How to do Long Exposure Photography and get Awesome Photos!
I live in rural Alabama currently. There isn’t that many great landscape opportunities to be had here. When I come across one, I try to take full advantage of it. I learned about an actual waterfall near my house the other day. Its about 15 feet high and crescent shaped as the land contours out of town. The Alabama red clay has been eroded to the bedrock and the falls formed as the water cut through the soft clay. Its actually a pretty nice little fall, albeit seasonal and based on the rainfall. The water tumbles in a moderate flow over the bedrock into a small sandy pool before bubbling through some large pocked boulders on its continuing journey down the creek.
Its a short trek off the road, so it was a perfect opportunity to get out in nature on short notice and play with some long exposures. I am a sucker for the averaged dynamics of milky, smoky, flowing water and mirrored pools in a long exposure shot. Unfortunately to get a truly milky look, it takes a really long exposure. I am talking about minutes, even in mid-day sun.
How do you accomplish this without blowing out your image or burning out your sensor as it sits exposed to the light for minutes at a time? Through the use of Neutral density filters, more specifically nine or ten stop ND filters. These filters can urn day into night, and will take some awesome pictures as long as you follow a few simple rules and techniques.
First and foremost, you must use a tripod, preferably something really sturdy. I myself use an Vanguard Abeo Pro 283CGH Carbon Fiber tripod with a great pistol grip ball and panning head. I also have a great little meFoto Roadtrip, but I would not use it on this kind of shot because the extra weight of a large tripod, and carbon fiber, work to help dampen any environmental movement which is really important over such long periods of time. In this case, I had to put the tripod in the water flow to get the angle I wanted, so I needed to make sure the tripod wouldn’t shift.
That’s point two. Put the tripod in a sturdy place where it can’t slip and ruin your shot. I figured out the angle and location of the camera, bending over the water precariously till I had a good pre-visualization of the image. I then moved the center of the tripod over the area, and extended the legs till I had secure footings.
The next thing you will want to do is get the camera in position, aim, focus, and shoot off a couple of test shots. Make sure you are using a small f-stop such as f/16 but not one so small it causes diffraction. Know your lenses and their limitations. Set you ISO as low as it will go, ISO 50 -100 preferred. This will reduce the noise as much as possible in the shot. This is really important, as I’ll discuss below. Lastly place the camera on manual, as you don’t want the focus to shift after you place your ten-stop ND, fire your test shots and make sure you have a good, balanced exposure before continuing. Use of a light meter is recommended for the sake of convenience as leaning over a camera perched in the water is asking for trouble. Even an iPhone/Android Light meter, like Pocket Light Meter, will work for this since you are getting an overall light reading and incidence readings will work fine. Mathematics is coming.
Now that you have prepped your shot, you’ll want to carefully put your ten stop ND on and watch your Live view screen or viewfinder go black. You can’t see anything anymore! Gasp! Don’t worry, all that prep work means things are just fine with your focus and composition. All you need to do now is some math to figure out what your new shutter time is.
There are several apps available for this on both Android and iOS. On iOS, I use ND Timer as it not only does the math for me, but includes the timer. On Android I use a combination of a Timer and Light Meter Tools to accomplish this. Say your exposure before the ND was 1/30 @ f/16. You just reduced the shutter by ten stops to 34 seconds for the same exposure. The exposures are on a logarithmic curve so the time gets exponentially longer based on what your initial shutter speed was and the time can add up quick.
Now you have your image, composition, focus, and timing done. Put the camera into bulb mode and use a remote shutter release to trip your shutter. Also use the mirror up mode and give yourself a second or two before the second shutter trip so the camera can settle from the mirror slap. You want things as steady as humanly possible. Once the shutter is tripped, wait for the timer to expire, close the shutter and revel in your wonderfully awesome long exposure photograph!
Why a long exposure?
There are several reasons to do a long exposure. First of all are the cool dynamics of motion blur. Motions blur starts to appear at shutter speeds of 1/30 and below generally. The slower the shutter the more blur. You want to show some movement in a waterfall or sports scene, you can use any number of ND filters to slow your shutter down just enough to catch some motion blur for effect. I’ll often use a simple 3 stop ND, or Circular Polarizer, to drop the shutter just enough for a hint of movement in the scene. The slower the shutter the more the blur. Drop a ten stop onto your camera and waves level out into a foggy or mirror like appearance. Falls become soft, milky flows.
You can remove things completely with long exposures. Most of you are familiar with blurring cars in low light to get those cool tail light streaks in your shots. Well if you continue to slow the shutter down long enough, those lights won’t remain in the frame long enough to leave an imprint on the sensor and then your traffic, or people, will completely disappear. It can turn a metropolis into an eerie ghost town in the middle of the day!
Lastly, the longer the sensor is exposed to the light the better the colors become. Your blacks will be blacker, your colors more saturated, and your tonal values more balanced. Edges will look sharper without increasing the contrast, and images will generally be softer toned and contrasted. In the image above, you can see how the left side is harsher without all the intricate details and deep blacks of the long exposure on the right. The colors are better as well on the right. That’s not to say the image on the left is necessarily bad, it may be the perfect thing you were going for.
As with any slow shutter techniques, unintended blur is the most common complication. Hopefully the use of a strong, sturdy tripod in a good location as well as the use of a remote will minimize that.
Another complication is light leak. You are leaving the sensor open for an extended period of time. Any light leaks, especially from the viewfinder, will be visible in your image. They will show up as purple blurs, light streaks, etc and will ruin the image you just spent thirty minutes setting up and taking. I always cover my viewfinder with a black cloth, the viewfinder cover, or some other device. Some bodies some with automatic viewfinder shutters, check your manual.
Lastly is noise. Noise will take a perfectly awesome long exposure and ruin it. Most of this is taken care of by using low ISOs, however, when you leave the sensor open for extended periods the sensor will develop “hot spots” which will show up as strong color noise (red/blue spots) in your blacks. These are almost impossible to remove in post-processing and most techniques require some kind of blurring to fix. So, before you click that shutter, go into your menu and turn on “Long Exposure Noise Reduction” in your settings. This will take a second image immediately after your first with the shutter closed. The camera will then take this image map al the hot spots in-camera, and then remove them from your long exposure leaving a beautiful, clean image behind. The downside to this is that it doubles the length of your exposure since its taking a second shot of the same length to do the mapping. Your 8 minute exposure just turned into a 16 minute one. On my Nikon D600, this time shows up as a blinking “Job NR” in the top LCD which seems to take forever. 16 minutes can be a long time during the golden hour, just to see if your image worked. If it didn’t you are now fighting the light to get another shot. However, not doing this step could potentially leave you with an ugly mess in post (see image), so plan accordingly and use Long exposure NR!
I hope you found this quick tutorial on long exposures helpful. I wrote it up based on my own lessons learned with such things as light leaks and noise reduction. I love it when I see the image on my camera and its exactly what I pictured after waiting patiently for time to pass. Sometimes, the wait can seem to take forever, but if you set everything up right, the wait will be worth it! So go out, experiment, and take some long exposures. Share with us what great things you were able to visualize and capture in the comments. I look forward to seeing them.