Water and long exposure

Learning goal

On a shore, you will be able to show the same sea with frozen droplets, with white lines receding between the rocks, or as a surface flat like fog, and decide which of these three characters to choose according to what the frame wants to tell. By watching the pattern of waves coming in and receding, you will find when to press the shutter, and especially time a short exposure of about a second to the moment the water draws back. You will notice the color cast a dark ND filter leaves in the frame and correct the white balance. On a rocky shore you will take the sea's power into account and protect your lens against salt spray. If there is a person in the frame, you will know how to ask them to hold still in a long exposure and how to bring back on their skin the color the filter shifted.

The question

At the weekend your friend goes to a rocky shore. Waves crash against the rocks and foam; in every frame they shoot with a fast shutter speed there are droplets hanging in the air and sharp foam. The frames are strong but they all look alike. In their mind is a photo shot on the same shore: the rocks sharp, but the sea soft, flat and white, as if a fog had settled between the rocks. The ND filter with almost black glass they bought last month is still in its box. How does the sea come to look like fog?

Context

In the first exposure lessons you saw that a short shutter speed freezes the moment, while a lengthening time softens water and makes it flow (Lesson 8.5). In the long exposure lesson you worked out how much time different movements need to reach the wanted look, and converting an ND filter's stops into shutter speed (Lesson 22.1). In the filters section, too, you once tried mounting a dark ND on a sunny coastal rock and turning the waves milk white (Lesson 13.3).

This lesson adds deciding in the field on top of those calculations. The sea is different from a stream or a waterfall: it doesn't flow constantly, it comes in and recedes. The same exposure time gives a very different frame depending on which moment of the wave it starts at. That is why at sea you choose not only the time but also the timing. What's more, a long exposure is the result of a decision; a frozen wave and a fog-like sea are both honest images of the same shore.

Simple explanation

What decides the water's character?

The same wave takes on three different characters depending on the shutter speed. At roughly 1/500 and shorter, foam and droplets freeze in the air; the sea looks muscular, exuberant, brittle. Between a few tenths of a second and one or two seconds, water carries its movement as a trace; the receding wave draws white lines between the rocks, the sea is both moving and readable. At thirty seconds and longer, thousands of waves pile on top of each other and erase each other; the sea loses its texture and turns into a flat, smooth surface, and in the distance into a haze blending with the horizon.

These times aren't exact; the size of the waves, the speed of the water and your distance to the shore change the result. Which one is chosen, on the other hand, isn't a question of right and wrong. Frozen droplets tell the sea's power, receding lines its movement, a flat surface its stillness. The rocks and the horizon stay the same in all three; what changes is the relationship the viewer builds with the sea.

When do you press the shutter?

Wave rhythm is the repeating pattern of waves coming in and receding on a shore. Waves are often not equal; a few small waves can be followed by a series of bigger ones. Just watching for a few minutes before setting up the camera lets you see this pattern: when the water climbs over the rocks, when it stops and when it draws back.

A receding wave trail is the white lines that water leaves in a short exposure as it flows between rocks and pebbles while a wave draws back. To catch these trails you time the exposure to the moment the water begins to draw back; you press not when the wave hits the shore, but when it stops and starts to turn back. A time between half a second and one second is often a good start. Pressing at the same moment over several waves and comparing the frames shows which timing gives the cleanest lines. In long times, on the other hand, timing loses its importance, because the exposure covers many waves.

What do the filter and the sea change?

A filter color cast is the slight color deviation a dark ND filter leaves in the frame. Many dark filters, especially cheap ones, can add a warm, magenta or blue tone to the frame. Leaving the white balance on auto doesn't always correct this. Mounting the filter and shooting a gray card or a white sheet of paper in the same light makes it easier to bring the whole series to the right color afterward.

This cast is noticed most on human skin. Light skin can shift toward pink or gray, dark skin from brown toward a purplish or leaden tone; in both cases the person loses their own color. In a long exposure it is also hard for someone to stand completely still; they are asked to lean against a rock and stay calm, or their face is taken from a separate, short frame. On a rocky shore you never turn your back to the sea, stay away from wet, mossy rocks, and see your escape route in advance against an unexpected big wave. Salt spray leaves a thin layer on the front of the lens; wiping it with a dry cloth every few frames keeps the frame from turning hazy.

