Your Quick checklist for sharper shots
Soft shots are the bane of the photographer's life, so it's important you do everything you can to keep your images sharp. Here are some tips to help you...
1) Is your subject still?
If so, try using Single AF mode, and placing the AF point over an area which needs to be critically sharp, such as the eyes in a portrait. You could also change to manual focus, but this leaves more to chance if you are not that familiar with it. When shooting a still life, manual focus makes sense as you can ensure the whole area is sharp. Consider mounting your camera on a tripod too, as the still life composition is not going anywhere. The same goes for plants and flowers.
2) Is your subject moving?
When subjects are moving, for example a running dog or a playing child, change to continuous AF mode, also known as AI Servo on Canon cameras. Here, the camera will track the subject, but you can't just rely on this. You will also need to set single point focus over the eyes. You can turn on multiple AF points, but your camera might get confused and focus on the wrong thing. For subjects that move quickly and erratically, such as a football player or a bird in flight, you can also prefocus on an area that the subject will move into.
3) Make sure your shutter speed is fast enough
There's an old rule from film photography that says the shutter speed needs to be at least one second divided by the focal length of the lens. Shooting with a 50mm lens will therefore require at least 1/50 second shutter speed, in other words, but it's best to aim a bit higher, depending on the subject. If you have a high resolution SLR, such as the Nikon D810, any slight camera shake will be painfully obvious in the high resolution files, so try not to let the shutter speed drop below 1/125 second when shooting a dynamic event outside, such as wedding, or when doing travel or street photography. You have more leeway if your camera is tripod mounted, or your lens is image stabilised. Image stabilisation can give a leeway of up to four stops.
4) Make sure the ISO is set correctly
Higher ISOs not only increase your camera's sensitivity to light, thereby enabling you to get more shots in poorer light conditions, they can also increase the available shutter speed. So there are times you might need to go behind ISO 1600 or beyond, especially when shooting at a wider aperture in less than perfect light. Don't fret unduly about this: while you might have to go into your image editing software to reduce noise, better a slightly noisy shot than a soft one. Depending on how big you print, the viewer might not even notice noise in the first place – not everyone is going to be viewing your image at 100% on a computer screen!
5) Ask yourself if you need a tripod
It can be tempting to try and shoot handheld all the time, especially if you are lucky enough to have an image stabilised lens, but this can lull you into a false sense of security. While they can be a pain to carry around, tripods will usually guarantee stability and sharper shots, and they also force you to slow down and be more mindful about composition and framing. There are times when a tripod is absolutely essential. If you want to shoot traffic trails from cars at night, for example, you will need a long exposure, anything from 10-30 seconds. However firmly you hold your camera or brace yourself, you will never be able to compete with the level of stability offered by a tripod.
6) Are you thinking about the effects of aperture?
The aperture setting – how much light is allowed to fall onto the camera sensor via the lens – also has a big effect on sharpness. When taking portraits, the temptation is to use a very wide aperture, eg f/2.8 or wider. While the restricted depth of field you get will mean that you can blur the background out nicely, the areas that need to be sharp (eg the eyes in a portrait) will have to be absolutely pin sharp, as all the viewer's attention will be on them. So by all means enjoy the benefits of wide apertures, but set the AF point very carefully on the areas that need to be critically sharp, as discussed. At the other extreme, if you select a narrow aperture (eg f/20) you will get more depth of field in your landscapes, but your camera will need to use slower shutter speeds to ensure that enough light gets through to expose the shot. So again, make sure you use a tripod....