Understanding Exposure Metering Modes

The post Understanding Exposure Metering Modes appeared first on Digital Photography School. It was authored by Kevin Landwer-Johan.
Your camera’s metering modes vary the way it measures the light. This affects the way exposure information is provided. Every modern camera has a built-in exposure meter. Sometimes it’s also referred to as a light meter.
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Understanding how to control the exposure metering modes on your camera allows you to take better photos. If what you are photographing contains very little contrast, your camera will make a good exposure in the default mode. When you compose an image with contrast, your camera may not make the exposure you want it to.
Selecting the best metering mode allows you to take more pleasing photographs.
There are three basic exposure metering modes on most cameras. These are:


Choosing the most appropriate mode is a matter of choosing your main subject and making the right settings accordingly.
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How do different exposure metering modes work?
1. Averaged
This mode is named differently depending on the brand of camera you use. Nikon calls it Matrix Metering. On Canon cameras, it’s called Evaluative Metering. Sony and Pentax use the term Multi-Segment Metering. Olympus calls it Digital ESP Metering. Each manufacturer has different algorithms to determine the outcome. Essentially they all do the same thing.
The camera partitions the viewfinder into zones and measures the light in each. It compares these light readings. Then it averages all the information to provide what it decides is the best exposure setting.
Most cameras have this mode as the default. This is how my camera is set most of the time. Using this mode will give you an overall idea of what your exposure settings need to be. When the light is fairly even, using this exposure meter mode works well.
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2. Spot
Using this mode, your exposure meter will measure the light from a small area – usually about 3.5% of the frame. You need to place the spot exactly where you want to take your reading from. This will most often be your main subject.
The position of the spot within your frame varies from camera to camera. In some cameras, the spot moves with the point of focus. On other cameras, it remains fixed in the center of the frame. It’s important you know where your spot is, otherwise your exposure can be incorrect. Consult your camera manual or do an online search to find how your camera’s spot meter is positioned.
3. Center-Weighted
This mode reads the light from an area in the center of your frame. The percentage of the area varies from camera to camera. It is typically around 60%. Some camera models allow you to vary the area it covers. This mode is good if you compose with your subject in the center. I rarely compose that way, so never use this mode.
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How to use the Exposure Meter
Half-pressing the shutter release button activates the exposure meter. It will turn off automatically after a time. So if you are not seeing the information it provides, it may have switched itself off.
In your viewfinder or on the monitor you’ll see the information displayed like this on most cameras.

Sony cameras use numbers and the and – symbols to display the exposure information.
If you set your camera to manual exposure, you will see the information displayed when the meter is on. When in an auto mode this information may not be displayed. This is because the camera determines the exposure.
Using manual mode a ‘0’ in the display indicates when the exposure is correct. When the display shows a row of dots stretching towards the – symbol, your image will be underexposed. When the display shows a row of dots stretching towards the symbol, your image will be overexposed.
Using this information, you can make the required adjustments to your aperture, shutter speed, and/or ISO.
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Why are there different Exposure Meter Modes?
Photographs are captured by digital cameras recording reflected light. Light and the tone of your subjects is variable. You need to set your exposure according to how bright or dark your subject appears.
Making a composition with very little tonal variation when the light is flat, your camera will easily make a correct exposure. When there’s high contrast, particularly when the light is harsh, it can be more difficult to get a correct exposure.
In high contrast situations, it’s important to manage your exposure meter. You must read the light from the most important area of your composition. Choosing Averaged or Center-Weighted Metering can often result in poorly-exposed photographs.
Spot metering is most useful when you’re photographing a composition where there’s a lot of contrast. Taking a spot meter reading from the main part of your composition will allow you to expose it well.
Portrait photography is one example of when it’s helpful to switch your metering mode to spot. The face of the person is normally the most important part of your composition. You want the person’s skin tone to be exposed well.
By placing the spot meter on your subject’s face and taking a meter reading, you can adjust the exposure accordingly. If you are using an Auto Mode, your camera will make the setting adjustments for you.
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Using spot metering on a camera when the spot is fixed in the center of the frame, you need to point it where you want to take the reading from. Using an Auto Mode when you recompose to frame your subject, you’ll need to hold the exposure lock button.  If you don’t lock the exposure, your camera will readjust the settings. In Manual Mode, the settings remain constant until you change them again.
Illustrative examples
Photographing a person against a dark or light background requires careful metering so their skin tone looks natural.
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Here’s a portrait of Masu. She is a Kayan woman living with her family in Thailand. I positioned my spot meter to take a reading from her face. In this case, my exposure setting was 1/640th of a second at f/4 and my ISO was set to 400.
If I had used Averaged or Center-Weighted metering, my exposure would have been incorrect. The camera would have accounted for a large portion of the black background.
Placing the spot meter on her face was important. If I’d left the spot in the center of the frame my reading would have been incorrect. It would have read the light reflecting off the black. This would give a reading which would have led to an overexposed skin tone.
© Kevin Landwer-Johan
With Masu standing against the white background, I made my exposure metering the same way. The settings are identical to the settings I used for the black background. This is because the light had not changed, only the background.
Choosing the right exposure metering mode helps you better control your exposures. It’s important to look at the light and tone in your composition. Then determine the most important area to expose for. The more contrast there is, the more important it is to meter well.

The post Understanding Exposure Metering Modes appeared first on Digital Photography School. It was authored by Kevin Landwer-Johan.

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