the info you don’t find in the manual. So, stick with us and you’ll soon be wielding your camera like a pro. This month, what long exposures are and how to produce them with your camera
Words & pictures by Kingsley Singleton
2 second exposure
1/20sec exposure
What are long exposures? And what separates them from regular photography? One of the most obvious things is that long exposures illustrate an extended period of time. In that sense, long exposures usually (though not always) show movement as a blur. It could be the motion of people, clouds, water, even the shadows cast by the sun… whatever it is, a long exposure will record it. The ‘long’ part of the name comes from the shutter speed employed to achieve this, and while there’s no set shutter speed that technically defines a picture as a long exposure, it’s helpful to think of them as those in the seconds, rather than fractions of seconds. How to achieve a long exposure As your camera meters a scene, it decides how much light is required to get a good exposure. The amount of time taken to record this light is the shutter speed, and it’s influenced not only by the brightness of the scene, but also by the two other variables of the exposure triangle; aperture and ISO. Small apertures record little light compared to large ones, and low ISOs little light compared to high ones, so if you set a small aperture, like f/16, and a low ISO, like 100, the shutter speed needs to lengthen to compensate or you’ll underexpose. Depending on the brightness of the subject, this may not, on its own, provide a long enough shutter speed for your purposes, but it pushes the shutter speed in the right direction. Shooting in aperture-priority (A or Av), if you set a small aperture and low ISO, the shutter speed will lengthen as calculated by the camera; this is the simplestway to control a long exposure, as there’s very little chance of over or underexposing. In shutter-priority (S or Tv), you can dial in the actual shutter speed
1/4sec exposure
1/2sec exposure
still throughout the exposure will keep the motionless parts of the scene, like rocks around a river, sharp and static. If you want the latter effect, mount your camera on a tripod before you shoot, and make sure it’snot likely tobenudgedor slipduring the exposure. If youwant to try the former, consider a long exposure technique called intentional cameramovement (ICM), somethingwe'll cover in detail in an upcoming Camera School . NEXTMONTH LEARN MORE ABOUT LONG-EXPOSURE TECHNIQUES, INCLUDING USING ND FILTERS. Above At slow shutter speeds and with your camera still, moving parts of a scene, such as water, appear as a blur, while still parts are sharp. The amount of blur depends on the shutter speed and the speed of movement.
youwant and the aperturewill close to compensate, but it may not be able to close enough due to the physical restrictions of the lens’s design. In Manual (M) you have
full control of all three, and in Bulb (B), you can keep the shutter open for as long as you like, though more calculation is required.
measured in exposure stops. Every stop of darkening will double the length of your shutter speed; so a one-stop filter will turn 1/8sec into 1/4sec, but a five-stop filter will take you
downadarkroadwill showupas streaksof light during a long exposure, but a person wearing dark clothingmight become invisible. Part of the art of using long exposures is in choosing the right speed to show what you wanted in the scene. You may want to show movement inwater, andwhere shooting at 2secs will show the flow of a tide, 20secs might turn it into a static looking mist; conversely, while shooting cars on a road, while 20secs would give you long streaks of light, 2secs wouldmake the same streaks short and stubby. Keep it steady Whatever time of day you shoot, or long shutter speed you use, whether you choose to secure the camera’s position or not is important. If you shoot long exposures handheld, you’ll get nothing but blur, which can be very effective in an abstractway. Conversely, keeping the camera
Lowering the light To create long exposures, the other contributing factor is the available light. Shooting around dawn or dusk when light levels are lower than the middle of the day will naturally lead to longer exposures. So while in the middle of a sunny day, an aperture of f/16 and an ISO of 100, might give you a shutter speed of 1/100sec, at dusk, when the sun has left the sky, this will fall dramatically, becoming seconds, or evenminutes. To force the issue you can artificially lower the amount of available light, using neutral density (ND) filters. These cut the amount of light entering the camera by an amount
from 1/8sec to 4secs.
How long do you need? Typically, at slow shutter speeds, anything moving in the scene during the exposure will appearasablur,andtheamountofblurdepends on two things; the speed of the subject and the length of time the shutter is open. Therefore, assuming its rate of movement is constant, a subject will take on twice as much motion blur at 2secs as it does at 1sec. Howmuchmovement is visible also depends on the brightness of the subject versus the rest of the scene. For instance, car headlightsmoving
Powered by FlippingBook