N-Photo - The Nikon Magazine - UK (2019-12)

Calculate a long exposure

1

Take a test shot
If you want to shoot with a very long
exposure to blur clouds like this, then it can be
helpful to begin with a quick test shot using a
very high ISO. Here we used Aperture Priority at
f/16, ISO6400 and 1.3 secs. We can use this as a
base to work out an equivalent long exposure for
our photograph and go from there.

2

Use a calculator

An app like PhotoPills is helpful for

calculating equivalent exposures. Here we lower

the ISO to 100, which increases the shutter speed

to 1 minute 23 seconds. Then, to increase the

time even more, we factor in a three-stop ND

filter, resulting in an exposure length of exactly

11 minutes 6 seconds.

3

Time the shot

Now we lock open the shutter with the

cable release to take the shot and we use a

stopwatch to keep an eye on the time. When

shutter speeds last for tens of minutes a few

seconds here or there will have minimal effect on

the exposure, so you don’t have to be exact with

your timing, but it pays to keep an eye on it.

Cloud movement

and blur

WHAT’S THE CORRECT

SHUTTER SPEED TO BLUR

SLOW-MOVING CLOUDS?

The amount of blur in the sky here

depends on the speed of the clouds

as well as the length of the exposure.

In windy conditions, fast-moving

clouds may blur nicely after a minute

or so, whereas in calm conditions,

like the evening we shot on, it’s only

possible to achieve motion blur by

pushing the shutter speed beyond

several minutes.

You can see the difference here

between exposure times of eight, 20,

75 and 780 seconds. In the shorter

exposure detail is retained in the

clouds, while in the longer exposure

it’s blurred to attractive streaks. The

other factor to consider in scenes like

this is the balance of light on the

building and the sky. By waiting until

near-darkness, the windmill

contrasts more boldly with the

twilight sky – timing is everything.

CREATIVE TECHNIQUES

8 secs

75 secs

20 secs

780 secs