Photography News Issue 30

Photography News Issue 30 absolutephoto.com

Technique 52

1/125sec at f/11, ISO 100

How to get startedwith long exposures

There are lots of reasons why some long exposures work and some don’t, and many of them come down to subject choice, composition, length of exposure and timing, as discussed in the main text. Outside of those factors, if you get to grips with the basics of shooting long exposures with a neutral density filter you’ll be assured that your picture is at least sharp and well exposed. Here’s how...

1. Set upandmeter Set the camera on your tripod, focus where desired and frame up the shot. In aperture- priority mode (A or Av), dial in the f/number you want to use, depending on the depth-of-field desired, for instance f/11. Set the ISO to a low level, like 100 or 200 and take a look at the resulting shutter speed. For example, let’s say it’s 1/4sec.

2. Switch tobulbmodeand fit theND Now turn the mode to bulb (B). On some cameras there’s no B so you’ll find bulb mode by going to shutter-priority (S or Tv) or manual (M), and then pushing the speed past the 30secs. The previous aperture and ISO should be carried over automatically, but if not, dial them in again. Check focus and framing again and then switch to manual focus to make sure there is no focus shift. Fit your neutral density long exposure filter.

3. Calculating theexposure To get the right shutter speed, take the metered value and adjust it by the strength of the ND filter, which is given in ‘stops’. So, if you’re using a three-stop filter (ND 0.9), double the length of the shutter speed three times; 1/4sec becomes 1/2sec, then 1sec, and finally 2secs. If you’re using a ten- stop filter, it would be four minutes (from 1/4sec to 240secs)*. Make life easier with a smartphone app like Longtime Pro Exposure Calculator.

4. Long-exposureNR Most cameras have a long-exposure noise- reduction (NR) function. This records a second, ‘dark’ frame after the first – usually for the same time – to remove digital noise caused by keeping the sensor charged for a long period. This mode slows down your shooting, so if you’re shooting for several minutes, turn it off. If you’re shooting Raw, NR might not have any effect anyway.

45secs at f/11, ISO 100

5. Shoot and time theexposure During a long exposure it’s necessary to cover the viewfinder eyepiece to stop light entering camera and flaring off the filter and/or overexposing the image. So cover the eyepiece either with your hand, a cap or the built-in blind. Finally, use a remote release so that you don’t jog the camera, activate the shutter. Time the long exposure with your watch, phone or the release itself, and close the shutter when the desired time has elapsed.

*The longer the exposure, the less likely a simple calculation is to be accurate as very strong filters aren’t as easy to judge and more likely to underexpose. Therefore it’s a good idea to shoot in Raw, just in case. Also, the light may change during the time the shutter is open, so if the scene becomes darker, add some time; if it gets lighter, do the opposite.

Above One of the main reasons for using a long exposure is to simplify a scene and avoid a clutter of competing textures, as seen in the top image of Craster harbour, Northumberland shot at 1/125sec. In the bottom image, at 45 seconds, and with the waves blurred, the shapes and details of the harbour wall and the rocks are more easily enjoyed.