I'm sure like me you've taken a photo and then later when viewing it on a bigger screen, realised that it's not sharp. There are two main physical reasons why this might be the case:
The image is blurred across the scene as there has been camera movement whilst the shutter was open
The image is blurred across key parts of the scene because of how and where you focussed. It's not possible for everything from very near to very far to be in focus, and so it's important to make sure that the most important parts of the image are in focus.
In this article we are going to explore the main reasons for blur, both from camera motion and from focussing, so that you can ensure sharp images every time.
1 Use a tripod
Whenever you're using longer shutter speeds, a tripod is a must, and longer shutter speeds are inevitable when light levels are low. So, unless you always shoot on bright sunny days, a tripod is essential. A rule of thumb is that whenever your shutter speed drops below 1/50th of a second, you must use a tripod to prevent camera movement while the shutter is open (and potentially blurred photos). Any tripod will do, but whichever one you use, make sure everything is done up tightly before you take the shot.
Pro tip: A better rule of thumb for the point at which a tripod is necessary is 1 divided by your focal length. E.g. if you are using a wide angle lens at 14mm, you can get away with hand holding the camera for shutter speeds as slow as 1/14th of a second and still get sharp images. However, if you are using a zoom lens at 200mm focal length, you will need to be on a tripod for any shutter speed slower than 1/200th of a second! As cameras and lenses often have image stabilisation, you can often get away with slower shutter speeds than this, but it's still a useful rule of thumb, and ensures you err on the side of caution.
2 Use your two second timer
If you're using longer shutter speeds and have your camera on a tripod, that's not the end of the considerations to ensure sharp photos. As the shutter speeds get slower, any tiny movement of the camera can cause movement blur and ruin the sharpness of your photos, and that includes you pressing the shutter! An easy way to avoid camera movement is to use your cameras two second timer; this means you can press the shutter, and the camera pauses for two seconds before opening the shutter, avoiding any camera shake caused by you touching the camera. If you don't have a two second timer, then any remote release (cable, infra red or bluetooth) will do the job just as well.
3 If it's windy, add some weight to your tripod
Using a tripod in windy conditions has a new set of challenges, as the wind can rattle the camera and tripod enough to ruin the sharpness of your photos (even if you can't see it moving). You can help to prevent some of this movement by wedging one or more of your tripod legs up against a solid object if there is one nearby (e.g; a wall, fence or rock). If not, and you have a camera bag with you, you can use the hook (which most tripods have underneath them) to hang your bag in order to add more weight and therefore make your tripod more stable. If possible, try and arrange it such that your bag hangs from the hook, but also touches the ground slightly, otherwise in windy conditions, the bag can actually act as a sail and wobble your tripod even more!
4 Use a smaller aperture
Your choice of aperture will influence how much, and where the image is in focus and therefore sharp. All apertures have a 'plane of focus' (also known as 'depth of field'); this is the area in front, and behind the point that you have focussed on, that is in focus. Areas outside of this plane of focus will be increasingly blurred as you go further towards the camera, and further towards the distant horizon. Smaller apertures (denoted by larger 'f' numbers, such as f16) have wider planes of focus. Larger apertures (denoted by smaller f numbers such as f2.8) have narrower planes of focus. So, if you are taking a landscape photo, choose a smaller aperture such as f11 or f13 (using aperture priority or manual modes) in order to ensure that as much of the scene as possible is sharp and in focus.
5 Focus one third into the scene
Just to complicate matters, the depth of the plane of focus (the amount in front and behind where you focus that is properly in focus) also depends on WHERE you focus, not just which aperture you have selected. This means that if you choose an aperture of f11, but you focus on a flower very close to you, you will be narrowing the plane of focus and you're likely to find that the view behind the flower is out of focus and therefore blurred. In order to make your plane of focus as wide as possible, a rule of thumb for landscapes is that you should focus 1/3 into the frame. So, imagine that you were standing on a clifftop with some flowers in front of you, a beach below and some hills in the distance. To maximise your plane of focus, focus on a point that is around 1/3 into the frame; in this instance this is probably somewhere on the beach below. This will ensure that as much of the scene as possible is in focus; however, because of the laws of physics, you are likely to find that the flowers in front of you are slightly soft focus, as are the hills in the distance.
Pro tip: If you decide that the flowers are the main subject of the photo are the flowers in front of you, then you can of course decide to focus on these in order to make sure they are in focus and sharp. Because focussing close to you will reduce the depth of the plane of focus, the beach below and the distant horizon will be in soft focus, but this is the creative choice that you have made for this scene.
6 Make sure your viewfinder is in focus!
If you use the viewfinder to compose photos rather than the back screen of your camera, then it's important to know about something called the 'dioptre control'. This is a little wheel, usually just to one side of the viewfinder, which adjusts the focus of the viewfinder to match your eyesight. So, simply look through the viewfinder and turn the wheel until the view is in focus. If you don't do this then it's going to make using the viewfinder to compose photos and ensure they are sharp, very difficult!
7 Buy the best lenses you can afford
Image sharpness varies between lenses, and as with most things in life, you get what you pay for! When spending money on kit, I always advise students to spend as much as they can on lenses, since the best lenses can last a lifetime and will have the best image characteristics such as image sharpness. Given the choice of spending money on the latest upgraded camera body, or upgrading to the best lenses, I would always say the latter!
Want to learn how to take photos like a pro?
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