The exact distance setting used to photograph an object is known as focusing. The object should be focused by adjusting the camera as well as the lens.
Often, people don’t really pay attention to using the right focus when photographing, but by keeping the amount of focus in mind when taking pictures, you can widen your creative possibilities exponentially without having to master too much technical know-how.
An image appears especially sharp when the contrast between surfaces and contours is as large as possible. Absolute statements can’t be made about focusing, however, and most people tend to see the sharpest photos as those that reflect reality as closely as possible.
Pixels in the focal plane are displayed as dots on the photo sensor of the camera. When the camera isn’t correctly focused, the dots turn into circles. When neighbouring circles overlap on the sensor, this makes the image appear blurry. However, when this overlapping is smaller than the human eye can see, the photo will still appear to be sharp. In a photo with the dimensions 10 x 15 cm, for instance, the viewer will only begin to notice blurriness when the diameter of the circles is 0.1 mm. Besides camera shake, incorrect focusing is the second most common reason for an image turning out blurry.
Another important thing to consider when focusing your camera is what exactly you should be focusing on. When photographing humans and animals, you should focus on the eyes. When the subject is slightly facing away from you, it’s best to focus in on the eye that is closest to the camera. This will reflect reality as closely as possible and thus appear sharper.
The same basic concepts apply when photographing objects. When this is the case, the area closest to the camera should be focused. There are also differences to consider: in macro photography, the area closest to the camera is often too close for the lens to correctly capture. When this is the case, the photographer should focus on an area further back. This results in a blurred fore- and background, but a focused centre.
The adjustment of the focus can be done using either autofocus (AF) or manual focus (MF).