2: Aperture, Shutter Speed, and ISO (Exposure); Basic Settings for a Photoset
Though geared toward rock climbing and bouldering photography, a lot of this information can be applied to any type of photography. Also, I am a 100 percent Nikon DSLR (Digital Single Lens Reflex) user. The information provided is universal, though the approaches outlined are Nikon and more exclusively, DSLR specific.
Aperture, shutter speed and ISO (exposure) are all interrelated, though they each affect different aspects of a photo. First I am going to discuss these components, both their effects and their interrelationships, and then I am going to suggest camera settings (or modes) for specific situations.
Aperture:
Physically, the aperture of a camera is the size of the hole between the two pieces of glass. This means a lot when it comes to photography, both for amount of light, which I’ll discuss first and “depth of field” or “degree of focus” (Commonly abbreviated DOF.) Aperture range is a physical property of a specific lens. For example, my Nikon 35mm has a F range from F2.0 – F22.0, while my Nikon 50mm lens has a F range from F1.4 – F16.0. Generally the lowest aperture is listed on the lens (see below.)
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To understand aperture, take one of your lenses, take off both caps and look through the glass. You should see a tiny hole. In the images below, I opened the hole to F5.6 and then F1.4 to better illustrate the opening of the hole. You can (usually) manually adjust the aperture of your lens. For example, if you have a Nikon 50mm F1.4, you can slide the F-ring (you may need to release the slide-guard, see the image below) from the default F16.0 to F1.4. As you adjust the aperture, you can see the “blades” pen and close accordingly. At F1.4, the lens is completely open, at F16.0; the lens is almost completely closed.
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For an automatic camera, the default F-stop is the highest F-number (as shown in the image above). WARNING: Your automatic camera will not function properly in any other physical position. The camera automatically adjusts the F-stop as you or your shooting mode adjusts it. Be sure to re-set the slide guard so you don’t accidentally bump it while shooting, (rendering your camera useless until you figure out what happened, it should say something like EE if you did this.) I have bought most of my lenses specifically for the F range (not focal length/zoom!)
Effects of Aperture:
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Available Light:
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Depth of Field
The first and most obvious effect of aperture is the amount of available light. I will discuss this first. The second and equally important effect of aperture is the Depth of Field. After discussing these, I will suggest applications for different aperture settings.
Available Light: The more light you have, the faster (shutter speed) you can shoot. In some cases, it may be so bright that you need to lower your aperture or “close” the hole. This is common in extremely bright conditions with a particularly fast lens. (“Fast Lens” is lingo for a low physical F stop, for example both 50mm F1.4 and 35mm F2.0 are fast lenses.) If you camera is limited to a max shutter speed of 1/8000th of a second (Nikon D200 and D70), you may have to adjust a 50mm F1.4 lens to F2.8 or F4.0 to compensate.
Unless you are trying to be creative (for example, shooting a night sky, or shooting a waterfall), you generally want to shoot as fast as possible. The photo below was shot on a super bright sunny day. I was shooting at my max shutter speed (1/8000s), which forced me to set my aperture to F1.8 on my 50mm F1.4 lens. As you can see from the photo, I was able to catch an extremely narrow timeframe. Notice the suspended water droplets. I did, however, have a narrow depth of field. We’ll discuss this in the next section.
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Depth of Field: One of the most distinguishing characteristics of my photography is depth of field (also called Degree of Focus or abbreviated DOF.) For my particular style of photography, I generally shoot a rather narrow depth of field. What this means is that one point is in “focus” while other “depths” are blurry or out of focus. This provides a good “focus point” for a photo and often helps express “depth” or “distance” in a 2-dimensional image. The image below demonstrates a narrow DOF. I focused on the subjects hand, and particularly his fingers to express the intensity of his grip.
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The actual or physical “depth” of focus is a complicated matter (for example, 5 inches or 2.7 feet etc.) This depends on both the aperture and the focal distance. There are numerous calculators which do the physical math. This may be ideal for a studio, however, when taking any type of dynamic photo, your focal distance and thus your DOF for a set aperture changes constantly.
For “Depth of Field”, this is one rule of thumb: The closer the focal length, the narrower the depth of field. If your focal length is infinity (taking a photo of a sunset or distant house), the depth of field will generally be quite large. However, if you are close to your subject (several inches or a foot), expect a narrow depth of field. This is something you will learn with experience. Below is a photo which illustrates a narrow depth of field from a game of chess. Note, the lens is at 70mm F4.4, which is a rather high aperture value. However, since the focal distance is so close, the depth of field is narrow.
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Application of Aperture and DOF: As discussed above, the lower the F number, the larger the hole in between the two pieces of glass. This translates into more available light, allowing the photographer to shoot faster. This is ideal for my climbing photography. Direct sun is the worst lighting for photos. I will discuss this later in another article. Generally climbing photos are taken in low light conditions. Also, climbing is a dynamic sport; in order to capture photos without “blur”, one must shoot fast. Hence, I want as much light as possible so I will shoot at the lowest available F value.
Below is an image I took at a climbing competition in North Carolina. I wanted an extremely narrow depth of field, so I used a 50mm F1.4 lens for significantly close shot (I usually use my 10.5mm fisheye or my 18-70mm zoom at 18mm for bouldering photos). As you can see in the photos below, I focused on her hand for one shot and her face for the other. Because I was so close and was shooting at F1.4, an extremely narrow depth of field was achieved. With this narrow DOF, the main focus of the photo (hand if focus) is on her hand gripping the hold. Pretty cool huh? Image if I would have used a slower lens (higher F number = larger DOF), both her hand and face would have been in focus, rendering a rather flat and boring image.
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One important thing to remember when shooting a narrow depth of field is the importance and precision of your focus point. The Nikon D200 has 11 focus areas. You can adjust the focus area to pick your focus point. If you focus on the wrong point, you will screw up your photo! I usually shoot on (c) mode which continuously focuses the camera as the subjects or camera moves. The other options are (s) which focuses once and holds, and (m) which allows the photographer to manually focus the camera. I will discuss this in another article.
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