When and How to use Long Exposure Photography
One of the biggest challenges we face as nature photographers is how to tell the story of a particular location. We work to create an image that will let our audience know what it felt like to stand before the scene and take it all in. We see the motion of the water and smell the damp earth and hear the leaves rustle in the breeze. Wouldn’t it be lovely if our nature photography could communicate at least some of what we experienced? While I haven’t figured out “smell-o-photo” just yet, I have enjoyed using long exposure photography to tell the story of motion in my images. And I am always looking for ways to use slower shutter speeds to help the viewer feel like they are there.
What is Long Exposure Photography?
One of the three components of the exposure triangle is shutter speed, which is essentially a measure of time. It’s the time the shutter is open and light is striking the sensor. Using a longer than normal shutter speed to blur the moving parts of a scene is referred to as long exposure photography. It is a highly-effective creative tool when we want to imply motion in an image, particularly when the image also contains static elements. I use this technique often because one of my favorite things to photograph is moving water.
When to Use Long Exposure Photography?
When does long exposure photography come to mind when I’m out in the field? Anytime I’m photographing something that is moving, I make a critical decision on what shutter speed will best tell that story. If I want to freeze the motion of a dog catching a frisbee, for example, I choose a really fast speed. I hope to stop the action at its peak and have everything in the frame as sharp as possible. But when I’m photographing something that is moving and I want to show that motion instead of freezing it, I turn to a much slower shutter speed.
By allowing the shutter to remain open for a longer period of time, I allow the parts of the scene that are moving to blur slightly (or a lot!) and thereby convey a feeling of motion. So at its core, long exposure photography is simply the choice of a slow shutter speed used creatively to create a feeling of movement.
You can use long exposures to tell your story – whenever you have something moving and something completely still in a scene.
In the image below, these pylons are not photogenic in the least. They are behind some shops in the middle of town in Bandon, Oregon. You’d never give them a second look. At high tide, when water levels are covering part of the pylons, you get this shot with an “ordinary” shutter speed. This is a throwaway shot, certainly not “wall-worthy.”
But when I have a scene that features strong structural elements (the pylons) next to something that is moving (the water in the breeze), I immediately think of a long exposure technique. The second image is the exact same scene, but this time I’ve used a much longer shutter speed. What a difference, and all I did was use a longer shutter speed. The water is smoothed out and has a warmer color which gives the image an entirely different mood. While this certainly wasn’t my favorite shot from my week in Oregon, it was a fun opportunity to practice my long exposure technique.
Another time to use long exposure in your work is when you want to show the motion of water over rocks. I photographed this amazing scene in the Smoky Mountains a few years back, and had perfect conditions to do a long exposure. It was overcast so I knew my exposure would allow a longer shutter speed. There was absolutely no wind that day, which is essential for the still component of the shot. If the trees had been moving (even just a tiny bit) and I had kept my shutter open long enough to blur the water, the trees would have been blurry and the image would have been ruined. So when you are thinking about using long exposures, be sure to check the “still component” of the shot and make sure it is indeed still.
I photographed this scene with at least six different shutter speeds (with equivalent exposures) so that I could choose my favorite water when I got home to the computer. This is good field practice, because you have fewer regrets later!
You can also use long exposure photography to capture the reflected light on water, star trails, use it to capture creative images with in-camera motion and more. Here are some photos on Visual Wilderness created with slow shutter speed.
How to use Slow Shutter Speed
Remember, the exposure triangle works in a reciprocal fashion. If you lengthen one leg, you must shorten the other leg or legs to compensate for an equivalent exposure. The goal with long exposure photography is to keep the shutter open for a much longer period of time than what you would normally expect. Therefore, I set the ISO and aperture to the smallest values to try to force my shutter speed to the longest interval.
My technique for achieving this desired long shutter speed is to begin with a proper exposure, one which balances the histogram to avoid blown highlights but shows good dynamic range. I make sure I have my ISO on the lowest setting and my aperture on the smallest opening (that avoids diffraction) so that my shutter speed is the longest possible. Next, I take a shot to see the effect of that shutter speed. I often take multiple shots at different shutter speeds so that the blur effect is altered in each shot. I choose my favorite in post production. This is easily done by using auto ISO in manual. You start with ISO 100 and a balanced exposure, and then switch to auto ISO. On subsequent shots, just shorten the shutter speed for each exposure and allow the camera to adjust the ISO. This will result in images that have various amounts of blur, then you can choose your favorite later on the computer.
For the shot of the pylons, even by reducing my ISO to 100 and stopping down my aperture to f16, I still only had a shutter speed of 1/25 second. That was definitely not long enough to smooth out the water. So when I’ve done everything I can to get a longer shutter speed, but still need more time for the shutter to remain open, I must turn to a filter that reduces the amount of light that enters the camera. I almost always use a polarizing filter when shooting landscapes. It helps a bit because it reduces light entering the camera by about one stop.
But in this pylon example, the polarizer was already in place and the shutter speed was still too short. So I turned to a neutral density (ND) filter to reduce the amount of light getting to the sensor. ND filters are an essential piece of your kit for long exposure photography. In the above example, I used a “10-stop” ND filter and that gave me the 36-second shutter speed that smoothed out the water and turned a very ho-hum location into a fun shot.
Of course, an ND filter may not be needed if you are using long exposure photography at night or in a very low light conditions. I was in Bandon, Oregon and the light was too dim for any more shots of the beach. But as I went up the hill and back to the car, I took one last look at Face Rock. It was so dark that I could barely make out the shape of rocks and there was almost no discernible color in the sky. The sea was moderately rough and of course Face Rock was still. Hmm, something moving and something still. Could I just do a really long shutter speed and see what I get? Sure!! So this is the end result of a wild “shot in the dark” and turned out to be one of my favorite images of the trip.
I hope you will give long exposure photography a try! Because I am so fond of the technique, I always look for ways to use long shutter speeds to my advantage.