Digital cameras can do a lot, but they don’t always get it right – sometimes you have to take a bit more control over the exposure, but without resorting to a fully manual exposure.
There are some classic situations that “fool” cameras – snow, a bright spot of light in the scene, intermittent lights and so on. If you find that no matter how many times you press the shutter button the shot is either too dark or too bright, then one of the tools at your disposal to overcome this is Exposure Compensation. (Note – you may want to also look at the metering mode you’re using – that can often help too.)
Let’s say, for example, that your shot is too dark, like the cheetah above – you need to tell the camera that you want a slightly brighter exposure. Using the exposure compensation function, you can set the camera to effectively overexpose, i.e. make the shot a bit lighter by a partial stop, a full stop of even multiple stops – how much depends on what you need and on what your camera will allow. Most cameras, especially DSLRs, will offer 1/3 stop increments, often up to 3 whole stops or beyond.
To dial in your exposure compensation value, first you need to half depress the shutter button whilst composing your shot. This gives the camera a base exposure value that it thinks is correct. Then, using either a dedicated button, one of the wheels on the back of the camera or the menus (sorry, but every camera is different – check out your manual for Exposure Compensation or look for the +/- symbol on your camera), dial in a compensation value. You should see some kind of indication on the camera of how much compensation you’re dialling in. To make a bright image darker, you need to move toward the negative end of the scale – conversely to make a dark image brighter, as below, move towards the positive end of the scale.
Initially the amount of compensation you apply will be a bit of trial and error, but in time you’ll become more instinctive as to how much you need.