Digital Camera Metering
By Jakob Jelling, Fri Dec 9th

Looking at the most intricate details of the digital camera as atechnologically advanced device a lot of functions come intoplay. Such s a point is that of the digital camera metering.This discussion focuses towards that intention of understandingand knowing the details of the component. Basically speaking themetering system in a digital camera measures the amount of lightin the scene and calculates the best-fit exposure value based onthe metering mode explained below. Automatic exposure is astandard feature in all the digital cameras. All that isrequires to be done is select the metering mode, point thecamera and press the shutter release. Most of the time, thiswill result in a correct exposure. The detailed explanation andanalysis of the entire process is as follows in the next linesof this discussion.

The metering method defines which information of the scene isused to calculate the exposure value and how it is determined.Metering modes depend on the camera and the brand, but aremostly variations of the following three types. Primarily,matrix or evaluative metering. This is probably the most complexmetering mode, offering the best exposure in most circumstances.Essentially, the scene is split up into a matrix of meteringzones, which are evaluated individually. The overall exposure isbased on an algorithm specific to that camera, the details ofwhich are closely guarded by the manufacturer. Often they arebased

on comparing the measurements to the exposure of typicalscenes.

Next comes the center-weighted average metering. This isprobably the most common metering method implemented in nearlyevery digital camera and the default for those digital camerasthat don't offer metering mode selection. This method averagesthe exposure of the entire frame but gives extra weight to thecenter and is ideal for portraits. Another important is the spotor partial metering. The spot metering allows the user to meterthe subject in the center of the frame or on some at theselected AF point. Only a small area of the whole frame ismetered and the exposure of the rest of the frame is ignored.This type of metering is useful for brightly backlit, macro, andmoon shots. Again a lot has been revealed and a lot remains tobe done so, yet the rudimentary foundation of stringfundamentals can be established via the lines of the above linesof this discussion. It is only hoped that the lines get theirtrue respect from the readers of them and users of the digitalcamera to properly deliver the due respect that the digitalcamera metering technique deserves.

About the author:Jakob Jelling is the founder of http://www.snapjunky.com. Visithis digital camera guide and learn how to take better pictureswith your digicam.