Mastering Photo Exposure – The Exposure Triangle
There are three basic elements on a camera that effect the exposure of an image. Together, these three facets are known as the exposure triangle.
– the measure of a digital camera’s sensitivity to light
– The size of the opening in the lens when a picture is taken
– the amount of time that the shutter is open.
The exposure of your photograph is wherever these three intersect. A change in just one of these three things affects the others. You will always be working with three of these if you are working with one.
Various people portray the relationship between ISO, Aperture and Shutter Speed using differing representations to help us understand. Here are three of the most common. These are far from exact and are just for illustrative purposes:
Think of your camera as a window with closing shutters.
Aperture is the actual size of the window. The bigger the window, obviously, the more the light that is allowed to enter the room, and the room is therefore brighter.
Shutter Speed is the measure of time that the shades of the window are open. The longer the shades are open the more light comes in. If you open and immediately close them, then little light is allowed in.
if you were in the room wearing sunglasses, your eyes get the chance to be desensitized to the light that comes in (it takes after a low ISO).
There are different strategies for rating the measure of light in the room. You could extend the time that the screens are open (lower shutter speed), you could make the window larger (like raising the aperture) or you could take off your sunglasses (make the ISO greater).
Another way to think of exposure is to get a sun tan.
One may say your skin is sort look like an ISO rating. Some peoples’ skin is more sensitive to the sun than others.
Shutter speed is like the amount of time you spend out in the sun. The more you spend in the sun the more chances of you getting a tan (if you stay out too long you may be “overexposed” and get burned).
Aperture is like sunscreen which you apply to your skin. Sunscreen obstructs the sun at different rates depending on it’s quality. Apply a top notch sunscreen and you reduce the measure of light that overcomes – and along these lines even a man with extraordinarily delicate skin can spend more time in the sun (ie decrease the Aperture and you can cut back shutter speed and/or lessen ISO).
A third similarity is the Garden Hose (the width of the hose is aperture, the length that the hose is left on is shade speed and the heaviness of the water (the pace it moves beyond) is ISO.
Mastering the exposure takes practice. Even experienced photographers are always changing settings in an effort to try different things and find the perfect combination. Keep in mind that changing each segment influences the presentation of the photo and also has an impact upon the various parts of the triangle (ie changing aperture changes depth of field, changing ISO changes the graininess of a shot, and changing shutter speed influences how motion is captured).
The significant thing about digital cameras is that they are the ideal testing ground for getting some answers concerning exposure. You can take any number of shots as you like to no detriment and they not simply allow you to shoot in Auto mode and Manual mode – moreover they generally have semi manual modes like Aperture Priority and Shutter Priority modes which allow you to answer questions about a few parts of the triangle and let the camera handle substitute segments.
Here is a video from Adorama that explains the Exposure Triangle as well.
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