Take Control of the AF Point
Don’t leave it up to the camera to decide where to focus. It won’t know which feature you want to be sharp in the picture, and if there’s something in front of the main subject, or the background is detailed, or there’s not a great deal of contrast between the main subject and the rest of the picture, then your camera may focus on these and not the subject.
You’ll get more consistent results if you tell your camera which part of the frame you want to focus on. For absolute precision, choose a single AF point. The centre spot is the most sensitive, although not best-placed for the most dynamic compositions.
For an off-centre subject, you’ll need to use the ‘focus and recompose’ method: point the central AF point on the subject, half-press the shutter release to lock the focus, and then recompose the shot. Alternatively, use an off-centre AF point that corresponds with the positioning of the subject in the frame. This is the best option if you are taking pictures at close quarters; if you opt for the focus-and-recompose method instead, the shift in camera position can mean that the point you locked focus on is now at a different distance relative to the position of the sensor, and may actually be blurred.
Keep an eye on the Shutter Speed
The rule of thumb for handholding is to set a shutter speed equivalent to (or faster than) one divided by the focal length you’re shooting at, so that’s 1/50 sec when shooting at 50mm, 1/400 sec at 400mm and so on.
But your hit rate may vary when it comes to keeping a lens still at these shutter speeds. Vibration Reduction (VR) lenses make a difference at slower speeds, but will have no effect on any subject movement.
If in doubt, use a shutter speed that’s twice as fast – you may need to increase the ISO, but better to have a sharp, grainy shot than a blurred one.
If your subject is moving, you might have to go even faster – even if you’re able to eliminate camera shake, if the shutter speed isn’t fast enough to ‘freeze’ the movement, your subject will end up looking blurred.
A tripod is the best way to ensure sharp photos at very slow shutter speeds, but even the sturdiest set of legs may not prevent details from looking smudged if the camera isn’t perfectly stable.
The action of pressing down on the shutter release button can jog the camera, so it’s worth triggering the shutter with a remote release, or using the self-timer or exposure-delay function for pictures that aren’t time-sensitive.
Vibrations caused by the mirror moving (to expose the sensor to light) can also lead to soft shots. To remedy this, use the camera’s mirror lock mode or activate Live View, as the mirror is moved out of the way in Live View.
Use the Optimum Aperture
Although there will be situations when you want to use a large aperture to help you separate a sharp subject from a blurred background, there will be other times when you want more of a scene to appear sharply focused. It might be tempting to reach for the smallest aperture on the lens, but this actually leads to softer pictures due to the effects of diffraction – essentially incoming light rays being bent out of shape by the aperture blades, which is more noticeable at small apertures.
It is often preferable to sacrifice some depth of field in order to deliver an image where details are pin-sharp. This is often in the middle of a lens’s aperture range – typically around f/8 to f/11, although this varies from lens to lens.
Do Not Zoom after you Focus
Most of the zoom lenses made today aren’t in fact true zooms, or what are known as ‘parfocal’ lenses; rather, they’re ‘varifocal’ lenses. One of the drawbacks of this type of design is that the focus shifts as the lens is zoomed. This means that if you zoom in to lock the focus on a detail within a scene and then zoom back out to take a shot, there’s a good chance that the detail you want to appear sharp will now be blurred. If the zoom range isn’t too great, the change in focus may be subtle.
Using a small aperture to give a large depth of field – the amount of front-to-back sharpness in a picture – can also mask any focus shift. But the easiest way to prevent this is to get into the habit of only focusing after you’ve zoomed. Once it becomes part of your shooting regime you won’t even have to think about it.
Make the most out of Manual Focus
When you use autofocus, there are a number of links in the chain that can break, leaving you with soft pictures. For instance, a lens may suffer from a back-focus or front-focus issue, where the sharpest focus is actually fractionally behind or in front of the edge that your AF point has locked onto.
For this reason, for critical work where focus is everything, such as macro photography or landscapes, manual is the way to go. Live View potentially makes this a piece of cake, allowing you to magnify details to 100 per cent. However, some cameras use so-called ‘interpolation’ to create the magnified view, resulting in a Live View image that’s not particularly sharp, and therefore harder to judge. One option here is not to magnify the image too far.
Alternatively, shoot in RAW and then fine-tune the Picture Control setting to produce a sharper, higher-contrast preview image that’s easier to judge focus on – shooting in RAW rather than JPEG means the image will be unaffected by the effects of the Picture Control setting.
Use the correct AF mode
Many DSLRs have three autofocus modes: one for stationary subjects, one for moving subjects, and a mode that automatically switches between the two, depending on whether the camera detects movement and decides that your subject is mobile.
However, cameras don’t always get it right, so for absolute peace of mind, always set the correct mode manually.
Check out Exposure Compensation
Matrix or Evaluative Metering does a fine job of producing balanced exposures for the majority of day-to-day photo opportunities. However, faced with an overly bright or dark subject or scene, the camera can get things wrong.
Despite Matrix metering essentially applying its own exposure compensation to deliver what it determines is an optimum exposure, it may not be accurate. Manually dialling in exposure compensation at the time of shooting is far better than trying to rescue an under- or over-exposed image later.
Pushing the brightness of an image that’s very dark in Photoshop can lead to noise in shadows, while trying to eke some detail from burned-out highlights can lead to ‘digital’-looking results.