Easy Basic Photography
as the pupils in our eyes expand and contract depending on the amount of light around us, the aperture opening of a camera lens can be made wider or smaller to let in more or less light as it is needed. In general, the less available light there is, (and depending upon the Shutter Speed and ISO) the wider the aperture opening will need to be to obtain an acceptable exposure. The aperture size is adjusted in numbered increments called F stops. The range of F stops will vary depending on the lens. A common range of F stops found in Digital Slr cameras would be from F2 which would be the widest opening, to F16 which would be the smallest opening. The aperture setting can be changed when you are using a Digital Slr (Digital Single Lens Reflex) camera or certain Bridge/Advanced compact cameras. The aperture setting can be controlled by using the manual or aperture priority modes. The and the are examples of Digital Slr cameras with manual and aperture priority modes for controlling the aperture settings. However, if you are using a basic compact camera, you will not be able to change the aperture settings. The camera will automatically change the aperture settings for you. Lens Aperture Chart Here is a list of some standard F stops: Although it might seem backward, each larger F stop number allows half as much light into the camera as the one before it. On the reverse side, each smaller F stop number allows twice as might light in the camera as the one that comes after it. If that seems confusing, check the above diagram showing aperture opening sizes and try looking at it this way: F4 allows half as much light into the camera as F2.8 F16 allows half as much light into the camera as F11 F5.6 allows twice as much light into the camera as F8 F2 allows twice as much light into the camera as F2.8 Each of the F Stop numbers listed in the chart above represent one full stop. However, many cameras will have F Stops shown in 1/2 or 1/3 increments. Below are aperture charts showing the F Stops in 1/2 and 1/3 increments. F Stops in 1/2 stop increments: F Stops in 1/3 stop increments: The maximum aperture opening (width) for a lens such as F2.8 is usually listed on the barrel of the camera lens. On a zoom lens, it is listed as a range. (eg. F4 to F11). Why is the aperture important?: As previously mentioned, the aperture allows a certain amount of light to reach the film or sensor so that a correct exposure may be obtained. (in conjunction with the camera shutter speed and the ISO setting). The aperture also controls the Depth of Field in a picture. Depth of Field is a term that refers to the range of how much of the scene in a picture will be in or out of focus. Take a look at image #1. Only the budding plant is pretty much in focus while the background grass and leaves are out of focus. That is called narrow depth of field. Next look at image #2. The yellow flower as well as the red flower in the background and the grass leaves are all in focus. This is called wide depth of field. Using an aperture setting such as F2.8 will yield an effect similar to image #1. Using a smaller aperture setting like F8 will yield results more similar to image #2. Please see the tutorial on depth of field for more details. Check the Digital Camera Exposure Basics tutorial to see how the aperture, shutter, and ISO settings work together to produce properly exposed images.. |
The Camera Lens Aperture
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Image #1 Image #2
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