Canon’s iFCL (intelligent Focus Colour Luminance) metering system is used on all its current DSLRs. This takes both colour and brightness information into account, as well as the focus setting.

When you’re using Evaluative Metering in One Shot autofocus mode, the exposure setting is heavily biased towards the active focus point.

So, for example, if you’re using multi-point AF and only one of the points locks onto a target within a scene, the light metering will be based on this point alone.

Evaluative metering therefore works in a different way to a conventional ‘multi’ metering mode that takes all parts of the scene into account.

It works well for subjects such as backlit portraits, where you’re using a single AF point on the face of the person you’re photographing, and you want to capture the correct exposure for the subject, regardless of how much the background is overexposed.

In other situations, however, the metering can be thrown if the AF point that achieves autofocus falls on a particularly light or dark part of your scene.

To take full control and get more consistent results in tricky lighting conditions, it often pays to switch to one of the other metering modes available on your Canon DSLR.

Centre-weighted average uses the central region of the scene as the main basis for light metering, but also takes the periphery into account to a lesser degree.

The Partial metering mode is a bit more picky, as it uses only the central region and completely disregards what’s happening around the edges of the scene. Spot metering is the most critical mode, as it uses only a very small point at the centre of the frame and everything else is disregarded – you therefore need to be very careful with your aim when you’re using this mode.

It’s also important to understand the difference that alternative autofocus modes can make to metering. In One Shot autofocus mode, metering will be locked at the moment that autofocus is achieved, for as long as you maintain a light press on the shutter button before finally fully pressing it to take your shot.

In AI Servo autofocus mode, which you’d use to track moving targets, the metering updates continuously as the focus setting adjusts itself. In AI Focus mode, metering remains fixed as long as the target remains stationery.

However, if the target moves and AI Focus switches to tracking mode, metering will be updated automatically.

You can lock the metering system to an initially captured exposure value, regardless of which autofocus mode you’re using, by pressing the AEL (Auto Exposure Lock) button on the back of the camera – it’s labelled with a star.

Overall, you can combine the various different autofocus and light metering modes to work in pretty much any way you want once you understand what each one does, making the most of the great versatility offered by current Canon DSLRs.

Step by step – Choose the right metering mode

1. Evaluative
This works well for general shooting, especially when you’re using multi-point autofocus, where a number of different autofocus points are likely to lock on to foreground areas with different brightness levels. Light and dark areas in the foreground will then be averaged out to produce a well-balanced exposure.

When photographers talk about ‘taking a reading’ or ‘metering a subject’, they’re usually talking about taking a Spot or Partial meter reading from a specific area in a scene and locking the exposure in. This guarantees that the subject you’re metering for will be exposed correctly.

However, you need to make sure that the area you’re taking a reading from is a midtone. If the area is dark in tone, and you don’t dial in ‘-’ exposure compensation to make it dark, this area will be set as the midtone, and the picture will be overexposed.

If the area is bright in tone, and you don’t dial in ‘+’ exposure compensation to make it bright, then this area will be set as the midtone, and the picture will be underexposed.

In our examples below we show you the effects of different metering modes and where within the frame you should take your reading.

1/100sec at f/22

Evaluative metering
Evaluative has done a good job here, although the highlights are slightly blown.

How Evaluative metering gets it wrong
Your Evaluative metering mode is reliable and accurate in the majority of day-to-day shooting situations. However, the exposure it comes up with is linked to the focus point (and AF points that have almost achieved focus), and this can cause problems if the subject in focus is very dark or very light in tone.

The solution, as always, is to check the histogram, and dial in exposure compensation if required (What is exposure compensation? See our cheat sheet).

1/500sec at f/22

Spot metering – highlight
Taking a reading from the white area makes the picture underexposed.

1/30sec at f/22

Spot metering – shadow
Taking a reading from the black area makes the picture overexposed.

1/125sec at f/22

Partial metering
Taking a reading from the grass (a midtone) creates a balanced shot.

Exposure and metering adjustments

Capturing the optimum exposure in-camera is critical if you want to get the best-quality results, and whichever metering option you choose there will often be some room for improvement. Your DSLR has a wide range of features that you can take advantage of to ensure you end up with the best-possible exposure, even in the most demanding of lighting conditions.

Exposure compensation
By rotating the Quick Control dial or pressing the ‘+/-’ button and turning the control dial (depending on the camera), you can apply compensation in 1/3 or 1/2 stop increments up to +/- 5EV. Reset to 0 when you’re done.

