with subjects or objects of interest in the central part of the image. Some cameras allow the user to adjust the weight/balance of the central portion to the peripheral one. If the camera allows a user to move the focus point off the image center, metering will occur around the new focus location. Although promoted as a feature, center-weighted metering was originally a consequence of the meter reading from the focusing screen of SLR cameras. Light scatter from the focusing screen and proximity of the meter cell caused less sensitivity at the edges. Average metering In this metering mode, the camera uses light information from the entire scene and creates an average for the final exposure setting, giving no weighting to any particular portion of the metered area. In some situations, such as a snowy landscape, this mode will result in underexposure by 2 f-stops or more, because the metering system attempts to darken an excessively bright scene. Partial (selective) metering This mode meters a larger area than spot metering (around 10–15% of the entire frame), and is generally used when very bright or very dark areas on the edges of the frame would otherwise unduly influence the metering. As in spot metering, some cameras can use variable points for readings or use a fixed point in the centre of the viewfinder. Multi-zone metering This mode is also called matrix, evaluative, honeycomb, segment metering, or esp (electro selective pattern) metering on some cameras. This metering mode was first introduced by the Nikon FA and was termed Automatic Multi-Pattern metering. On a number of cameras this is the default or standard setting. The camera measures the light intensity in several points in the scene and then combines the results to find the setting for the best exposure. The method of calculation can be different from camera to camera. The actual number of zones used varies widely, from several to over a thousand. The design concept behind multi-zone is to reduce the need to use exposure compensation. Many manufacturers keep their exact calculation methods confidential as proprietary information. A number of factors are taken into consideration, including: autofocus point, distance to subject, areas in or out of focus, colours/hues of the scene, and backlighting. Multi-zone tends to bias its exposure towards the autofocus point, thus ensuring that the point of interest has been exposed for properly. A database of thousands of exposures