Apertures and Shutter Speed
By F.M. Kearney
Perhaps you were intrigued by the photos you saw in magazines. Maybe you wondered why your own photos never came close to matching them, or even the scene you just photographed. It might simply be that you’re just curious about the purpose of all those strange-looking buttons and dials on your new camera or lens. Whatever the reason, you’ve decided to get a little more serious about photography and you’re interested in elevating your skills to another level. If that’s the case, then this article was written just for you.
Today, photography is easier than it’s ever been. The quality of the latest digital cameras and cellphones make it possible for amateurs to capture photos almost as good as the pros. I’ve heard of stories where some wedding photographers are finding it harder and harder to find work because the wedding guests can shoot near-pro photos with their phones… for free! Indeed, the technology has come a long way. The auto everything, “set-it-and-forget-it” technique will work fine up to a point. But if you want your photos to reflect your vision and not your camera’s, you will need to learn the basics of photography.
If you’re interested in photography, you’ve probably heard a lot of strange terms being thrown around, i.e., depth of field, focal length, shutter speeds and apertures, just to name a few. It can be a bit overwhelming, and at times, even sounding like another language. But, as with most things, it’s much easier to digest if taken in small doses.
Photography is all about light. In fact, the word “photography” literally means “drawing with light.” An exposure is made when a digital sensor (or film) is exposed to light. The way in which a camera and lens manipulate light is how a correct exposure is made. The camera controls the duration of time the sensor is exposed to light via its shutter – a small window inside the camera that opens and closes in front of the sensor. The speed at which it opens and closes is called the shutter speed. The amount of light entering the lens is controlled via its aperture – an adjustable diaphragm with set openings of various sizes called f/stops. The most common shutter speeds are measured in fractions of a second, i.e., 1/30 second, 1/60 second, 1/125 second, etc. However, depending on the situation, they can range from several seconds to several hours. Aperture settings, or f/stops, are designated as f/22, f/16, f/11, f/8, f/5.6, f/4, f/2.8 and f/1.8. Depending on your lens, you may have more or less f/stops, or f/stops that vary slightly from these, but the ones listed here are the most commonly used. If you’re curious, the “f” stands for focal length and the numbers are derived by dividing the focal length of the lens by the diameter of the lens opening, but… that’s getting WAY ahead of ourselves! In fact, it’s not something you really need to know in order to understand photography.
Whenever I try to explain shutter speeds and apertures to beginners, I like to use the best camera in the world… their own eyes. Sometimes, I think it’s easier to understand something if you personally experience it, rather than read about it or have someone tell you about it. To illustrate shutter speed effects, I’ll take them to a place bustling with activity – like a busy street. I’ll tell them to close their eyes, then, open and close them again really fast. When I ask them what they saw, they may say such things like: people, cars, trucks and buses. I’ll ask them to open and close their eyes again, but to keep them open for about a second. This time, they tend to get a little more descriptive and say things like: people walking, cars moving, trucks turning and buses letting passengers on and off. A quick blink only revealed a frozen snapshot in time, but they were able to detect a lot more activity when they kept their eyes open longer. This is exactly how the shutter in your camera works. A fast shutter speed (the blink of an eye) essentially freezes motion, whereas, a slow shutter speed (holding your eyes open for a longer length of time) reveals more motion. The only difference is that the camera will record this motion as a blur. Therefore, if you’re trying to freeze the motion of a subject, you need to use a fast shutter speed like 1/500 second or 1/1000 second. Conversely, if you want to show motion (or blur), you need to use a slower speed like ½ second or ¼ second.
The photos above illustrate the different effects you can create with water simply by changing your shutter speeds. 1/60 second practically froze the waterfall, whereas, at 1/3 second, a much longer length of time, the waterfall becomes so blurry that it looks less like water and more like a silky fabric.
There’s no limit to how slow your shutter speed can be. When it comes to depicting motion, the slower the speed the more surreal your photo will look. I shot the photo at the top of this article at a full 15 seconds. Although there’s not much change in the silky appearance of the waterfall, you can see how much the ripples in the stream have been smoothed out. Super-long exposures with water have a way of revealing interesting patterns that are almost imperceptible to the naked eye. If you look at the base of the falls, you can clearly see an elongated, triangular pattern created by the water flow. You can sort of make it out in the photo (above) I shot at 1/3 second, but it’s much more defined when the length of the exposure is increased. There is no “right” or “wrong” setting. It all comes down to your own vision and personal taste.
