Long Exposure Photography: Settings, Gear and Techniques

Long exposure photography means leaving the shutter open on purpose, for a fraction of a second up to minutes or hours, so that movement is recorded over time instead of frozen. The camera stays still on a tripod, so rocks, buildings and trees stay sharp, while water, clouds, car lights and stars turn into smooth sheets and streaks that the eye never sees.

The snowy creek above is a 30 second exposure. In that time the water poured over every rock thousands of times, and the frame recorded all of it at once as a soft white flow. Everything on this page follows from one idea, that a long exposure is an average of everything that happened in front of the lens while the shutter was open. Once that clicks, you can predict what water, clouds, crowds and headlights will do before you press the button, and work out how dark the light, or the filter, has to be to get there.

What a long exposure records: an average over time

Each point on the sensor keeps collecting light for as long as the shutter is open. What ends up in the file at that point is the total of whatever was in front of it, weighted by how long it stayed there. A rock that never moves sends the same light the whole time, so it comes out sharp. A stream sends light from water that is in a different place every instant, so the spot records the average of all those positions, which is why rippled water becomes smooth.

Click the photo you think used the longer exposure:

Which photo used a longer exposure?

A B

The same averaging explains the effects that look like tricks. A person who walks past a spot covers it for only a moment and contributes almost nothing to that spot’s total, so they vanish. Someone who stops for a while leaves a see-through ghost. A car disappears, but its headlights do not, because a light that is far brighter than the road can dominate a spot even in the brief moment it passes.

Push the averaging far enough and the subject disappears entirely. The longest exposure most people have seen is in Hiroshi Sugimoto‘s Theaters series: he left the shutter open for the whole length of a film, so the screen burns to pure white and its light alone draws the empty cinema. Every scene of the film is in that white rectangle, averaged into nothing.

One thing a long exposure does not do is make the picture brighter. A correct exposure is a fixed amount of light. If you hold the shutter open 64 times longer, you have to let 64 times less light in per second, by waiting for dimmer light, using a smaller aperture and a lower ISO, or putting a dark filter on the lens. That is the whole practical problem of long exposure, and it is covered below.

How long is long? Shutter speeds for each subject

There is no fixed line where a normal exposure becomes a long one. A common shorthand is “anything slower than you can handhold”, but that limit moves with focal length and stabilization (see the hand-holding rule). A more useful definition: an exposure is long when you chose it so that something moves a visible distance while the shutter is open. What counts as a long time depends entirely on how fast the subject moves and how big it is in the frame.

Those ranges come from simple distance. The table shows how far typical subjects travel during different exposures. Compare each distance with the size of the thing that is moving: once it moves farther than its own size, it is a smear, not a shape.

Subject (speed)	1/500 s	1/15 s	1/2 s	4 s	30 s	4 min
Falling water (3 m/s)	6 mm	20 cm	1.5 m	12 m	90 m	720 m
Person walking (1.4 m/s)	3 mm	9 cm	0.7 m	5.6 m	42 m	336 m
Car in town (50 km/h)	3 cm	93 cm	6.9 m	56 m	417 m	3.3 km
Cloud in a 10 m/s wind	2 cm	67 cm	5 m	40 m	300 m	2.4 km

Read across the rows and the subject ranges make sense. Falling water moves 1.5 m in half a second, far more than the size of a ripple or a drop, so a waterfall goes soft at speeds that are short by long exposure standards. A 4.5 m car moves 56 m in 4 seconds, more than 12 times its own length, so its body spreads too thin to see while its lights draw lines. A cloud hundreds of metres across moves only 40 m in 4 seconds and barely softens; it takes minutes, and a strong wind, before clouds become streaks. Stars move with the Earth’s rotation, about 15 degrees of sky per hour, so a 30 second frame moves them only an eighth of a degree, while an hour turns them through 15 degrees.

Water: longer is not always better

Water changes character as the exposure grows. Around 1/8 to 1 second, fast water keeps visible streaks and shows its direction and energy. From about 1 to 4 seconds a waterfall or stream turns into the familiar silky veil. At 30 seconds and beyond, waves on a lake or the sea stop being waves at all and the surface becomes flat and misty, as in a seascape shot for minutes. None of these is the correct look; pick the one that says what you want to say about the water, and shoot a few lengths to compare.