Visual evidence

First your friend watches for a few minutes. Five or six small waves are followed by three bigger waves. They set the tripod on a dry rock a few steps back from the shore.

At 1/1000, when a big wave hits the rock, the foam freezes in the air. Then they mount the ND and raise the time to one second. In the frame they press when the wave hits the rock, everything is a white blotch; when they press at the moment the water begins to draw back, thin white lines run down between the rocks toward the sea.

As the sun sets they mount the darkest filter and shoot thirty seconds. The sea is flat and white, the rocks sharp, the horizon blended into haze. The frame comes out too magenta; they correct the color with the gray card they shot with the filter beforehand. Their friend sitting leaning against a rock, a young dark-skinned man, looked leaden before the correction; after the correction his skin is in its own warm brown. Because his face moved slightly, they take him from a short frame shot from the same spot.

Common mistakes

Summary

The shutter speed decides the water's character: a short time freezes the wave, half a second to one second turns the receding water into white lines, thirty seconds and more turns the sea into a surface flat like fog; which one is chosen depends on what the frame wants to tell. In short exposures, the shutter is timed according to the wave rhythm to the moment the water draws back; a dark filter's color cast is corrected with a gray card so that the skin of the person in the frame stays in its own color, and on the shore you never turn your back to the sea.

Mini assignment

In this assignment you will shoot three different characters at the same water's edge.

1. On a shore or by a wavy lake, watch for a few minutes and note the pattern of waves coming in and receding.
2. From a tripod, shoot the same framing first with a short shutter speed, then with a one-second exposure starting at the moment the water draws back, and last, if you have one, with a dark filter for thirty seconds.
3. Shoot a gray card or white paper with the filter mounted, correct the colors accordingly and, if someone is in the frame, check whether their skin appears in its own color.

Check yourself

• In the short exposures, are the receding trails distinct, or did they turn into a white blotch?
• Does each of the three frames show the sea with a different character?
• Was the filter's color cast corrected, is the person's skin natural?

Glossary

Mini quiz

1. What time is needed for the sea to look flat like fog?

• A) 1/1000
• B) 1/125
• C) Thirty seconds and longer
• D) 1/30

2. When do you press the shutter to catch receding trails?

• A) At the moment the wave hits the rock
• B) At the moment the water begins to draw back
• C) When the sea has stopped completely
• D) At a random moment

3. How is a dark ND filter's color cast corrected?

• A) By wiping the lens before mounting the filter
• B) By opening the aperture
• C) By shortening the shutter speed
• D) By shooting a gray card with the filter mounted and adjusting the series accordingly

4. Why don't you turn your back to the sea on a rocky shore?

• A) Because an unexpected big wave can take the photographer and the camera
• B) Because the light comes from behind
• C) Because the waves are loud
• D) Because the sky will darken

Answers

1. C — A long time piles thousands of waves on top of each other, the texture disappears and the surface flattens.
2. B — Receding water leaves white lines as it flows between the rocks, while the moment of impact gives a white blotch.
3. D — The gray card shows the tone the filter added, and the whole series comes to the right color with the same correction.
4. A — Waves aren't equal, and a big wave arriving in between can knock someone at the tip of a rock off their feet.

Summary card

• The time chooses the water's character: frozen, lined or fog-like.
• Watch first; find the wave rhythm.
• Time the short exposure to the moment the water draws back.
• Shoot a gray card with the dark filter; return the skin to its own color.
• Don't turn your back to the sea, stand back, wipe the salt off the lens.

Bridge to the next lesson

After the thirty-second frame, as your friend packs up, dark, leaden clouds come in from the north; the wind sharpens, the first drops fall. They want to put the camera in the bag and run to the car. Yet the last light seeping between the clouds lights up the opposite rocks like a stage. Why is a storm an opportunity? The next lesson takes up what fog, rain and a dark sky add to a landscape, and how to protect both yourself and your camera in bad weather.