Long exposure photography is a technique that can help capture the movement of subject matter, allow more light onto a sensor to brighten an image, or even get creative and artistic with your camera. Understanding what long exposure photographs are and how they work can be confusing at first, but with a little practice and some background information, you'll be on your way to taking more creative photos. Keep in mind, this is an introductory article aimed at explaining basic concepts of a camera's functionality, and how to utilize the functions in their appropriate situations.
Let's start with a quick definition for the word "exposure". In digital photography, this refers to the amount of time that light is permitted to reach the camera's sensor. Each digital camera has an internal sensor that records information about the light passing through the camera's lens. This information then gets translated into a digital language that can be read by a computer and pieced together to create an image of what was visible through the camera's lens. Exposures are taken using a measured unit of time, also referred to as "shutter speed", ranging from a fraction of a second to several minutes or even hours, and are recorded as one single image.
Now let's look at our first example. If you want to freeze the motion of a subject, such as a skier slashing through powder, you would want to use a short exposure time. A shorter amount of time exposing a sensor to light means less movement of the skier during the length of the exposure, therefore reducing image blur and avoiding the use of too much light (also known as "over-exposing"). In this case, the shorter the exposure time, the sharper the image of the skier.
Vail, Colorado // Skier: Ryan Downing // Photographer: Jason Wilson // Canon 5D Mark III + Canon 24-105mm f/4L // ISO 100, f/4, 1/640"
The above photo was taken using a short exposure time of only 1/640th of a second, which eliminated most of the movement of the skier. This effectively "freezes" him in time, despite the fact he was moving faster than 20mph. This short exposure time is easier to achieve during the daytime, as there is an abundance of natural light provided by the sun to properly expose the image. But what if you want to expose a photo at night when there is very little ambient light around?
This is where we introduce Long Exposures.
While there is no official length of time that separates short exposures from long, the message is clear: long exposures simply refer to the process of allowing light to reach the camera's sensor over a longer amount of time. This process comes in handy frequently when taking landscape photographs at night, as there is generally very little light to work with. When the camera's sensor receives very little light, it can allow that light to be recorded over a longer period of time in order to "brighten" the image. The amount of time required for each properly exposed composition varies and can be manipulated in a variety of ways, but the basic concept remains: the longer a camera's sensor is exposed to light, the brighter the resulting image will be.
Emerald Bay, California // Photographer: Jason Wilson // Canon 5D Mark III + Rokinon 24mm f/1.4 // ISO 400, f/1.4, 25"
The above photo was captured over a duration of 25 seconds, utilizing a landscape-friendly low-light lens*. As the camera's sensor was exposed to light for 25 seconds, we would consider this a long exposure. Emerald Bay is located on the southwest shoreline of Lake Tahoe, an area with very few structures or lights. This allows us to expose the entire scene evenly, unlike the light-polluted shore on the opposite side of the lake. The photo was captured around 9:00pm and was complemented by a full moon that brightened up the landscape significantly. Though the photo took 25 seconds to expose properly, it was a short enough exposure to record a landscape image with very little movement of the night sky.
So what if you want to introduce movement into your landscape photos at night?
Pismo Beach, California // Photographer: Jason Wilson // Canon 5D MK III + Canon 35mm f/1.4L II // ISO 100, f/2.8, 602"
There are certain occasions where exposing a camera's sensor to light for a long time can produce beautiful, dramatic effects. The above photo of Pismo Beach, California showcases the movement of both the stars and the waves over a duration of 10 minutes, producing a star-trail effect in the sky and silky-smooth water along the coast. The longer you expose a photo, the more movement you can capture.
Most DSLR cameras have a manual ("M") mode that will allow you to adjust all of the settings individually. When placing your camera in the "M" mode, you can adjust your camera's exposure times variably between roughly 1/8000 of a second and 30 seconds. If you wish to expose an image for any duration longer than 30 seconds, a shutter release remote is needed. After attaching the shutter release cable to your camera, switch the mode to "Bulb" ("B") and your sensor will record as long as the shutter release button is held down**. Keep in mind, a tripod is recommended for all long-exposure photographs.
Let's have a quick recap, then we can get creative:
- Digital cameras have built-in sensors that record information about the light that passes through the camera's lens
- The amount of time that a sensor is permitted to record this light is called an "exposure" or "shutter speed"
- A shorter exposure, such as 1/640th of a second, will "freeze" the motion of your subject matter
- A longer exposure, such as 10 minutes, will record movement over the duration of the exposure and convert it into one single image
California Coast // Photographer: Michelle Tomaszkowicz // Canon 5D Mark III + Canon 24-70mm f/2.8L II // ISO 1000, f/5.6, 30"
Now that we understand how the exposure works when taking photographs, let's throw a new element into the mix: human interaction.
In January of 2017, a fellow photographer and I caught a sunset in Southern California. She brought along some steel wool and wanted to get creative with it. Setting the camera's shutter speed to 30 seconds, I stepped in front of the lens and lit the steel wool, spinning it above my head. Since the camera is simply recording light that comes through the lens, you can introduce any light source you desire and quite literally paint with light.
If you'd like to learn how to create long exposure photographs under bright lighting conditions, check out my explanation of neutral density filters here.
*Detailed information about lenses, including apertures, focal lengths and their potential uses will be described in a future post.
**Purchasing a shutter release remote with a locking mechanism will allow you to move freely for the duration of the exposure without having to physically hold the button down.