Understanding Exposure
The rules of exposure are fixed and involve three primary factors: ISO, aperture, and shutter speed. These three things are interdependent on one another. Changing one alters another. Individually, they each also only do certain things. A higher ISO will always create more “noise” (or grain in a film camera) in an image. A smaller aperture will always give more detail, and a slower shutter speed will always cause more blurring. Proper exposure comes from knowing how these three affect each other and then making the right choice for each scene.
Shutter Speed
Shutter speed is the length of time your camera’s shutter stays open when you take a picture.
Shutter speeds control motion. A moving subject will be ‘frozen’ by fast shutter speeds and blurred by slow shutter speeds.
The standard shutter speed sequence on most cameras is marked in seconds and fractions of seconds, with each setting being half the speed preceding it and double the speed following.
For example: 1/60 second is half the time of 1/30 second but twice as long as 1/125 second.
Fast Shutter Speed Examples:
Slow Shutter Speed Examples:
Understanding Exposure - Aperture
Aperture, or f-stop, is the size of the lens opening through which light passes to the sensor (or film with film cameras).
The f-stop controls depth of field. Depth of field is the portion of the photograph from near to far that is in sharp focus.
The standard settings for f-stops on most camera lenses are set in doubles and halves. The usual settings are f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16 and f/22. Each number represents an opening of the lens that is half the preceding number and double the opening of the number that follows. For example: f/8 is an opening that is half that of f/5.6 but twice that of f/11.
Depth of field examples:
Composition:
The “rules” of composition are subjective—they are more like guidelines or suggestions.
Rule of Thirds:
Imagine that your image is divided into nine equal segments by two vertical and two horizontal lines. Try to position the most important elements in your scene along these lines, or at the points where they intersect.
Examples of using the rule of thirds method:
Leading Lines:
When we look at a photo, our eye is naturally drawn along lines. By thinking about how you place lines in your composition, you can affect the way we view the image, pulling us into the picture, towards the subject or on a journey through the scene. Below are examples of leading lines.
Cropping:
Crop your images either by moving physically closer to your subject or using a zoom or telephoto lens to eliminate unnecessary information. This draws the viewer’s eye to the most important element(s) in your image. See examples below.
Camera angle:
For wildlife, try to get at eye level with your subject. See below.
In general, move around your subject to find the most interesting angle. Explore getting down low or try looking down on your subject from an elevated vantage point. See examples below.
Background:
Try to find a position that provides a simple background that does not compete with your subject. See examples below.
Patterns:
Patterns give the viewer’s eye a visually pleasing repetitive shape or line to follow. They can, in and of themselves, become interesting subjects for photographs.