AE Lock
Your AE Lock function enables you to lock an exposure setting independently from the focus, then re-frame the shot. Dab the shutter release to activate the metering system, fill the frame with the subject you want to meter, then press the ‘*’ button and recompose the shot.

Exposure bracketing
The auto exposure bracketing (AEB) function enables you to take three consecutive shots: one as-metered, one slightly overexposed and one slightly underexposed. You can set the bracketing increments, and use AEB in conjunction with exposure compensation.

READ MORE

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Dial M for… Your exposure modes exposed

Choose a high-contrast subject

This picture of a lizard against a dark background is a good example, because there’s a big brightness difference. The camera doesn’t know which area needs to be correctly exposed – only you do! There are two solutions…

Set the AF point

The first option is to select the AF point that corresponds to the part of the picture you want to be exposed correctly. Remember that the AF point is where the spot reading will be taken from. Now take the shot again but with the AF point over a different area, like the background. The exposure will be very different! For more on this, check out our camera tips for how to choose the best AF mode.

Use AE-L/AF-L

Sometimes there won’t be an AF point in the right position for the area you want to take a spot reading from. Use the AE-L/AF-L button to lock the exposure (see our step-by-step guide on how to use AE lock to control exposure). Place the AF point over your subject, then reframe to shoot.

Compare with matrix metering

Do either of these attempts at spot metering give better or worse exposure results? Now shoot the same high-contrast scene using matrix metering and see how the exposures differ again.

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The brightness of the scene can vary enormously across the picture (learn When to use spot-metering). For instance, the sky will usually be much lighter than the foreground. As such, an average reading is needed for a scene like this.

Arriving at the perfect value isn’t made easier by the fact that the key area of your image will vary according to your composition and what you want to highlight (check out our 10 rules of photo composition – and why they work).

In our latest photography cheat sheet below we’ve highlighted the three main metering modes your camera offers and explain what each of them does.

Our illustrated infographic shows you where within the scene your camera takes its meter reading when using each different metering mode, and why.

Simply drag and drop this photography cheat sheet on to your desktop to save as a reference for the next time you’re stuck on which metering modes are best for your scene.

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The Metering Mode button on your camera is symbolised by an eye-shaped icon within a rectangle. Within your metering mode function you will have either three or four metering modes: spot metering (read our guide to when to use spot metering), partial metering, centre-weighted metering and evaluative metering.

As you will see in our latest photography cheat sheet below, each metering option measures the brightness of a scene in different ways, depending on what subject you are shooting.

Our infographic below breaks down each metering mode and explains how they work and when is best to use them. And at the end of this article we’ll show you how to switch the metering mode on your digital camera.

To see the larger version of this cheat sheet simply click on the infographic or drag and drop it to your desktop.

If you liked this, you might like some of our other cheat sheets, such as our guide to when to use small or wide apertures, or our guide to how to read a histogram.

How to change metering mode

Step 1
Press the Metering Mode button on your camera – symbolised by an eye-shaped icon in a rectangle.

Step 2
Use the Main Dial (or the right and left cursor keys at the back of the camera) to cycle through the options and  switch from one metering mode to the next. We used a Canon DSLR for the purposes of this exercise. It may be slightly different on your camera.

Step 3
On some models you will need to press the central Set button on the back of the camera in order to confirm the change you have made to the metering mode.

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To help you get started on your journey, here are the key things you should know about how to dial in the best camera settings for your DSLR.

Quality control

When it comes to file formats, shoot in RAW rather than JPEG. The extra data that’s captured by shooting in the uncompressed RAW format gives you more flexibility to improve your shots post-shoot.

Try to keep light sensitivity as low as possible – between ISO100 and 400. Most cameras produce digital noise at higher ISO ratings. Noise looks like grain in your images.

As for white balance, you can leave it on auto, but you’ll become more confident at knowing when certain lighting conditions require you to switch to a specific setting, such as Cloudy or Tungsten.

Key controls
Aperture and shutter speed are crucial. The combination of these two settings affects not only the amount of light you let into the lens, but also the way your images look.

The aperture controls the depth of field by determining which areas of an image appear sharp. If you want a shallow depth of field, with a sharp foreground but blurred background, you need to select a wide aperture (such as f/2.8), and vice versa.

The shutter speed controls whether a moving object is frozen or blurred in your shot. The slower the speed, the more motion blur you’ll create.

