There are fewer more frustrating problems in photography than getting back from a shoot and discovering your shots aren’t sharp. Blurred images can rarely be fixed by sharpening in post-processing software, and more often than not the pictures end up in the trash can.
Whether the frame is soft, fuzzy or with an unexpected focus, there’s always a reason the detail isn’t well-defined, but there’s also a simple solution to fix it. Take a look through these five explanations a photo might suffer from a lack of sharpness, and banish unwanted blur for good!
1) Camera shake
This is a problem that every photographer encounters at some stage, and is incredibly easy to remedy. Camera shake occurs when your camera moves during the exposure – especially when slower shutter speeds are used – and results in all detail in your shot looking soft. It’s easily identified by the telltale smudging of detail, any specular highlights are streaks rather than spots of light and subject detail has a ghosted double edge.
Camera shake happens when your camera moves during the exposure
This can be fixed by either used a faster shutter speed, keeping your camera perfectly still or by using a lens or camera that has built-in Image Stabilisation (also sometimes called Vibration Reduction). There’s a rule of thumb for your shutter speed and avoiding camera shake: your shutter speed value you should be equal to or higher than the number of your focal length. If you were shooting with a 50mm focal length, then your shutter speed should be 1/50 sec or faster. This rule applies to full frame cameras. If you’re using an APS-C camera then these have a crop factor of 1. 5x, meaning a 50mm focal length is actually 75mm, so your shutter speed needs to be 1/80sec or faster. To be more confident of ruling out camera shake when shooting handheld, use a lens or camera that offers Image Stabilisation. They’re designed to counteract any detected motion and allow you to shoot from 3 to 5-stops slower than would ordinarily be possible without encountering shake.
Alternatively, fix your camera to a tripod and use a shutter release cable to take your shots. This way you can be assured your camera is perfectly still during the exposure and you won't be at risk of shake. This method is essential if you’re shooting slower exposures, either because there’s not enough light or you require a slow shutter speed to capture motion blur.
Using a tripod will keep your camera steady and avoid shake
2) Focusing error
Focusing incorrectly will write off your shot before you’ve even pressed the shutter button. We’ve all done it at some point, and you can tell a mistake has been made with the focusing as the key subject is soft while the background of the shot is razor sharp. It’s really easy to fix, and the first thing to check is that your camera or lens is set to use Autofocus. You want the switch on the lens and the body to be in the AF position. Sometimes a gentle knock can cause them to be set to Manual focus (M/MF) and the camera won’t automatically set the focus. With Autofocus enabled, just make sure your active AF point is resting over the area of the image you want to be sharpest, and then half press the shutter button to set the focus. Most cameras emit a beep when the focus is set, and you can turn this on or off within your camera’s menu. Once you hear the beep, fully press the shutter to take the shot. Zoom into the image on the LCD to check the focus has been set accurately.
A common focusing error is discovering the background is sharp and the subject soft
3) Subject movement
There’s one simple fix to avoid the blur caused by subject movement, and that’s to use a faster shutter speed. You can easily tell when subject movement is the cause of the blur, as the only soft detail in the shot is the moving subject itself - everything else should be solid and sharp. Of course the shutter speed required depends on the speed of the moving subject. A dawdling pedestrian could be captured sharply with a speed of 1/125sec, but a galloping racehorse would need a much faster exposure time, like 1/1000sec. If you’re unsure take a test shot and zoom into the image on your camera’s LCD and check moving detail is sharp. If it isn’t, simply increase your shutter speed and check again to make sure it’s satisfyingly sharp. If there’s not much light, you’ll need to increase your ISO to make your camera more sensitive to light to still capture a balanced exposure.
To avoid the blur of subject movement increase your shutter speed
4) High ISO and Noise Reduction
Sometimes you might boost your ISO when the light level drops, and by increasing your camera’s sensitivity you’ll introduce digital noise (grain) into your images. This is to do with the ‘Signal-to-Noise’ ratio (SNR), and all electronic devices that receive a signal suffer the same effects in one way or another. It’s a bit like when you crank up the volume on your speakers, you can hear more of a background hiss. You can easily identify if Noise is the cause of your image softness as there’ll be a noticeable grain in your shot, especially prevalent in the shadows.
A high ISO setting creates lots of grain in your image, resulting in softer detail
Another consequence of high ISO settings and grain is Noise Reduction, and this is your camera’s attempt to suppress the grain in your shot. By reducing the appearance of grain, it leaves images with a more ‘waxy’ finish, and fine detail is smoothed out. You can avoid this problem by keeping your ISO low whenever possible, or if you need to shoot with a high sensitivity then it’s best to shoot RAW rather than JPEG, and apply your own Noise Reduction in post-processing software. This way you can finely control the amount of Noise Reduction to get the perfect balance between grain and sharpness in your shot.
Shoot in RAW and precisely control how much Noise Reduction is applied to your pics
5) A fault with your lens or camera
If you notice your images aren’t sharp where you’d expect them to be, and you’ve already ruled out camera shake, focusing errors, subject movement and high ISO settings, then it’s likely there’s a fault with your camera or lens. Sometimes dropping a lens can cause the glass elements inside to become misaligned and the image will become soft. Try your lens on another camera body and if you’re getting the same unsatisfactory results the problem is with the lens. You’ll need to return your lens to the manufacturer or a specialist repair centre to get the problem fixed. If your lens operates as expected on another camera, and other lenses are equally soft on your camera then the problem is with the camera itself. This could be down to a number of issues, and again you’ll need to package up your camera and send it off to the manufacturer or repair centre for analysis.
A fault with your camera or lens results in an unusual focus: note how the wine glass is sharp, the subject's face is blurred yet the background of the shot is sharp too.
. digitalrev.com2017-10-12 03:00