The camera simulator lets you find the shutter speed where water turns to silk, while keeping the rocks sharp and the exposure right:

Want the other challenges? The full camera simulator has all 21, across eight scenes.

Getting a long shutter speed: take light away

Because the exposure has to stay the same, every extra stop of time has to be paid for with a stop less light. A stop is a doubling, so 1 second needs half the light of 1/2 second, and 64 seconds needs 1/64 the light of 1 second. You have four ways to take light away, and you usually use them in this order:

1. Lower the ISO to the camera’s base setting, usually ISO 100. This also gives the cleanest file.
2. Close the aperture to about f/11 or f/16. Going much smaller than f/16 softens the whole frame through diffraction, so it is a poor way to buy time.
3. Wait for less light. Overcast skies, open shade, the dusk after sunset and night all give you longer exposures for free.
4. Add a neutral density (ND) filter, a dark grey filter that cuts light evenly across colors. A polarizing filter also takes away about 1.5 to 2 stops, a small start if it is the only filter you have.

Steps 1 and 2 do not get you far in daylight. By the sunny 16 rule, bright sun at ISO 100 and f/16 needs about 1/100 second. Stopping down to f/22 buys one more stop, 1/50 second, at a visible cost in sharpness, and that is the end of the road without a filter, which is why daytime long exposure is mostly about ND filters, and why dusk is the best place to start.

ND filter arithmetic: stops and multipliers

ND filters are labelled two ways, and mixing them up is the most common source of confusion. One label gives the stops of light the filter removes. The other, the “ND number”, gives the factor by which it multiplies your shutter time. Each stop doubles the time, so the factor is 2 multiplied by itself once per stop:

• 3 stops = 2×2×2 = 8 times longer (sold as ND8)
• 6 stops = 64 times longer (ND64)
• 10 stops = 1,024 times longer (sold as ND1000, rounded)
• 15 stops = 32,768 times longer
• 16 stops = 65,536 times longer

To find your shutter speed with the filter on, meter the scene without it, then multiply the shutter time by the factor. The table below does this for common starting points. Shutter labels on cameras are rounded (1/125 is really 1/128, 1/30 is really 1/32), so a counted-out answer and a multiplied one can differ by a few seconds; that is a fraction of a stop and does not matter.

Metered without a filter	+3 stops (ND8)	+6 stops (ND64)	+10 stops (ND1000)	+15 stops
1/250 s	1/30 s	1/4 s	4 s	2 min 11 s
1/125 s	1/15 s	1/2 s	8 s	4 min 22 s
1/60 s	1/8 s	1 s	17 s	9 min 6 s
1/30 s	1/4 s	2 s	34 s	18 min 12 s
1/15 s	1/2 s	4 s	1 min 8 s	36 min 25 s

Look at the 10-stop column and a popular claim falls apart. A 10-stop filter does not give minutes in bright sun. Sun at ISO 100 and f/11 meters at about 1/200 second, and 1/200 × 1,024 is about 5 seconds: plenty to smooth a river, nowhere near enough to streak clouds or empty a square. In the same light a 15-stop filter gives about 2 minutes 44 seconds, and 16 stops about 5 and a half. Minutes in daylight need a 15 or 16-stop filter, two filters stacked, heavy overcast, or the light after sunset.

The exposure calculator does this multiplication for any filter and starting speed. To practise the whole sequence, fit a filter of 6 stops or more in the simulator’s waterfall scene and get a correctly exposed frame of 2 seconds or longer:

Choosing between a 6, 10 or 15-stop filter, or wondering about screw-in versus square? The ND filter guide covers strengths, types and color casts.

Clouds need the most time of all common subjects because they are huge and far away. In a minute, a cloud in a steady wind moves a few hundred metres, enough to stretch it into long streaks. On a calm day the same minute shows almost nothing, so check the wind before you plan a cloud streak.