Setting the right exposure mode
DSLRs offer a range of exposure modes, from fully automated – like a compact camera – to fully manual. Two popular ‘semi auto’ modes are Aperture Priority and Shutter Priority, which give lots of creative control.

Aperture Priority enables you to dial-in your chosen aperture and the camera automatically works out what shutter speed is needed. If you know what shutter speed you want to use to create a certain effect, Shutter Priority lets you select it.

The camera then works out the aperture you need for a correct exposure. Simple!

Get metering right
Metering modes depend on the camera and the brand, but the three most common on a DSLR are Multi-zone, Centre-weighted Average and Spot.

Multi-zone mode takes a light reading from across 
a whole scene. It’s suitable for everyday use and pretty accurate in most situations. Centre-weighted Average takes a reading that concentrates on around 70% of the centre of the frame and feathers out towards the edges. It’s ideal for shooting portraits.

Spot metering reads a tiny area of the scene and is therefore the most advanced and precise mode.

Setting the AF and Drive modes
To make your shots pin-sharp, DSLRs offer a number of focus modes. The two main settings are single-servo, 
for stationary subjects, and continuous-servo, for moving subjects. Most DSLRs enable you to select a focus point manually, so that you can lock focus on off-centre subjects.

The Drive modes enable you to determine whether a single frame is captured each time you press the shutter release, if shots are taken continuously for as long as the shutter is pressed down, or if the shutter is fired automatically after a set delay.

Make the most of the rear LCD screen
Now you’ve got an SLR it’s time to ensure you are using the bigger, brighter LCD properly. By this we mean using the zoom buttons to zoom into parts of an image on the rear screen, so you can check for sharpness or excessive noise.

And you should also get into the habit of checking your image’s exposure by calling up the histogram, or tone chart. A histogram bunched up to the left indicates under-exposure; bunched up to the right it indicates over-exposure.

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Congratulations on getting a new camera! It’s only natural that you can’t wait to start using it, but it’s worth spending a few minutes configuring it correctly first. Not only will this save you time and effort in the long run, but it’s a good way of familiarising yourself with your camera’s layout, features and functions. With the help of our quick-start camera set-up guide, it will only take a few minutes…

Select high-quality pictures

When it comes to file format, shoot in raw rather than JPEG. The extra data that’s captured in the uncompressed raw format gives you more flexibility to adjust your shots post-shoot if necessary (see page 7 for more on the raw file format). Try to keep the ISO as low as possible, ideally between ISO100 and 400, because digital ‘noise’ can be a problem at high ISO settings. As for white balance, set it to auto for now – as you progress you’ll become more confident at knowing when to switch to a specific setting, such as Cloudy.

Choose the right exposure mode

SLRs offer a range of exposure modes, from fully automatic – like a point-and-shoot camera – to fully manual. In between these two extremes are the two popular ‘semi auto’ modes – aperture priority and shutter priority – which provide lots of creative control. In aperture priority mode, you set an aperture and the camera automatically works out what shutter speed you need for a correct exposure, while in shutter priority mode, you set the shutter speed and the camera works out the correct aperture. Simple!

Choose the right metering mode

Metering options depend on the camera, but the three most common are multi-zone (also known as evaluative or matrix), centre-weighted, and spot. Multi-zone mode takes a reading from the entire scene and then sets the exposure accordingly. It’s pretty accurate, and is suitable for most conditions. Centre-weighted mode takes a reading that concentrates on the central 60% of the frame, making it ideal for portraits, and spot mode takes a reading from a tiny area and is therefore potentially the most accurate.

Set the aperture and shutter speed

Aperture and shutter speed affect not just the amount of light you let into the lens, but also the way images look. The aperture is used to determine the depth of field, which is the amount of the scene that’s in focus. If you want a blurred background, you need a wide aperture, such as f/2.8; and if you want everything in focus from front to back, you need a narrow aperture, such as f/22. The shutter speed controls whether a moving subject is frozen or blurred; the slower the shutter speed, the more motion blur there will be.

Set the focus and drive modes

To ensure your shots are razor-sharp, SLRs offer a number of focus modes. The two main settings are single-shot, mainly for stationary subjects, and continuous or servo, for moving subjects. Most SLRs feature multiple focus points that can be selected manually. The drive modes enable you to select whether a single shot is captured each time you press the shutter release, whether a sequence of shots are taken in rapid succession, or whether the shutter is fired after a delay of two or ten seconds.

