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Simplify exposure, three main elements work together for this purpose.

Skunk cabbage "Symplocarpus foetidus" flowers bloom in late February or early March.
Skunk cabbage "Symplocarpus foetidus" flowers bloom in late February or early March.
Photo by Bill McCracken


Spring is not far away when skunk cabbage emerges through the snow. Large patches can be found at the Prairie Oaks Metro Park in western Franklin County. In this exposure notice the depth of field and color. Choose the right exposure for the best results.
The three elements that make up any exposure are shutter speed, aperture, and ISO. They change with lighting conditions to make images darker or brighter.
Shutter speed controls the amount of time light is exposed. An example would be the picture of a bird eating; shutter speeds of 1/250 and greater are needed to stop the movement. Another example would be to allow moving water to have a dreamy milky texture requires a slow speed 1/15 or slower.
Aperture controls the amount of light exposed in the exposure and depth of field. An example of this would be f/4.0 results in a brighter image but has less depth of field. A flower would be properly lighted but less of it would be in focus. The aperture of f/22.0 will allow less light in but has greater depth of field. The same flower would be properly lighted but now has more in focus.
The ISO controls the sensitivity that the film or chip records in. An example would be to stop action by changing the ISO from 200 to 400 with an aperture of f/16.0. The ISO 200 shutter speed is 1/30 and the ISO 400 shutter speed is 1/60.
This relationship of the three elements is fundamental in understanding how to use light in any situation. The light can be natural, artificial, or any combination and the relationship still works.
Digital cameras allow a preview of the image as they are taken. The cameras have a histogram that shows a graph of the mid tones, highlights, and shadows in the image. This tool is the best way to see the effect of changes in exposure.
The path to a successful image lighting combination is proper metering, selecting the right combination, and setting up the camera to do this.
The next article “metering the exposure” will explain more.
The exposure for this image is the shutter speed 1/6sec, aperture f/18, ISO 100, exposure program manual, and white balance fine weather.

http://www.photoxels.com/tutorial_exposure.html

http://www.photohead.com/exposure/slmcam.php

http://www.luminos-landscape.com/tutorials/understanding-series/understanding-histogram

 

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