Shooting Modes; Automatic, Semi-Automatic and Manual
The range of modes and settings can seem daunting at first. The best – and quickest – way to become a confident photographer is to experiment with your camera on every setting, so you fully understand how ISO, aperture and shutter speed inter-link. It’s often better to do this exercise without having another person involved – having to worry about your subject getting bored or uncomfortable adds unnecessary pressure at this stage!
In summary, the different exposure modes are:
In this mode, you only set the ISO – the camera chooses the aperture and shutter speeds according to the amount of reflected light it meters from the scene, as it attempts to render that scene so that mid-tones are exposed correctly. This mode is the quickest and easiest to get started shooting with, but leaves all the exposure decisions down to the camera. Even the most expensive camera has no idea what your intentions are, so you risk limiting yourself to decidedly average images if you never venture away from Programme Mode – consider using it at all a bad habit!
Aperture Priority Mode
This is the mode to use when depth of field is the most important consideration. If you want a blurred background to your portrait, choose an ISO setting most appropriate for the available lighting and dial in a wide aperture. The camera decides which shutter speed will result in a mid-tone being correctly exposed, according to its internal algorithms. Again, the camera doesn’t know what kind of portrait you are trying to create, so in any scene which has high contrast, backlighting or extremes of light and dark, the final result may not be what you were hoping for.
Shutter Priority Mode
This mode will help you control how motion is recorded, whether you want to freeze it or include it as a blur. Choose an ISO then dial in how long you want the shutter to remain open for, bearing in mind the risk of camera shake if the shutter speed’s denominator is less than the length of the focal length (e.g. on a 50mm focal length, keep the shutter speed above 1/50th of a second). The camera will select an aperture that will result in a mid-tone being exposed correctly.
Exposure Compensation adjustments
When using any of the above semi-automatic modes, you can use exposure compensation to quickly increase or decrease the exposure. Hold down the button marked with the +/- symbols in a box and rotate the dial – if the scene is overexposed dial in around -0.5 to -1.5EV depending on how big an adjustment is required; if it’s underexposed, dial in around +0.5 to +1.5EV, again depending on how much exposure needs adding. This provides a quick fix to your images while you build your confidence to shoot in Manual Mode.
Only in manual mode are you fully in control of each exposure. You’ll need to select the ISO, aperture and shutter speed most appropriate to the image you are trying to achieve.
Some DSLRs have exposure indicator scales displayed inside the viewfinder, to give a guide of how bright or dark the exposure will be using the current settings. You can use this to make quick adjustments to your shot, or review the image on the preview screen after you’ve taken it, tweak and try again.
With time, you will start to be able to roughly guess which settings will work in different situations. Once you’ve nailed the exposure, you can focus on the composition and interaction with your subject. You only need to adjust the exposure settings again if the light changes or if you want to vary the outcome.
Even when you are using manual mode, some settings can still be automated, such as the focus and white balance settings, although these too can be switched to manual control separately.
Balancing the exposure triangle
Each of the three settings you adjust in manual mode affect the brightness of the final exposure, and also have positive and negative side effects that need consideration – the image degradation of using high ISOs, the shallow depth of field of wide apertures and the risk of camera shake and subject blur with a slow shutter speed, for example.
Your settings should be determined by the final image you have in mind, including any steps you want to take in post-production. Baby photographers often overexpose slightly, to help smooth out the baby’s skin. For a moody portrait, you may want to underexpose for added atmosphere.
On a real life shoot, you often need to change and adapt according to how the light changes. For example, if you are a photographing a couple outdoors, you may want a wide aperture so that the background behind them is blurred. So dial in f/2.8. If it’s bright, you might start with an ISO of 100 and a shutter speed of 1/1000th of a second. After a few shots you may ask the couple to move under some trees. The light levels are slightly lower here, so you could either increase the ISO or decrease the shutter speed – either one will result in a brighter exposure.
Neutral density filters
On a very bright day, you may have your camera on its maximum shutter speed and its minimum ISO, but find there’s still too much light to use your widest aperture, as the image is overexposed. Or you want to use fill in flash to brighten some shadows caused by the sun behind your subject, yet the fastest shutter speed at which your camera can sync with the flash is 1/250th of a second, which means the image will be overexposed if you use a wide aperture. In both of these situations, adding a neutral density filter to the front of your lens will fix the problem. These tinted glass discs screw securely into the end of the lens, reducing the amount of light that can enter. They come in varying tints, affecting how much they reduce the exposure by.