Shooting long exposures can be a lot of fun. The patterns and shapes formed by rushing water or billowing leaves can turn out to be a masterpiece… or a mess. As Forrest Gump would say, “You never know what you’re gonna get!” But, you have to be aware of everything that can move during the exposure – things that you might not want to be blurry. Take another look at the photo at the top of this article. Notice the blur on the leaves to the left of the waterfall. The winds were very calm, but even on the calmest of days it’s very hard for leaves to remain completely motionless for 15 whole seconds. I’m actually surprised that the leaves on the right appear as sharp as they do. Lastly, if you think you might want to shoot long exposures, you will definitely need to invest in a good tripod to keep the camera steady.
While the shutter controls the motion of a subject, the aperture controls how sharp the subject appears, or, more accurately, how sharp its surroundings appear. This is referred to as “depth of field.” One of the things that often confuses beginners is that large-number settings like f/16 and f/22 represent the smallest openings, yielding the largest depth of field. Small-number settings like f/2.8 and f/1.8 are the widest openings, yielding the least depth of field. The larger the depth of field, the sharper the area in front and behind your subject is perceived. Conversely, the smaller the depth of field, the more out of focus this area will be. To better illustrate this, once again, I turn to the eyes. Have you ever noticed how your vision gets slightly better when you squint? Light rays enter your eye from all angles, but not all of those rays focused equally. Only the rays that enter at the center of the eye are focused sharply, but the rays entering around the edges are unfocused. When you squint, you’re essentially filtering out the unfocused light rays in your peripheral vision – thus, resulting in better vision. Once again, this is exactly how the aperture in a lens works. As you stop (or close) the aperture down to its smaller settings, you’re letting in less unfocused light that enters around the edges of the lens and your image appears sharper. Keep in mind, the object you focus on will always be 100% sharp, regardless of the selected aperture. What we’re talking about is the sharpness of the area directly in front and behind the subject, a.k.a., the depth of field. I like to think of it as the depth of the field of sharpness.
The photos below illustrate how you can change the look of your images simply by manipulating the aperture. I focused on the second post for both shots. For the image on the left, I opened the aperture up to its widest setting at f/2.8. This reduced the depth of field to just the small area around that post – rendering it as the sharpest post in the row. In the other photo, however, I closed the aperture down to f/16, which increased the depth of field to include almost the entire row.
Once again, the decision to use a shallow or a large depth of field is totally up to you and your vision. There is no “right” or “wrong” setting. Below is another example of how depth of field can change the look and meaning of a photo.
I shot the photo on the left at f/2.8. The shallow depth of field threw the background out of focus – making the Itea bush stand out in this chaotic scene. But, if your goal is to place equal emphasis on the bush as well as the background, you would need to select a smaller aperture like f/11. The increased depth of field renders everything equally sharp.
You will notice that I bolded certain settings for all of the photos in this article. That’s because those are the most important settings in achieving the desired results. If you want to control a subject’s movement, you need to select the appropriate shutter speed. If the sharpness of the foreground and/or background is a concern, you need to control the aperture. If you’re using an auto-exposure mode, i.e., shutter priority/aperture priority, the camera will set the correct corresponding setting.
If you want to get serious about your photography, it’s important to take the time to learn these basics. It all may seem a bit overwhelming at first, but it’s really not that difficult. Actually, I find “amateur” cameras more difficult to understand. I’m often at a loss when friends of mine ask me for help in using their cameras. Conventional aperture and shutter speed settings are replaced by symbols of flowers, mountain ranges, a person running, etc. In my mind, I’m wondering, “What the heck is this!?” You don’t need to be a master photographer or an expert in Photoshop. With just the basic knowledge of how to manipulate apertures and shutter speeds, you can move beyond these symbols and craft images that truly reflect your own vision. You’ll be amazed at the degree to which you can elevate the quality of your photography.
If apertures and shutter speeds still have you scratching your head, just remember your own eyes – they perfectly mimic how a camera and lens operates.
F.M. Kearney began his career as a photojournalist for a variety of local New York City newspapers. It was an exciting profession, which allowed him to cover everything from famous celebrities to ride-alongs with NYPD and FDNY. He now specializes in nature and urban landscapes. To view more of his work, visit www.starlitecollection.com. He can be contacted at firstname.lastname@example.org, or followed on Facebook (@fmkearneyphotos) and/or Twitter (@fmkearneyphoto).