Creating long exposures

A tripod was required to capture this 13-second exposure of an urban beachfront. The long exposure blurs all water movement, imparting a creamy appearance to breaking waves. City lighting adds a warm tone that harmonises with the colours of the fireworks. A 16mm wide angle lens was used at f/10 on a ‘full frame’ DSLR camera for adequate depth of field. The ISO setting was 800. ©iStockphoto.com/Matt Stansfield.

In this feature we will look at the subjects you can photograph and the shooting techniques you should use when you use the essential piece of equipment required for long exposures: a tripod. Mounting your camera on a tripod enables you to use much slower shutter speeds than are possible with a hand-held camera ““ even if supported by stabilisation.

The other important parameter is the ability to adjust shutter speeds on your camera and use exposures of at least 30 seconds, preferably longer. Both issues will be addressed in this feature.

Camera Requirements

No particular lenses are needed for long exposure photography and it doesn’t matter whether your camera has interchangeable lenses. The two most important requirements are the ability to capture exposures longer than one minute and the ability to trigger the exposure without jiggling the camera.

Most cameras come with self-timers that delay the start of exposures by two, five or 10 seconds, enabling the camera to stabilise before the shutter opens. The longer the delay, the more likely the camera is to be stable.

An alternative is a remote control, which can be either wireless or wired. Wireless remotes are preferable as they have no physical contact with the camera, whereas a cable may flap about. A locking remote is essential for really long exposures.

The best cameras will include B (Bulb) and, maybe, T (Time) settings in their exposure controls. Traditionally, the B setting kept the shutter open while the shutter button (or remote trigger) was held down, while the T setting opened the shutter with the first press of the trigger and closed it with the second.

However, many camera manufacturers have introduced variations of these controls. Some limit the exposure length for one or other of them, often restricting exposures to less than 30 minutes, which isn’t ideal for shooting star trails. Check your camera’s manual to find out what limitations apply.

What to Photograph

Many different subjects can be recorded with long exposures; you must simply decide whether you want to record the subject itself (with everything sharp) or motion with respect to a stationary subject. If it’s the former, you will be looking for interesting lighting. For the latter, the interest will be on blurred effects.

‘Around the campfire’ shots are popular on camping trips. But don’t expect people to keep still for more than a couple of seconds. This 10-second exposure at ISO 400, taken with a small-sensor digicam, shows some blurring caused by subject movement as well as traces of high-ISO image noise due to the small image sensor.

Popular subjects containing movement include star trails and light trails (from passing traffic), blurred clouds or waving grass in landscapes and softening water in seascapes, shots of creeks or rivers or creating ethereal effects with waterfalls. In built-up environments, long exposures can be used to make crowds on the street disappear or produce ghostlike appearances of passers-by.

This 10-minute exposure showing star trails would have been impossible without a tripod. It was taken with a 10mm focal length lens on an APS-C DSLR camera using ISO 100 to minimise noise with an aperture of f/5.6.

It helps to scout out locations beforehand so you have a good idea of where to set up your tripod. Great lighting can be fleeting and you want to be ready to shoot when it appears.

Check the weather before leaving home so you know if wet and/or windy conditions are forecast and when they are likely to occur. You may want to use them in photographs ““ or avoid them. Either way, it’s worth knowing what to expect. Check the tides if you are shooting seascapes.

Camera Settings

First, turn off the flash and select the Manual or Bulb shooting mode. Set up the camera on a tripod and focus on the area you wish to have sharp. Smaller lens apertures allow longer exposure times and capture the widest depth of field. They are ideal for scenes photographed with wide-angle lenses.

Exposures needn’t be long for capturing shots of firework displays ““ but they are generally longer than you can hand-hold the camera, even with the aid of stabilisation. A tripod was used for this 1.6-second exposure with ISO 1600 at f/16 using the Manual shooting mode.

Tripod-mounting your camera enables you to use low sensitivity settings to minimise image noise. In-camera long-exposure noise-reduction will soften the image slightly but should reduce the incidence of ‘salt-and-pepper’ noise (see the section on image noise in Chapter 1).

Metering long exposures can be tricky since some cameras’ metering systems won’t work in very low light levels and subject brightness ranges are often wider than the sensor can handle. When that’s the case, you must estimate the required exposure by trial and error and be prepared to take several shots at different exposure levels. If the camera has been tripod-mounted, these shots can be combined to produce a correctly exposed picture using image editing software.

An example of a subject with a brightness range that exceeds the capabilities of the camera’s sensor. To record the sky correctly, an exposure of 20 seconds was needed with an ISO of 200. This caused the foreground to be under-exposed to such a degree that it is rendered as a silhouette and no usable details can be extracted with post-capture adjustments.