Night and dusk: the dark is the filter

After sunset you need no filter at all. The light falls by many stops within half an hour of sunset, so exposures of several seconds at f/8 and ISO 100 arrive on their own, and a lit city at night often lands between 5 and 30 seconds. This is the easiest place to learn, because mistakes cost nothing and you can see each result immediately. The best window is often blue hour, when the sky still holds color and detail while street and car lights are already bright; a few minutes later the sky goes black and the lights are all that is left.

In real darkness the meter often gives up, and a guess at 2 minutes wastes 2 minutes. Use a high-ISO test frame instead. Raise the ISO 6 stops, from 100 to 6400, and find the shutter speed that looks right, say 2 seconds. Then go back to ISO 100 and multiply the time by 64: 2 seconds becomes 128 seconds, about 2 minutes 8 seconds. Check the histogram of the test frame, not just the screen, which looks brighter than it is in the dark.

Autofocus also struggles in the dark. Magnify live view on a bright light or star and focus by hand, or light a nearby subject with a flashlight, focus on it, and switch to manual focus before you turn the flashlight off.

A long exposure, step by step

The order matters, because once a dark filter is on you can barely see through it. This sequence works for any subject:

1. Set up the tripod solidly. Extend the thickest leg sections first and leave the center column down; a raised column is the wobbliest part of most tripods. See how to use a tripod.
2. Compose and focus without the filter. Focus with autofocus or by eye in live view, then switch the lens or camera to manual focus so it cannot hunt later.
3. Meter without the filter in manual mode at your chosen ISO and aperture, and note the shutter speed.
4. Fit the filter without turning the focus ring, and work out the new time from the table or the calculator.
5. Cover light paths. On a camera with an optical viewfinder, close the eyepiece shutter or cover it, because light entering there can reach the sensor and fog long frames. Mirrorless cameras with electronic viewfinders do not have this path. With square filters, make sure the holder’s seal sits flat against the lens.
6. Fire without touching the camera, with a remote release, a phone app or the 2 second self-timer. For anything over the longest timed speed (usually 30 seconds) use bulb mode with a locking remote or the camera’s built-in bulb timer.
7. Check the histogram and adjust. Too bright or too dark by a stop? Double or halve the time and shoot again.

Settings that matter for long exposures

• File format: shoot RAW. Strong ND filters often add a warm or magenta tint, and RAW lets you correct the white balance without damaging the file.
• ISO: the base setting. It gives the cleanest file and the longest time.
• White balance: set a fixed one, such as daylight or a Kelvin value, rather than auto. Auto can choose differently from frame to frame, which shows when you compare a sequence or stack it.
• Aperture: about f/8 to f/11 for most scenes. Choose it for the depth of field you need first, and buy extra time with the filter rather than with f/22.
• Stabilization: turn image stabilization off on a tripod unless your camera’s manual says its system detects a tripod. A system searching for shake that is not there can add a little of its own.
• Shutter vibration: on a DSLR, mirror lock-up removes the jolt of the mirror; on any camera, an electronic first-curtain shutter removes the jolt of the shutter starting. Both matter most from about 1/30 to 1 second, where a jolt is a large share of the exposure; in a 2 minute frame it is a tiny one.
• Long exposure noise reduction: with LENR on, the camera takes a second, black frame of the same length after each shot and subtracts its hot pixels. It works well on single long frames, especially on warm nights, but it doubles the time per frame (a 4 minute shot ties up the camera for 8). Turn it off when you shoot a sequence for stacking, because it leaves gaps between frames. Another route is to take one frame of the same length with the lens cap on at the end of the session and subtract it from your frames in editing software, which costs one frame’s time instead of doubling every shot.
• Batteries: long frames, and LENR in particular, use more power than normal shooting, and cold cuts a battery’s capacity. Carry a spare in an inside pocket, where it stays warm.

Composing a long exposure: something still, something moving

A long exposure changes what is in the picture, so it changes how you compose. Smoothed water, streaked sky and blurred crowds are soft, even areas with little detail, and a frame made only of them reads as a grey wash. The picture comes from the contrast between sharp and smooth, so anchor it with something that does not move: a rock in the surf, a pier, a building, a tree, a railing.

