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 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:
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:
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.
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.
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.
Try to find a position that provides a simple background that does not compete with your subject. See examples below.
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.
Exposure - Shutter Speed
Fast shutter speed:
School of fish - Ed Ziegler (2007 Photo competition grand prize winner)
River Otter shaking off water - Mike Baker (2009 Photo competition winner - 1st place Animal Behavior)
Slow shutter speed:
Waterfall photo - Scott Hotaling ( 2007 Photo competition winner - 1st place Peaks, Valleys & Plains)
Red wolf - Jill Vitas (2006 Photo competition winner - Honorable Mention Mammals)
Exposure - Aperture
Depth of field:
Cinnamon fern - David Blevins (2007 Photo competition winner - 1st place Wild Plants)
Winter sunrise - Scott Hotaling (2009 Photo competition winner - 1st place Peaks, Valleys & Plains)
Rule of thirds:
Duck hunter and dog - Melissa McGaw
Cottonmouth - Melissa McGaw
Dragonfly - Johnny Hill (2007 Photo competition winner - 2nd place Invertebrates)
Indigo bunting - Ed Erkes (2006 Photo competition winner - 2nd place Birds)
Greater yellowlegs, Rachel Carson (2009 Photo competition winner - 2nd place Birds)
Beetle tracks - Tom Gillespie (2007 Photo competition winner - Honorable Mention Invertebrates)
Putting out decoys - Robert Handson (2006 Photo competition winner - 1st place Outdoor Recreation)
Oystering - Melissa McGaw
Wild horses - Wesley Gubitz (2009 Photo competition winner - 1st place Mammals)
Maple leaves - Nate Bacheler (2006 Photo competition winner - 1st place Wild Plants)
Chinese Mantid - Ellen Devenny (2007 Photo competition winner - 1st place Invertebrates)
Queen Anne's Lace - Ellen Devenny (2007 Photo competition winner - Honorable Mention Wild Plants)
Man and dog on beach - Regina Chayer - (2009 Photo competition winner - 1st place Outdoor Recreation)
Water lilies - John Stroud (2006 Photo competition winner - 2nd place Wild Plants)
Royal terns - Alexandra Houston (2009 Photo competition winner - Honorable Mention Birds)