Take a test shot

Now you’ve set up your SLR, it’s time to ensure you’re using its LCD properly. By this we mean using the zoom buttons to zoom in on parts of the image on the rear screen, so you can check for sharpness or excessive noise. And you should also try to get into the habit of checking your image’s exposure by calling up the histogram, or tone chart. A histogram bunched up at the left can indicate under-exposure; a histogram at the right suggests over-exposure. If you’re unsure, adjust your settings and try taking another test shot.

Back to: Get to know your camera – introduction

Forward to: Explore your SLR

Getting your head around exposure can be daunting, so let’s start with the basics. When taking photographs, an image is recorded by light reaching your camera’s sensor. You need a certain amount of light to expose the scene correctly; too little and the image will be too dark, or under-exposed; too much and it will be too bright, or over-exposed. The amount of light reaching your sensor is controlled by three key components: aperture, shutter speed and ISO.

The aperture controls how much light is allowed through the lens – a wide aperture lets in more light, a narrow aperture less. The shutter speed determines the length of time the shutter remains open. Aperture and shutter speed work in unison to expose the image correctly, and if you adjust one you have to adjust the other: if, for example, you increase the shutter speed (therefore decreasing the length of time that light hits the sensor), then you have to use a wider aperture to let in the same amount of light to expose the shot correctly.

The other variable that affects exposure is ISO. The ISO setting affects the sensor’s sensitivity to light. The lower the ISO, the more light is required to expose the image.

Understanding exposure

To determine the aperture and shutter speed required to expose a shot correctly at a given ISO, your camera measures the amount of light reflected back from the scene using a built-in light meter. The key word here is ‘reflected’. Camera meters assume that the scene you want to photograph contains a full range of tones, and tries to expose it accordingly. This means that certain lighting conditions can confuse them – dark scenes can be over-exposed and bright scenes under-exposed – because the meter will try to expose the light or dark areas as midtones.

Dark scenes

A built-in light meter will try to produce an exposure made up of average midtones. A dark scene that’s been exposed so it’s dominated by midtones will therefore look over-exposed.

Mid-tone scenes

Scenes containing a relatively even mix of shadows, midtones and highlights, such as in the photo above, won’t give your camera’s metering system too many problems.

Bright scenes

As with dark scenes, because the built-in light meter will try to render any scene as an average midtone, very bright subjects like snow will end up looking a bit grey, rather than pure white.

How to read a histogram

You can call up the histogram on your camera’s LCD to judge the tonal distribution in a photo. The horizontal axis shows pixel brightness, ranging from pure black on the left to pure white on the right. The vertical axis shows the number of pixels at a particular brightness level.

Under-exposed

Not enough light has reached the sensor, caused by either too fast a shutter speed, too narrow an aperture, or both. This shot’s histogram is pushed all the way to the left, a situation known as ‘clipping’. If printed, the clipped areas will appear completely black, and all shadow detail will be lost.

Correctly exposed

The histogram should correspond with the tones of your scene; a dark scene should have a histogram with a bell shape on the left; a light scene should have a histogram with a bell shape on the right. For daylight scenes, expose the scene as far to the right as possible without clipping the highlights.

Over-exposed

Too much light has reached the sensor. Notice how the histogram reveals that the tonal distribution is pushed all the way to the right, and that the highlights are clipped. In the printed photo, areas of the scene that should reveal detail will appear as pure white, with no detail.

Metering modes

Multi-zone metering

This is also known as matrix, evaluative, multi-segment and pattern metering, depending on the camera you have, but all serve the same purpose. Multi-zone metering is generally the default setting on your camera when you first switch it on. In this mode, the camera divides the scene into sections and takes a reading from each section to determine an overall reading for the whole scene.

Centre-weighted metering

Centre-weighted metering also takes a reading from the whole scene, but concentrates mainly on the central 60% of the frame. It’s handy for portraits, especially when the model is in the centre of the frame. Centre-weighted metering can easily be fooled by very bright or very dark areas, but it can be easier to predict when you need to adjust the exposure than it is with the multi-zone metering mode.

Spot metering

This is the most accurate metering mode because it enables you to take a reading from a small, precise area of a scene. However, it can take a bit of practice to be able to judge precisely what constitutes a suitable midtone. To simplify matters, some photographers meter off a so-called ‘grey card’ placed in the same light source as the subject. You can pick one of these up from Jessops for around £6.

Back to: Explore your SLR

Forward to: Understanding aperture