Then look at the direction of the motion. Water falls, clouds drift with the wind and traffic follows the road, and each will draw lines across the frame. Make those lines agree with the structure of the picture, leading the eye toward the anchor or along the frame, rather than cutting across it. If clouds are moving across a vertical composition, turn the camera, move, or wait for a different sky. Foreground detail matters more than usual, because so much of the rest of the frame will turn soft.

Light trails, star trails, crowds and lightning

Each classic long exposure subject is the averaging idea applied to something different.

Light trails. Cars vanish and their lights stay, for the reason in the diagram near the top. Exposures of 5 to 30 seconds work from a bridge or roadside at dusk or night. Time the shutter to open just as a cluster of traffic enters the frame, so the lines run unbroken from edge to edge. Headlights record white, taillights red.

Want trails that run unbroken through a whole interchange? Light trail photography covers timing, vantage points and stacking several frames.

Star trails. The sky turns about 15 degrees an hour around the celestial poles, so a 1 hour exposure draws each star as a 15 degree arc, and even a whole night gives only part of a circle. Point toward the pole for concentric arcs. In the northern hemisphere the pole sits close to the bright star Polaris; in the southern hemisphere there is no bright star at the pole, so find it from the Southern Cross. Aim east or west instead and the trails become long tilted curves. Many photographers instead shoot hundreds of 20 to 30 second frames with an intervalometer and blend them in software, which gives cleaner files than one frame hours long and survives a passing car or a bumped tripod.

Ready to try the sky? Star trail photography walks through location, settings and stacking.

Crowds. As the diagram shows, people who keep moving vanish from a long frame, but anyone who stops for a significant share of it stays as a ghost. To clear a busy square in daylight you need several minutes, which means a 15-stop filter or more, and even then a seated group will remain. Another route is to shoot 20 to 30 normal frames from a tripod and blend them so each spot keeps the value that appears most often (a median blend). More on both methods in photographing busy landmarks without the crowds.

Waiting for an event. A long exposure can also be a net. Lightning, fireworks and meteors happen faster than you can react, so you open the shutter first and let the event arrive while it is open.

For more on working in the dark, see night photography; for drawing with a flashlight during the exposure, see light painting.

Two other ways to record time: stacking and moving the camera

Stacking short frames. Instead of one long frame, you can shoot a sequence of shorter ones from a tripod, often with an intervalometer, and combine them in software. How you combine them decides the look. An average (mean) blend gives each spot the average of all the frames, the same thing a single long exposure records, so 60 one-second frames averaged look much like one 60-second exposure. A lighten blend keeps the brightest value at each spot, which joins star trails and light trails into continuous lines. A median blend keeps the most common value, which removes people, as in the crowd method above. If each frame is very short, the motion is sampled at separate instants instead of recorded continuously, so it takes many frames before water looks smooth, and fast lights show as dotted lines. In return, stacking needs no strong filter at dusk, keeps noise and hot pixels down, lets you drop a frame spoiled by a bumped tripod or a passing headlight, and leaves you the single frames as well. Making a long exposure from timelapse photos walks through it.

Moving the camera on purpose. Everything above keeps the camera still and lets the subject move. Intentional camera movement (ICM) does the opposite: you move the camera during an exposure of about 1/4 to 2 seconds, so the whole scene smears. A vertical sweep along a stand of trees turns the trunks into streaks of tone; a sideways sweep along a horizon turns sea and sky into bands of color. The results are hard to predict, so shoot many frames and expect to keep few. In daylight you will need a small aperture, base ISO or a light ND filter to get that slow a shutter. Motion blur covers panning and the other ways of using blur on purpose.

