The meter in your camera may be part of the most advanced metering system available, yet it cannot be considered accurate all the time. This is not because of a technological shortfall, but because of a simple principle: your camera’s meter is designed to meter for reflected light and reflected light varies according to the surface colour or tone.
Quite simply, black surfaces will reflect less than white surfaces. Coloured surfacesalso reflect light according to their tone. For this reason, TTL camera meters aredesigned to meter at 18% grey. In other words, they assume everything youphotograph is a mid grey. However, there are few scenes where the colours, thehighlights and shadows blend perfectly into an 18% grey.
Of course, reflected light readings can be useful but you are wise to consider using the metering options that many of today’s cameras offer. There are three types of inbuilt metering options available in many cameras today, especially digital SLR cameras. The most commonly used is usually a full frame, multi- pattern type metering which meters the entire scene and divides it into sections, allowing the camera’s computer to come up with the best exposure.
However, there are usually two other types available and they are centre weighted metering and spot metering. While we are not normally encourage to compose with our subjects in the centre, this kind of metering nonetheless often finds its value in exposing for scenes in which the centre is the most important part. These may be landscapes, group photography, and family snaps. Centre
weighted metering is exactly as it is called.
The exposure that it determined by the camera is biased toward the light reflected from the centre of the scene. Then, there is spot metering. This is where many photographers live. Spot metering can be used to determine the correct exposure for the most important part of the scene, or for
taking an exposure reading from something within the scene that has a mid tone. Remember though that spot metering is based upon reflected light so shadow and highlight areas that are spot metered can also fool the camera.
Wedding portrait photographers use spot metering all the time. Brides in white and grooms in black will naturally present a problem for camera metering systems, and problems can occur if you solely rely upon a camera’s meter for accurate exposures. Spot metering allows you to meter for the areas in the photo that you wish to properly expose. You may also meter for several small sections
of the scene and select an exposure setting that allows for detail in both highlight and shadow. It also allows the photographer to select and meter for a part of the frame that is close enough to a mid grey.
Accurate metering is essential for excellence in your images. This is especially true of digital images. Correct exposure means less time taken on the computer, and better images in print. If your camera offers you these metering options, be sure to use them. At first you may find it interesting to experiment, but eventually you will be able to select the best option for each of your photographic Image as metered by the camera situations.