|Manipulating the texture in a photograph by changing shutter speed has been around as long as photography itself. The effect is most commonly employed in scenes with water, but it can come into play in other situations, as well.|
From smooth and serene to rough and woolly, texture in a photograph can convey feeling and emotion that reflect the photographer's response to the subject and surroundings. Using filters is the key to creating texture in landscape photography. It's more than simply screwing a filter in front of your lens; it's understanding the relationship between exposure time and subject movement. This means knowing which filter to use and how to control the exposure time through ISO and aperture; it also means knowing how long is too long and how short is too short.
Let's start with what filters to use. There are two varieties of filters photographers can use:
Thread-on filters: round filters that thread onto the front of the lens, or;
Frame filters: square or rectangular filters that fit into a special filter frame, which is attached to the front of the lens.
I use the frame filter variety. Working with filters is typically done under light conditions that are rapidly changing—seconds can make the difference between getting the image and missing the prime light. Frame filters allow me to make rapid changes; I don't have to thread and unthread the filter to the front of the lens, which may disrupt my focus or move my composition. Instead, I can simply slip the filter on or off with one quick movement.
In addition, the graduated neutral-density filters of the thread-on variety fix the horizon position in the dead-center of the composition, which is the least desirable placement, whereas the frame filters allow the photographer to position the horizon anywhere in the composition. It's this creative control and rapid-change feature that make working with frame filters a joy and, if properly used, can extend your vision to new dimensions.
How Much Density Do You Need In A Neutral-Density Filter?
Neutral-density filters come in a wide array of densities. Some filter manufacturers refer to ƒ-stops to indicate the density of a filter, such as a "3-stop ND filter," which means it filters out 3 stops worth of light. Other manufacturers use an ND number system, so a 3-stop ND filter would be referred to as an "ND 0.9 filter," or a 6-stop ND filter would be referred to as an "ND 1.8 filter." Under the ND number system of nomenclature, the ƒ-stop is divisible by 0.3. This can cause some confusion; however, you should just note that if there's a 0 in front of or a decimal point in the ND number, the manufacturer is using the ND number system, not the total number of ƒ-stops the filter blocks. My favorite ND filters are the 3-stop (ND 0.9), 6-stop (ND 1.8) and 10-stop (ND 3.0) varieties.
Graduated neutral-density filters are applied in situations where the sky is much brighter than the foreground. In landscape photography, this can happen much of the time, particularly during sunrise or sunset when the light is most desirable. The filters are clear on one end and transition to neutral density on the other. There are three varieties of transition: hard, soft and attenuator. The hard graduated neutral-density filter has a hard edge, where the transition from clear to dense is very abrupt. The soft graduated neutral-density filter has a smooth transition from clear to dense; this is the variety that's most often used for landscape photography and is my personal choice. The attenuator graduated neutral-density filter is a gradual transition over the entire filter. Just like neutral-density filters, graduated neutral-density filters come in different densities. They use the same numbering system based on 0.3 per ƒ-stop. The graduated ND filters I use the most are soft grads of the 2-stop (ND 0.6) and 3-stop (ND 0.9) varieties.
Long Or Really Long Shutter Speeds?
Texture in a landscape image can be the result of many factors: subject surface, lighting or composition. It can also be the result of movement recorded with either a fast or slow shutter speed. Texture created by the movement of the subject can be manipulated to create different desired results of either smooth or rough, or something in between. Rivers, streams, waterfalls, waves, grasses, flowers or leaves blowing in the wind are all great subject matter that can provide for the manipulation of texture.
Long shutter speeds—1 second or longer—can create spectacular effects. The question is, how long? Longer isn't always better. It will depend, in part, on how much texture—or lack of texture—you want. In many cases, waves on the ocean or a large lake can be made to appear mirror-smooth with a 30-second exposure, yet waves washing over rocks can, in some instances, all but disappear with a 30-second exposure. In this case, the waves washing over a rock may better appear as a smooth white and well-defined water flow, which would occur at 1 second or 2 seconds of exposure.
Using and applying neutral-density and graduated neutral-density filters to a scene requires a slightly different approach than what many photographers are used to. Careful selection of vantage point, lens, composition, depth of field and point of focus and a predetermined vision of the final image are the hallmarks of a seasoned landscape photographer. Adding a timed exposure of 10, 20, 30 seconds or more into the mix, during which the subject changes and moves, adds an entirely new dimension to the image-making process. It requires you to carefully control all aspects of the image-making process up to the point of opening the shutter—then you must let go of the process and trust to providence that the forces in front of your lens will grace you with a beautiful image.
Manipulating texture in an image requires the use and alteration of four factors: filter density, camera ISO setting, aperture and shutter speed. Let's say you want to achieve a shutter speed of 30 seconds to smooth the waves on a lake and give the lake's surface a mirrorlike look. You might start by setting your ISO to 100 (or lower, if possible), then stop down your aperture to ƒ/22, and the resulting exposure might be only 1⁄2 sec.
At the edges of the day, long exposures can create an especially ethereal look in a scene like this one.
If you place a 6-stop ND filter in front of the lens, you can reduce the exposure to 30 seconds. Using the 6-stop ND filter, you now compose an image of waves washing over a rock in the foreground. A 30-second exposure results in an image of the rock with some wispy white fog over the rock, but not the feeling of movement you anticipated. By changing your ƒ-stop to ƒ/11 and altering the camera ISO to 400, you have a shutter speed of 2 seconds, and the resulting image shows a nice, smooth texture of water flowing over the rock.
It's this matrix of creative control that really gets my adrenaline pumping when I'm working in the field and looking for creative compositions and subjects.
To see more of John Gregor's work and sign up for his workshops, go to coldsnap.com.
|Gear Up For Effects | By The EditorsWater is the most common subject for using slow shutter speeds to manipulate the texture in a scene, but it's not the only subject where you can employ the effect. In the example above, you can see the possibilities of a traditional landscape image on a breezy day. A scene like this one is particularly interesting because it has an element of unpredictability. Everything depends on the little gusts of wind. Besides ND and split ND filters, there's some essential gear for creating images like this.
Sturdy Tripod: You need to be able to anchor your camera very well, especially if there's any wind. Whether you use aluminum, wood or carbon fiber, the tripod should have ample capacity for the weight of your camera and lens.
Large Ballhead: In a lot of situations, you can get away with an undersized head for your rig, but not when you're playing with shutter speeds of 10, 20 or 30 seconds. If you can't fully lock down your rig, you run the risk of slippage, which will ruin the photo.
Remote Shutter Release: For the very best results, employ mirror lockup in your DSLR, and trigger the shutter with a remote release to avoid any shaking as you depress the shutter button.
If you don't have a remote, try using the camera's built-in self-timer. If you're shooting with a mirrorless camera, obviously, the moving mirror isn't a factor, but a remote or the self-timer is still important.