Understanding Camera Metering

Metering For The Right Exposure

Correctly metering an exposure is key to getting successful landscape photographs. The contrast between the lightest and darkest areas in a landscape can be vast, especially when shooting at sunrise or sunset. This difference in brightness range is often too great for either film or digital sensors to cope with, even with the help of filters, so you need to work at getting the exposure right each time.

The metering system in your camera measures the amount of light in the photo and tells you the aperture and shutter speed needed for a correct exposure.

The fact is, though, that you can’t always rely on your camera’s built-in meter to get the exposure right. But you can increase your success rate by selecting the right metering mode for the conditions. Not all cameras (even SLRs) allow you to select the type of metering to use. But the explanations below will help you understand how your camera measures light. Your camera manual will explain which metering modes your camera uses under different settings.

Multi-Segment Metering

This is also known as evaluative or matrix metering and is the most sophisticated of the in-camera metering modes. The camera splits the scene into a number of segments – how many and their shapes are decided by the camera manufacturers. These segments are measured individually and the camera then analyzes the readings and calculates the optimum exposure.

Each camera manufacturer has their own secret way of processing the information to produce a final exposure, but most use a set of typical scenes as a basis.

Multi-segment metering is best for point-and-shoot photos as it’s the most likely to get the exposure right for a wide range of scenes. It can still be fooled by very dark or very bright scenes (like snow-covered landscapes) and it’s difficult to predict how the meter will react in these conditions.

Center-Weighted Average

Centre-Weighted Metering

This is one of the simplest metering systems around. A center-weighted meter takes an average reading across the whole frame but takes most of the reading from the center of the image.

Many landscape photographers prefer center-weighted metering to multi-segment because it’s more predictable. There’s no in-camera processing so it’s easily fooled by very light or dark scenes but, with practice, you can soon learn how much exposure compensation you’ll need to apply for different conditions.

Many cameras only offer this metering mode in the Manual mode where the extra control allows you to fine-tune the exposure.

Spot Metering

A spot meter is the most accurate of all the exposure systems as it takes a meter reading form a small area of the frame. It’s also the hardest system to get to grips with as you have to select the right area of the scene to take your reading from. By excluding bright and dark areas, you can set the exposure accurately.

Most cameras use the center of the frame to spot meter from but some more expensive cameras meter from the area around the autofocus point.

Handheld Light Meter

Even though today’s cameras provide sophisticated metering options, using a handheld light meter still offers the ultimate in exposure control.

When shooting landscapes, your camera will often be fixed to a tripod.

If you’ve framed your perfect composition, you won’t want to move the camera but your camera’s metering can only work from the scene your camera is pointed at and so may not give an accurate exposure reading.

This is where the handheld lightmeter comes into its own. You can leave your camera pointing at your scene while directing the light meter at whatever point you want. Some models also provide a spot metering option.

How To Use a Lightmeter

It’s simple. Point the meter at your subject and take a reading. This what is known as reflective reading. Just like the meter built into your camera, this method can be fooled into giving the wrong readings when used with very dark or bright scenes.

So how do you get around this limitation?

Handheld meters have a white “invercone” (as it’s called) that can be placed over the sensor. Once this is in place, you can get an accurate reading for the light falling onto the scene.

This gives the most accurate results but you have to place the light meter where the subject is (which may be difficult for a landscape!) and point the sensor back towards the camera to take the reading.

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