Unless your camera includes special settings for recording star trails, exposures of at least 30 minutes will be needed for the lines to be of adequate length. Longer exposures, often several hours long, are required for the most impressive images.

Vehicle head and tail light trails usually require much shorter exposures. In a busy location, a 30-second exposure should deliver a worthwhile effect. Set up your tripod where it overlooks the area and use an aperture of f/11 or smaller for maximum depth of field.

Blurred water shots can be achieved with exposures of between five and 30 seconds ““ or several minutes. The longer the exposure the more misty the water appears.

Photographs containing the moon can be difficult to record due to the differences in brightness between the moon and the rest of the subject. The best results are achieved when the moon is close to the horizon, where its brightness is attenuated by the atmosphere, particularly when there is some dust in the air or the sky is partly cloudy.

Sydney Cove on New Year’s Eve, photographed with a 75mm lens on ‘full frame’ DSLR camera. The eight-second exposure blurs the movements of boats in the bay. The exposure was made at ISO 800 with an aperture of f/8.

Painting with Light

Sometimes the light is too bright for the main subject to be rendered as anything other than a silhouette. In such situations, it’s easy to add light to the subject without resorting to flash by ‘painting’ it with light from a torch or LED lamp.

Light painting requires very long exposures, usually at least 30 seconds, as you need time to play the light across the face of the subject. Move the light carefully, aiming to give an even exposure.

The best technique is to sweep from one side of the subject to the other, ensuring the light covers it from top to bottom. If you try to scan the object with several sweeps, overlapping areas will get more light, which can produce banding.

Children with sparklers on a dark night can ‘draw’ patterns for your camera (and have fun at the same time). A 15-second exposure with a 12mm lens on a M4/3 camera, ISO 100, f/5.6. Exposure compensation of -1.0EV was applied to prevent the sparklers from being unnaturally bright.

A variation of this technique is light drawing, which involves shining a light source at the camera or onto a darkened wall and ‘drawing’ a picture by moving the source rapidly. Shutter speeds of three or four seconds can be long enough for simple drawings. Sources of light can include pencil torches, candles, matches, sparklers, lighter flints and glowsticks.

Shooting Tips

While shots involving light drawing rely for their appeal on the shapes, colours and patterns created, most other shots gain impact by the contrast between stationary elements in the scene and the ways in which moving subjects are recorded. Try to include a stationary element, such as a tree, a building, the edges of a road or even the dashboard of a car (when the shot shows moving scenery outside the car).

A two-second exposure of a carousel in motion creates a strong impression of speed. Taken with the Samsung NX1 camera at ISO 100 with a focal length of 16 mm and aperture of f/22 to maximise depth of field. © Yang Ji Eul.

When capturing a light trail, use shutter priority mode and start with the camera’s lowest ISO setting and an exposure of two to five seconds. Check the result and if the trail is too short and/or the scene is under-exposed, double the exposure time. Continue to shoot and check, increasing exposure times until you have the effect you want.

Subjects in which water is the main focus are usually best photographed just after the sun has set. This ensures there is enough light remaining in the sky for reflections in still water to be sharp and clear, while also retaining the afterglow of sunset.

Choosing a Tripod

Choosing a tripod depends on how much weight you can carry and your preferences for adjusting the head that supports the camera. If you can set up your gear close to a car (or other vehicle) you have the luxury of being able to use a heavy, solid tripod. For really long exposures (several minutes to an hour or more) the sturdier the tripod, the better.

Travellers and photographers who have to carry their equipment for a kilometre or more will probably prefer a light tripod. This forces a choice between weight, stability and cost and may limit the height at which the camera can be placed. Carbon fibre tripods provide the best combination of light weight and high stability. But they usually cost two to four times as much as a similar aluminium tripod.

A Sirui T-1204X tripod + K-10X head. (Image supplied by Rene Vogelzang, equipment from Mainline Photographics.)

The Sirui T-1204X tripod and head shown above in use with a Sony A7R and Voigtlander 15mm f/4.5 lens for a night shot at Sydney’s Darling Harbour. ( © Rene Vogelzang, www.renevogelzang.com.)

Cheaper tripods may be usable for exposures less than 30 seconds, as long as you’re shooting in windless conditions. But make sure their legs are well spread and the feet rest on stable ground. If there’s a breeze, don’t extend the central column and attach a heavy weight below the mount to counteract possible movements.

There are several types of tripod heads: pan-tilt heads and ball heads are the most popular but geared heads provide more precise adjustments and are favoured by architectural photographers for this reason. Ball heads are more compact than pan-tilt heads, but the latter are easier to adjust.

Most photographers prefer heads with quick-release plates that enable the camera to be attached and removed quickly. The so-called Arca type quick-release plates are the most popular since they fit tripods from most brands.

 

Excerpt from  Low Light Photography  pocket guide