Learn all about Exposure Metering Modes
The first thing you need to master with your camera – besides how to load the memory card – is how to measure the light on the subject that you are photographing. DSLRs have a built-in TTL (Through-The-Lens) light meter, which measures the ambient or reflective light on the subject. The TTL meter needs to become your new best friend when it comes to understanding digital photography and properly exposing a photograph. Mastering this basic necessity will catapult your photos to the next level.
Why is this so important?
So you can accurately represent the image by capturing all the exciting details, colors, shadows and textures. I’m sure by now that you’ve taken an improperly exposed photograph while “experimenting” with your camera (who hasn’t?), and have seen the loss of image information in the highlights. Unfortunately with digital photography once you’ve over-exposed an image, that image information is gone forever. So ignore this at your own peril, or watch your skill flourish.
In this mode, the camera measures the light information originating from the middle of the viewfinder (it also absorbs image data from the rest of the frame, but the computer gives that light less importance). This setting causes the camera to focus on the subject in the middle of the frame and isn’t too influenced by any excessively dark or light backgrounds or sides of the frame. This setting is ideal for when your subject is in the center of the frame, for instance, a portrait, your sleeping cat, or your broken headlight after an accident.
Spot Metering Mode
When you look through the lens of a DSLR there are typically a series of focus points and/or centering marks; these are small, sometimes selectable areas within the frame from which the camera then samples light to determine the exposure – “the spot.” Any light that falls out of the designated spot is effectively ignored during the exposure value calculation. This setting is ideal for when the subject is small within the frame or the lighting on background objects competes with the main subject and you need to zero in on what has captured your eye. Many cameras allow the user to choose which mark is the spot, thus giving you more flexibility and control.
Partial Metering Mode
Partial Metering is a camera-metering mode in which the metering is weighted at the center of the viewfinder (unlike center-weighted in which the camera averages the exposure based on the reading at the center). You can think of Partial Metering as “expanded” spot metering, because the area that is metered is specific, but not tiny (roughly 10% of the viewfinder versus 2.3% of the viewfinder for spot metering mode). Partial metering is best used when your subject is overly backlit and you want to get a quality exposure of the subject. Partial metering will enable correct exposure of your subject, however the background will be over-exposed. Partial metering will enable you to more specifically control the exposure in a particular region of the photograph.
Multi-Zone Metering Mode
Multi-zone metering (also called Matrix, Evaluative metering) is the generic default setting in which the TTL meter uses light from all points in the frame and then the camera makes an approximation as to what’s most important when calculating the exposure value. The effectiveness of the matrix in question has a lot to do with the internal computer and how many matrix points are present (for example 6-point or 9-point matrix). This basic setting is the most non-discriminating and therefore is most useful in situations where the lighting is most uniform – like a landscape – and there aren’t any excessive highlights or dark pockets that could “trick” the sensor.
First examine the picture through the viewfinder. If it looks evenly lit, use the evaluative metering mode. If the person or subject to be photographed has a bright light source like the sun behind them, use center-weighted average metering mode. If your subject is the most significant part of the picture, use spot metering mode - also referred to as ‘partial mode’. Just ensure that you aim the metering mode icon in the center of your camera’s viewfinder- at your subject.
Metering is a crucial function of the camera (although you could always use a hand-held light meter) as it is critical in determining the exposure value – and photography means “writing with light”! Choosing the wrong metering mode won’t botch every picture you snap; however once you’ve mastered the basics of the metering modes, you’ll be able to avoid under-exposed or over-exposed images or weird images with oddly exposed sections.