Neutral Density Filters
If you're starting to use your camera in more creative ways, you will likely start to notice some of the restrictions that come when shooting certain subjects. Ever wanted to capture a beautiful portrait of someone in broad daylight using a shallow depth of field? You'll eventually come to find that you are restricted to no wider of an aperture than roughly f/2.8 before your images start blowing out the highlights. That will virtually eliminate the appealing bokeh that comes when using prime lenses at wide apertures like f/1.4. How about trying to capture the movement of water or clouds during broad daylight? You will begin to notice that anything slower than 1/100" starts to do the exact same thing. What's happening here? In basic terms, there is too much light hitting the sensor causing overexposure. Check out this write-up about the introduction of the neutral density filter and where it can be utilized to capture a beautifully unique photo in harsh lighting conditions. Keep in mind- this is not an introductory tutorial on how the camera works, so having a basic understanding of photography is necessary to fully comprehend this process. Check out my introduction to long exposures for more basic information on camera functionality here.
Once you find a landscape lens that you like (generally with a wider angle to capture more of your surroundings) or a portrait lens with apertures of f/2.8 and wider, you're ready to play with light in more creative ways. Most cameras can stop down the light to generally 1/8000 of a second, but that eliminates all motion blur (aka movement) in an image by "freezing" the frame. To allow movement, you need a long exposure to allow everything in the frame to move fluidly over the duration that the shutter is open. To have a long exposure without letting too much light to hit the sensor, you have to compensate by stopping down the aperture to f/22, which restricts much more light but also widens your depth of field (generally a good thing in landscape photography). One thing you'll notice, however, is even at f/22, you can only get to about 1/20 of a second at ISO 100 before the highlights start getting blown out in broad daylight.
Introducing: the neutral density filter!
Jasper National Park, Alberta // Photographer: Jason Wilson // Sony a7R II + Metabones Adapter + Canon 24-70mm f/2.8L II // ISO 200, f/8, 30" // Lee Filters 10-Stop Neutral Density Filter
Mission, British Columbia // Photographer: Jason Wilson // Canon 5D Mark IV + Canon 24-70mm f/2.8L II // ISO 320, f/5.6, 1" // Lee Filters 6-Stop Neutral Density Filter
There are a wide array of different filters that can be added to the lens for different effects, but what you want in this case is called a "neutral density" filter. This addition will simply diffuse the amount of light passing through the lens, allowing less to hit the sensor; in turn giving the camera the capability of longer exposures in situations with more light (such as bright, sunny days) without blowing out the image highlights. It will also allow you to shoot wide open apertures such as f/1.4 without overexposing.
There are two types of neutral density (ND) filters to consider: full panel and the graduated. Full panel ND filters will eliminate the same amount of light across the glass, while graduated ND filters will eliminate a certain amount at one end, gradually fading to a different amount on the other end. This is handy when shooting into direct light sources such as a sunset. Next time you take a photo of a sunset, notice how either the sun and sky can be perfectly exposed, or the foreground can be perfectly exposed... But not both in one photo. This is because the camera cannot compensate for such a wide Dynamic Range (DR) of light without assistance from an ND filter. If you were to add a graduated ND filter that allows less light in at the top of the image (such as the sky at sunset) and more light in the shadows (such as the beach below the sky) then you can get a well-balanced image.
The shots above were taken with a full panel ND filter. It allowed me to capture the detail and color that I wanted over a longer exposure for a longer duration of time, therefore introducing the movement of the waterfall. ND filters range from very subtle (ND.3) which eliminates 1 stop of light, to strong (ND1000) which eliminates 10 stops of light. The increase in the ND "number" directly correlates with the amount of light-stopping power.
There are two ways to attach filters to your camera lens:
1. Screw-in system: Many filters will have the ability to screw directly onto your camera lens' existing threads. A few advantages of the screw-in system include not allowing any additional light to enter the lens through the mounting threads, no need for adapters, lower cost, lighter and less bulk. A few of the disadvantages include the potential for more vignetting, the need for a specific size to match the thread of each individual lens, and difficulty adjusting the angle for graduated ND filters.
2. Slot-in system: An adaptor is fixed onto the lens, and various filters can be placed into a number of slots fixed on the adapter. A few advantages of the slot-in system include the ability to work on any lens, minimal vignetting, ability to utilize multiple filters at one time, and the easy position adjustment of graduated ND filters. A few of the disadvantages include purchasing a required adapter ring, generally higher cost, larger size and weight, and the potential for light to enter through the side of the adapter if not attached properly.
I personally use a set of Lee Filters, including their well-known "Big Stopper" 10-stop ND, and it's little brother, the "Little Stopper" 6-stop ND, along with varying graduated ND filters for landscape images.
Laguna Beach, California // Photographer: Jason Wilson // Canon 5D Mark III + Canon 16-35mm f/2.8L II // ISO 160, f/4, 30" // Lee Filters 10-Stop Neutral Density Filter + .9-Stop Hard Graduated Neutral Density Filter