TRY it! You'll be amazed at how simple animations can make even the most difficult concepts easily understandable. Now in two of our eTexts and soon to be in all.
Here are just some of the 90 animations, those on the topic of exposure. Just click the links below.
Many PhotoCourse.com textbooks are now supported with integrated interactive multimedia. Our eTexts include clickable links that display animations and other resources stored on the PhotoCourse.com Website. To view them you need an Internet connection. These animations and other resources are designed to help you better master your camera. If you have an eText, just click any button that looks like the ones to the left. The animation that is played is related to the digital photography concept discussed on that page.
Understanding Exposure
The amount of light that strikes the image sensor determines how light or dark the captured image is. As the sensor gathers more light, the image becomes lighter. There is only one point, or perhaps a narrow range, where it is perfectly exposed.
Aperture-Shutter Speed Equivalents
There is often more than one aperture-shutter speed combination available that gives the same exposure. As shown here by the pairs connected by the red line as the aperture gets larger to let in more light, the shutter speed gets faster to keep the exposure constant.
Changing Exposure Modes
Most digital cameras have a mode dial that you turn to select an exposure mode. Here are those offered on many Canon cameras.
Shutter Speed Effect on Exposure
Fast shutter speeds let in less light, and if the aperture doesn’t change, as the speed gets slower it lets in more light and the picture gets lighter.
Shutters
How a Focal Plane Shutter Works at Fast Shutter Speeds. At fast shutter speeds the focal plane shutter curtains move across the image sensor as a slit "painting" the image as it goes.
How a Focal Plane Shutter Works at Slow Shutter Speeds. At slower shutter speeds there is a point at which the entire image sensor is exposed to light. The first curtain opens completely and only then does the second curtain start to close. The fastest shutter speed at which this happens is called the flash sync speed.
How an Electronic Shutter Works. An electronic shutter turns on the image sensor to begin recording the exposure and turns it off to end it. In between those two points the image builds up as light is captured by the sensor. Because these shutters have no moving parts they are less expensive. However, they can also be very precise and accurate in more expensive versions.Shutter Speed Effect on Motion
The speed of the subject determines which shutter speeds freeze or blur the action. When trying to freeze action, the faster the subject is moving the faster the shutter speed must be.
Apertures and Their Effect on Exposure
Apertures Effect on Exposure. Smaller apertures let in less light, and if the shutter speed doesn’t change, as the aperture gets larger it lets in more light and the picture gets lighter.
Aperture and Depth of Field
As the aperture gets larger, the depth of field gets shallower and objects in the foreground and background become softer. Here the camera is focused on the gray building so that's where the plane of critical focus is. As the aperture is opened one stop at a time, the depth of field in front and behind that plane gets shallower and shallower.
How Your Meter Sees
The exposure meter in your camera doesn't see the same detail you see. It sees only averages, as if you were looking at the scene through a sheet of frosted glass.
Exposure Compensation
Exposure compensation lightens or darkens a picture by increasing (+) or decreasing (-) the exposure.
Exposure Lock
You can lock exposure (and focus) on any part of a scene just by pointing the camera at it and pressing the shutter button halfway down. Without releasing the shutter button, you then compose the image the way you want it, and press the shutter button the rest of the way down to take the photo.
Autoexposure Bracketing
Automatic exposure bracketing (AEB) automates exposure compensation by letting you take 3 or 5 photos while the camera automatically varies the exposure for you.
Histograms
Highlight Warnings. Many cameras will display a highlight warning when you review your images. Areas of the image that are pure white, without any detail, blink or are outlined in color. Skies are often pure white but the only areas on an image that should always be like this are spectral highlights such as reflections.
