The Exposure TriangleEquipped with the knowledge of the "Exposure Triangle," students will be able to elevate the level of sophistication of their photography. The three components of the Exposure Triangle will allow students to achieve the ideal exposure. It is critical for students to familiarize themselves with Lens Aperture, Shutter Speed, and ISO Sensitivity (film speed).
Explanations of each of the three components of the Exposure Triangle are listed below. |
Lens ApertureThe aperture of a lens is used to regulate the amount of light that passes through the lens and reaches the camera's sensor. The aperture controls the diameter of the lens opening and is measured in a numeric notation referred to as an f-stop. The larger f-stops (f/22) have smaller apertures which let in less light than the smaller f-stops (f/1.8) that have wider apertures. The aperture also assists in controlling the depth of field or how much of the photograph is sharp or in focus. When you are using smaller apertures (larger f-stops), more of your photograph will remain in focus. Conversely, when using wider apertures (smaller f-stops), less of your photograph will remain in focus, thereby giving you a more shallow depth of field.
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Shutter SpeedThe camera's shutter speed determines the amount of time that the shutter remains open. Along with the lens aperture, the shutter speed regulates the amount of light that reaches the camera's sensor. The different shutter speed settings are represented in a numeric fraction of a second. The smaller the numeric fraction (i.e. 1/500 vs. 1/60), the smaller the amount of time that the shutter is open. Faster shutter speeds are ideal for capturing moving objects (birds in flight or moving cars). Slower shutter speeds are ideal for stationary objects in lower light OR for intentionally blurring moving objects. The rule of thumb for minimum suggested shutter speed is that the shutter speed should be greater than or equal to the reciprocal value of your given focal length.
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ISO (film speed)ISO sensitivity is the final component of the exposure triangle. While not as major of a player as aperture or shutter speed, ISO sensitivity can assist in capturing an ideal exposure. The camera's ISO sensitivity (or film speed) refers to the setting on the camera that controls the camera's sensitivity to light. Depending on the light conditions under which you are shooting, you will need to adjust your camera's ISO level accordingly. If you are outdoors on a sunny day, you will not need to set your ISO very high (not much higher than 80 or 100). However, on a cloudy day or in a dimly lit interior, you may (and probably will) need to increase the camera's ISO setting. It is very important to note that while it may help compensate for low lighting, increasing the ISO setting will increase the graininess and/or noise in your photographs. In the end, increasing the ISO should be regarded as a last resort.
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