Long Exposure Photography: The Basics
Long exposure photography is a great way to create visually stunning images that can almost transcend reality. Learn how to do it with Square Pixel Photography.
What Is Long Exposure Photography?
What’s in a name? In this case… the answer to the above question 🙂
When taking a photo the shutter speed is ‘normally’ measured in fractions of a second. In dim light with a relatively still subject, or when using a flash, the shutter speed might be as slow as 1/30 of a second. In a strongly lit scene or when shooting action your shutter might be set to 1/4000 of a second.
Long exposure photography slows things right down.
There is no formal definition of what shutter speed constitutes a long exposure, but I generally think of it as anything that allows a photo to show the passing of time by showing movement in the scene.
It is possible to get a long exposure shot of fast flowing water in a little as one second. At the extreme end, long exposure photography can have shutter speeds measured in hours.
If you need a refresher on what Shutter Speed is, you can read our Shutter Speed In Photography article.
Long Exposure Photography Examples
In ‘normal’ photography, the aim is usually to freeze all motion. This gives a sense of capturing a single moment in time. A long exposure photo usually aims to show some movement that portrays the passing of time.
A common subject for showcasing movement is a waterfall or a fast flowing stream.
Below, the first photo was taken with a relatively fast shutter speed designed to stop the motion of the water flowing over the waterfall. The second photo shows the long exposure version.
Waves are another great subject for long shutter speeds. You can see below that slowing down the exposure smooths out ripples in the water to show a glass-smooth surface.
Another common example of long exposure photography is to show clouds moving across the sky. You can see the difference between the ‘normal’ and ‘long’ versions of a scene with clouds below. You can also check out the water and Ferris wheel:
Equipment For Long Exposure Photography
There are a few items that will help immensely with taking a long exposure photo.
In order to keep the still bits in your photo sharp you will need something to keep your camera still during the exposure. Small vibrations or other movement while the shutter is open over a long period of time will turn your long exposure into a blurry mess.
The longer your shutter speed, the more sturdy your tripod will need to be.
Also, longer focal lengths will also need more care, as not only are they more sensitive to vibration due to the focal length, but the equipment is generally more affected by wind and other sources of vibration.
Neutral Density Filters
Putting a neutral density filter (or ND filter as they are often called) in front of your lens will cut down the amount of light entering the camera. This is what allows for slow shutter speeds during daylight hours.
ND Filters come in different strengths and range from 3 stops, up to 20 stops. A three stop filter will change a shutter speed of 1/30 of a second to 1/4 of a second. A 15 stop filter will slow that down to 16 minutes.
Each stop will halve the amount of light coming into the camera and thus double the shutter speed time.
There are also two different types of filters you can buy. Round screw-in types that fit directly onto the front of your lens, or square filters that fit into a special holder that attaches to your lens. I highly recommend square filters as they (at the very least) are much quicker and easier to use. Trust me, you’ll REALLY appreciate the ability to easily remove a filter if you start doing longer exposures where you can’t see through the viewfinder.
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Square Filter Examples:
Round Filter Examples:
Most cameras only allow for shutter speed settings of less than around 30 seconds or so. Anything more than that requires the camera to be set to ‘bulb’ mode and a remote control to hold open the shutter for the required time.
Remotes can come in wired versions that plug directly into the camera, or as a dongle that can then be remotely controlled by an app on a phone.
Camera Remote Controls:
A few recent camera models will allow for much longer speeds to be set on the camera, but I would still strongly suggest using a remote of some sort to ensure you don’t move the camera (even slightly) by pressing the shutter button.
A Basic How-To
Below is a very basic set of steps you can follow when taking a long exposure photo. Obviously every scene is different, but this is a rough guide to get you started:
- Find a scene with both still and moving elements
- Set up your camera on a tripod and compose the scene. Don’t add any ND filters. Lock down the tripod when you’re done.
- Set your camera to ISO 100 in Aperture Priority mode. Select an appropriate aperture and take a test photo
- Review the test photo to make sure it is correctly exposed and you’re happy with how it looks. Take note of the shutter speed
- Add an ND filter to your lens. Stronger ND filters will give you longer shutter speeds. Use an app on your phone to calculate the new shutter speed, using your test photo as the base speed.
- Change your camera to bulb mode, leaving the ISO and aperture the same as your test photo.
- Attach the remote control and take the photo with the long shutter speed. Use your camera as a timer to know when to stop the exposure.
It sounds like a lot of steps, but once you do it a few times you will get quite quick at being able to set things up. The longest part is waiting for the timer to count down while you take the photo.
Choosing A Shutter Speed
When starting out with long exposure photography it is tempting to choose the strongest ND filter you have and set the exposure to as long as possible.
Longer isn’t necessarily better though.
You need to think about how much movement you want to capture and choose a shutter speed that will give you the look you’re after.
A waterfall or fast moving stream will show a great amount of movement in a couple of seconds, anything more might start to obliterate too many details. Slow moving clouds might need a couple of minutes to get the effect you’re after, but too long and you will end up with a perfectly flat and uninspiring sky. At the extreme end, a star trail might need several hours to create the look you’re after.
The best thing to do when you start is to experiment with different speeds and scenes to see what works and what doesn’t.
There are no hard and fast rules when it comes to the ‘correct’ shutter speed to choose. Much of it will come down to your artistic desire and the ‘look’ you are trying to create.
Turn off any optical stabilisation that your lens or camera may have. During a long exposure the elements involved in stabilising your lens may ‘drift’ and will cause blurry photos no matter how solid your tripod is.
If you add a strong ND filter to your lens you probably won’t be able to see much through the viewfinder or LCD screen. Compose your shot with the filter removed and add it just before you take the shot. A square filter system makes this much easier as the entire system will just pop off the front of your lens, rather than having to unscrew a filter.
As exposure times get longer, your camera will probably struggle to work out a correct exposure time with it’s built in meter. If you are using ND filters you can take an exposure reading with the filter removed and then use an app (or your brain if you’re good at maths) to calculate the new exposure including the filter.
Be aware that ANY movement in the frame will show as blurry when shutter speed gets longer. In the image below I hardly noticed the boats moving on the lake – but 30 seconds is a long time for things to move around:
If you don’t have a remote and your shutter speed is below your cameras 30 second limit you can also just use the ‘self timer’ function to delay the photo a couple of seconds after pressing the shutter button. This will help reduce any movement caused by you pressing the button.
Subject Ideas For Long Exposure Photography
- Star Trails
- Light Painting
- Moving Water
- People Walking
You can also use a long exposure to reduce the prominence of moving people in your shot. You need to be careful that a person doesn’t stop for a relatively long time in the same spot though, as they won’t be blurry enough to disappear.
More Long Exposure Examples
Below you can see a few more examples of long exposure photography. I have only just started exploring this genre of photography and already I’m hooked.