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Modern cameras are amazing examples of technology. Besides super-fast autofocus and guessless flash metering, exposure functions such as matrix metering have made it possible to tame many complicated picture-taking situations.
What is matrix metering? Why is it so valuable to beginners and more advanced photographers alike to know how to use matrix metering? Is matrix metering foolproof? How do we decide when to use matrix metering?
What is Matrix Metering?
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As we look at what is matrix metering, it helps to also know why it exists in the first place.
Matrix metering on Nikon cameras was first introduced with a more descriptive name. In the early 1980s, Nikon introduced the Nikon FA camera, which was an evolution of their fine semiautomatic FE and FE-2 cameras.
In addition to manual exposure settings and aperture priority automation, the FA had shutter speed priority and program automation. This was in keeping with all of the other major camera makers and their automatic modes.
What was a pretty deal at the time was a change, not in how automation was carried out, but how the metering for that automation was accomplished. Nikon labeled their idea as AMP or automatic multi-pattern metering.
Averaging / Center-Weighted / Spot
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A camera’s meter, whether coupled to automation or not, reads the light value of a scene. In earlier cameras, the meter cell (or sensor) pointed out from the camera like the lens. A better idea was for the sensors to read what was coming in through the lens.
Usually, these sensors read off of the ground glass in the viewfinder, but sometimes the sensor read light reflected from a mirror and eleven directly off of the film plane. A simple method was for the sensor to simply read the brightness of the full scene which meant everything would average out.
A better idea for most photographers was to give priority to the central area of the scene. Though it still averaged exposure, more importance, or weight, was given to that central area, thus the name center-weighted.
A spot meter only reads a small, well-defined area of the scene. In many cameras, this spot was either round or rectangular and could have an angle of view of 12, 5, or 1 degree. The viewfinder usually gave an indication of the size of the spot.
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Multi-Pattern Smart Evaluation
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While center-weighted and spot metering assisted photographers in getting good exposures in difficult to read lighting conditions such as a backlit subject, there are a lot more challenging situations photographers run up against.
Two situations that even using a spot meter isn’t likely to fix are scenes with large areas of white, black, bright, or dark. Since photo meters are calculated for 18 percent gray, a subject of previous articles, anything far away from the middle gray value will be skewed back towards middle or 18 percent gray.
Some matrix metering examples include a day at the beach or on a ski slope. The bright white snow or the bright sand will fool the camera into underexposing everything, resulting in a muddled appearance.
Likewise a scene filled with very deep tones, black or other colors, will result in a muddled appearance the camera tends to overexpose to get back to middle gray.
AMP or matrix metering helped fix these issues with a computing program and several metering cells reading specific parts of the image area.
How It Does It
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Describing what is matrix metering gets easier once we see it’s more than simply reading values, but also evaluating them or running them through a matrix of possible exposure situations.
That’s where the camera electronics come in. A set of parameters that has been pre-programmed into the camera computer memory and the light values of the different metering cell areas of the scene are evaluated to see what exposure compensation could be made in order to get a better exposure.
That’s why Nikon changed the name on their cameras to matrix metering, it compares a matrix of thousands of imaging examples with the values read from the pattern of separate and distinct areas of the view.
Matrix metering on Canon cameras is called evaluative metering because of the camera brain evaluating the light. Matrix metering on Sony cameras is called smart metering, but it all describes the same thing.
When to Use Matrix Metering
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That’s how to use matrix mastering, from a camera’s perspective anyways. When to use matrix metering is the other important thing to decide now we know what is matrix metering.
Almost all of the lighting condition situations we talked about, backlit subjects, large areas of light or dark, anything not corresponding to 18 percent gray, can be adjusted by the photographers themselves evaluating the scene.
But sometimes we just want to take pictures. GreenDot auto mode is a friendly mode for fun photography and the default metering pattern and computation for that mode is usually matrix metering.
Matrix metering can be used in all exposure modes, program auto, shutter priority, aperture priority, and full manual. The calculations done by modern digital cameras are amazingly accurate and many photographers have learned to trust matrix metering just as much as we trust TTL flash and the autofocus systems in our cameras.
Of course, we should also continue to monitor our camera's display to see what it’s giving us, taking over ourselves when it becomes necessary, but multi-pattern metering is extremely sophisticated and accurate.
With this knowledge of what is matrix metering and also when and how to use matrix metering, we can be confident that our exposures will be well calculated, either by letting the camera do it, or deciding for ourselves.