When working in automatic mode on your DSLR, your camera will make the decision for you regarding what it thinks the correct exposure settings need to be by using its internal light meter.
So, what exactly is light metering?
Light metering is how your camera decides what your exposure settings should be based on the amount of light that is hitting your image sensor. Contrary to earlier days of photography when our devices were not equipped with a light meter – photographers now no longer need to rely on a hand held meter to determine the optimal settings.
Not to worry, even when working in manual mode your camera is still going to help you choose your best settings. You can view your DSLR’s meter in action by taking a peek inside your viewfinder. You will notice a series of bars or dashed lines toggling from left to right with a zero marker indicating your center – or in this case optimal exposure. Your meter will also most likely be displayed on your digital info screen on the back of your camera.
The easiest way to get used to this tool is to practice aiming your camera at various light sources to observe your light meter shift from side to side. When aimed at a brightly lit area – you will see the lines shift to the right (positive) side – indicating your current settings will allow too much light to enter. This results in an overexposed photo.
Likewise, pointing your camera towards a scene with lower light will cause your indicator to shift towards the negative end – prompting you to adjust your settings to let more light in.
As additional practice, I encourage you to keep an eye on your meter while you adjust one setting at a time. Seeing this scale working will give you first hand insight as to how each setting affects your exposure individually.
First, watch your indicator shift to the positive end as you take a small aperture of f/7.1 to a much larger aperture of f/2.2. Next, repeat the process with your shutter speed. A low shutter speed of 1/125 will have much more time to let in light than a high shutter speed of 1/2000. Watch your meter shift as you switch between the two settings.
Note: If you are having troubles making your meter move, make sure your cameras exposure mechanism is initiated when pointed at your subject. You can do this either by pressing your shutter release button half way down or pressing your back button if “back button focus” is your method of choice.
Once you have a handle on your camera settings and your personal preference stylistically – your internal light meter is going to be your best friend. For instance, I prefer to slightly over expose my indoor lifestyle photography so I make sure to adjust my settings until my meter indicates one stop above my zero marker. For outdoor photos, especially when shooting in to the light, I tend to expose for one or two stops below zero as to avoid blowing out the highlights in the sky. Each of these methods are purely my stylistic choice and every photographer is free to develop their own personal preferences.
Learning how to read your meter and having an understanding about how each setting will directly affect it will make vast improvements on your photos straight out of camera. This process takes the guessing game out of shooting and puts all of the control in your hands. In Part 2 of this series, I’ll discuss how you can take this technique one step further by metering for specific parts of your frame and using separate your cameras’ metering modes.