One of the three options you have for a metering pattern, or the area in the viewfinder where the metering system takes its information to calculate an exposure, is known as “spot.” The spot options generally takes its information right from the center of the viewfinder and is often defined by a small, etched circular pattern. Some Custom Functions allow you to define the exact circumference of the spot area or move the spot to match a focusing point.
Because spot metering is quite exclusive it does require that you occasionally use it in conjunction with exposure compensation. Like all metering it converts what it reads to a middle gray, so if you meter a white area and want it to record as white you have to add exposure to the reading; conversely if you meter a very dark area and want it to stay dark as seen then you have to take away exposure.
The best way to add or subtract exposure when using a spot meter is to use the exposure compensation feature. You can preset this at +1.5 when, for example, shooting on a bright snowy day and reading from the brightest areas. This should insure that you get texture in the bright white (although it still might shadows areas to become underexposed.)
Spot metering also aids in making readings from smaller areas within the scene, such as a backlit face. In that case no compensation is required.
The easy rules for spot are:
When you spot bright white add exposure (usually +1 or +1.5EV) if you want to render it bright white in the recording.
When you spot a color you will saturate that color.
Text and photo Copyright George Schaub 2010
To saturate the bright yellow and red here all it takes is placing the spot pattern on the color and locking exposure.
