All relatively modern cameras have an autofocus function. However, this does not mean that you can literally point and shoot and expect the focus to be correct.
Decide on the point of interest and then focus on it!
You need to decide exactly what element of your subject should be in focus and in order to ensure that this happens, it is necessary for you to understand how the focussing system works.
In the picture of this lion, if you had simply framed the picture as you see it here, the nose would have been in focus and the most important element, the eye, would not.
Autofocus is automatic on all compact cameras (point and shoot). An SLR (single lens reflex) camera allows you to change lenses and to change the mode from autofocus to manual. For the purposes of this lesson, we will assume that you are using a compact camera set to Program mode.
Focal plane is simply the area inside a camera onto which light is focused. In a film camera the film rests on the focal plane and in a digital camera the sensor (the thing that records the picture!) rests on the focal plane. The lens focuses the light onto the focal plane and it stands to reason that the light will fall onto the sensor at 90 degrees. It follows that if a subject is at right angle to the lens, then focussing on the subject will ensure that the entire subject is in focus.
If the subject is at an angle to the lens, then you will only be able to focus on one point.
Because this page is not at right angles to the axis of the lens (put another way – not parallel to the focal plane) only a small area on the page is in focus.
The most important part of the image is seldom in the centre of the picture.
Although composition will be the subject of a later article, it is important to know that most cameras allow you to focus on the main feature of the subject by holding the shutter halfway down and then, keeping the shutter in that position, you can move the camera to re-compose the picture before releasing the shutter.
A good principle to follow is that you focus on the major feature of the nearest object. However, this is a general rule which only applies if there are a number of points of interest, all of which should be as sharp as possible. In the lion picture above, it is essential that the eye is perfectly sharp at the expense of the nose, which is closer to the camera.
Focus on the nearest point of interest.
The girl is far more beautiful than the guy in sunglasses! Focus on her nearest eye, then re-compose and shoot. Point the centre of the viewfinder to the girl’s left eye, hold the shutter halfway down, allow the camera to focus and then, holding the shutter in the same position, re-compose and shoot – her face would have been in focus and his would have been OK but not perfect – a much improved picture would have resulted.
Focus, re-compose, shoot.
Both babies are in focus because the centre of the view finder was lined up with the nearest eye – the baby on the left.
The closer you are to the subject, the smaller the Depth of Field. The Depth of Field is the area of the picture that is in focus (more on this in a later article). In a landscape picture, provided you are not too close to the foreground, most of the scene will be in focus. However, if you’re shooting a close-up portrait, the nose may be in focus and the eyes not. It is very important to ensure that you focus on the right feature of the image. No-one wants to look at a nose – focus on the eyes and if the face is at an angle, focus on the nearest eye.
In this landscape of a Karoo onion farm, the entire scene is in focus – in other words it has a large Depth of Field because the subject matter is not close to the camera. Most compacts have settings such as Landscape, Portrait, Action, etc. Be sure to use this feature because the camera will be set up automatically to take the best shot possible of the subject that you wish to shoot.
To summarize
- Autofocus does not mean that everything will automatically be in focus
- Focus on the main feature, re-compose and then shoot
- Focus on the nearest feature to achieve optimum results
- If there is only one main feature, focus on that and then re-compose
- The closer the subject, the more critical the need to focus correctly
- Use your camera’s scene functions
In Mini-lesson 3 we will tackle composition – in this lesson you will learn the basic techniques of good composition. In Mini-lesson 1 we emphasized the need to always be on the lookout for good photo opportunities. After Mini-lesson 3 you will really begin to understand how to recognize an opportunity and then how to compose the picture in the best possible way.
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