Common mistakes in long exposure photography

• Expecting minutes from a 10-stop filter in sun. It gives about 5 seconds at f/11 and ISO 100. Plan on a stronger filter, or shoot when the light is lower.
• Trusting stabilization instead of a tripod. Stabilization can stretch a handheld shot by a few stops, from about 1/60 to perhaps 1/4 second. It cannot hold a camera still for 10 seconds, let alone a minute.
• Turning the exposure compensation dial in manual mode. With a fixed ISO it changes only the meter reading, not the picture. Change the shutter time.
• A frame that is all white. Usually the time was worked out for a filter that is not on, or a stop count went wrong (10 stops is 1,024 times, not 10 times). Check against the table, take a test frame and read the histogram.
• A haze or bright band across the frame. Light got in through an uncovered optical viewfinder or around a filter holder. Cover the eyepiece and seat the holder properly.
• Soft rocks as well as soft water. The camera moved: a raised center column, wind on the tripod, a hand on the camera, or a bridge that shakes when traffic passes. Weigh the tripod down and shield it from the wind.
• A dark X across the sky. A variable ND filter set near its strongest end produces an uneven cross-shaped pattern, worst with wide lenses. Back it off or use a fixed-strength filter.
• A tilted horizon or a fogged filter. In a 4 minute frame you cannot reshoot quickly, so level the tripod before you start, and in cold or humid air check the filter and front element for condensation before each frame.
• Exposures that change from frame to frame. Auto exposure bracketing left on from another shoot shifts the exposure on every frame, and in a long exposure each wrong frame costs minutes before you see it. Turn bracketing off unless you mean to use it.
• Dust spots in the sky. At f/16 and smaller, specks of dust on the sensor show as dark blobs in smooth areas. Shoot a plain sky at your working aperture to check, and clean the sensor or retouch them out.
• Going longer by habit. Past a point water loses all its texture and becomes a blank surface. Shoot 1/4, 1 and 4 seconds and compare before deciding.
• Thinking a phone’s long exposure mode is the same thing. It blends many short frames rather than holding one long one. The look is similar, but fast lights can show gaps between frames.

Only have a phone with you? Phone long exposure shows how to blur water, lights and crowds with the built-in modes.

Try this: one stream, five shutter speeds

Find moving water in dim light, such as a stream, a fountain or waves breaking on a shore, in the dusk after sunset or in deep shade. Put the camera on a tripod in manual mode, and with each frame make the shutter 2 stops longer and take 2 stops of light away, so the brightness stays the same while only the time changes:

1. 1/60 s, f/4, ISO 1600
2. 1/15 s, f/4, ISO 400
3. 1/4 s, f/4, ISO 100
4. 1 s, f/8, ISO 100
5. 4 s, f/16, ISO 100

If your meter does not read correctly at the first setting, shift all five by the same number of stops. It takes about 10 minutes. Judge the result by laying the five frames side by side. The histograms should look almost the same; if one is brighter, a setting slipped. Then look only at the water and decide where it changes from drops to streaks, and from streaks to silk, and which one you prefer. The rocks should be equally sharp in all five. If they are not, the tripod moved. The exposure triangle explains why these five settings give the same brightness. If you have time left, repeat the idea on clouds from a high window, or after dark on passing cars, and see how much longer each needs than the water did.

Questions about long exposure photography

What shutter speed counts as a long exposure?

There is no official cut-off. In practice it means a speed chosen so that motion records as blur, usually from about 1/4 second upward, on a tripod. For fast water that can be half a second; for clouds it is minutes.

Can I do long exposure without an ND filter?

Yes, whenever the light is low: at dusk, at night, in deep shade or on a dark overcast day. In bright sun the slowest speed at ISO 100 and f/16 is about 1/100 second, so a filter is the only way to go longer.

Why do people disappear in long exposures?

Each spot in the photo records the average of what was in front of it during the whole exposure. A walker covers any one spot for a fraction of a second, too small a share of a minute to show. People who stand still for a good part of the exposure leave a ghost.

Does a long exposure on a digital camera need extra time, like film?

No. Film loses sensitivity in long exposures and needs extra time, which is called reciprocity failure. Digital sensors respond in proportion to time, so the calculated exposure is the right one; the cost is more noise and hot pixels, not darker frames.

Why does my long exposure have colored specks?

Those are hot pixels, caused by a small electrical leak in the sensor that grows with exposure time and with temperature. Long exposure noise reduction removes most of them at the cost of doubling the time, and noise reduction in editing deals with the rest.

How do I focus with a dark ND filter on?

Focus before the filter goes on. Compose and focus without it, switch the lens or camera to manual focus, then fit the filter without touching the focus ring. A strong ND makes the viewfinder too dark for autofocus or your eye to work through.

Want to check what you know about long exposures, star trails and light trails? Try the long exposure and night photography quiz.