All photography, at its most basic, is the way in which light exposes itself to a recording medium (plate, film or sensor). Three metrics govern this- the size of the hole the light passes through (aperture), the amount of time the medium is exposed to the light (shutter speed), and the sensitivity of the medium to recording light (ISO). A ‘well exposed’ image balances the three metrics to produce an image that reflects the artistic vision of the photographer. Typically, this is an image wherein the darks are not lost to textureless shadow, the whites are not blown out, the colours are representative of the scene the photographer viewed, and the main subject of the image is well represented in form and emphasis.
Of course, changes to each of these metrics affects how the photo turns out, even if the overall exposure of the medium to light remains the same. Changing aperture affects the amount of the image, front-to-back, that is in focus. Changing ISO affects the grain, or texture of the image. And changes in shutter speed sharpen or blur moving objects.
Generally, blur in a photo is unappealing. However it can be used to artistic effect. One form of this is to give the sense of motion. Panning on a slow shutter speed with a moving runner, bird or vehicle can, done well, freeze the subject in sharp detail but blur the background, giving a sense of speed and movement.
When part of the image is stationary and another part moving, the effect can also be pleasing. In the above image, the beach and rocks are stationary, while the sea and clouds are moving. Typically, waves move slowly enough that a moderately fast shutter-speed (say, 1/50th of a second) will freeze them quite nicely and eliminate any blue. As you lengthen the amount of time the sensor is capturing light (generally longer than 1/10th of a second), waves start to blur a little. The longer the shutter is open, the more the waves begin to disappear, the surface of the water becomes smooth, and areas of turbulence appear to mist over.
The above photograph was shot over 60 seconds- a full minute in broad daylight. Typically, leaving the shutter open so long at any aperture will cause so much light to hit the sensor that the image will simply wash out- all you will see is an empty white frame. To overcome this, I use a Neutral Density (ND) 400 filter- a colourless dark glass that goes over the front of the lens which does not change the colour of the light, but reduces it 400 times- allowing you to open the shutter 400 times longer than you would under other circumstances. I stack this with a polarizer- because in bright daylight even the ND400 can become overwhelmed- and this allows me to keep the shutter open for up to around two minutes in full sun.
I enjoy taking shots like this, as they paint reality from a different perspective. Time folds in on itself, and you get to see the world in a way it doesn’t usually appear. However they take time to set up. You need to frame the image on the tripod and adjust the polarizer first. Once you have the right composition and have pre-focused the image, you need to switch to manual focus, and then you can then screw on the ND400. You need to do this without rotating the polarizer, or you will shift the tones and contrast in the image. You also mustn’t twist the lens or you’ll throw the image out of focus. You also need to turn Image Stabilization off (if you have an IS lens), as on long exposure, the IS motor can create a feedback loop that actually causes the lens to vibrate. Then you use your remote trigger to take the photo for the desired length of time. Even this can be a bit fiddly, as the camera is giving you no real feedback as to how long to expose the image for (it goes beyond its metering parameters), so you often need to bracket several long-exposure frames before getting it quite right. Each frame might take anywhere from 30-120 seconds to take (in broad daylight), so getting just one shot can take you ten minutes of fiddling. Do five or six, and you’ve used up your allotted photographing time for the day!
To see the image in more detail, click to view the larger size. If you zoom in on the rocks you’ll see the misting effect of the breaking waves. See if you can spot the moving ships. And please forgive the lens spots…
This isn’t a particularly exciting variety of long exposure daylight photography- it’s just the only one I’ve taken in a while. I do enjoy it though- for both the challenge and the output. Now that I’ve rediscovered my ND400, I hope to have a few more of these pop up from time to time.
Above: Trentham Falls, outside Daylesford, Victoria, Australia, as viewed from behind the falls themselves. Hand-held at slightly long exposure has given the falling water a slightly silky texture. Among the challenges of taking this image were the issue of shooting from a darkened vantage against a lighter sky and trying not to allow much of the image to burn out. Additionally, several plebs managed to find themselves in the frame, so I removed their pesky presence in post-processing to give the image a more serene look. I actually had to wait up here for a good six or seven minutes for a couple of kids to step out of the frame at bottom, where they had been chucking big rocks into the water. Overall I like the quiet scene and the relatively soft palette of greens and earthy tones.
Above: Highway bridge, Savannah, GA. You don’t generally get many good shots through a car windshield, but this spur-of-the-moment snap-shot (I use the term to refer to how quickly it had to be lined up and taken, not the camera it was taken on) works for me. Again the lines of the bridge struts give a great sense of motion, leading the eye into a contrasty late-afternoon sky, and a broad horizon giving the feeling of wide open spaces. It’s a shot that captures movement and an enjoyable juxtaposition of dramatic engineering and natural beauty.
