Depth of field
How to produce a greater effect of depth
Depth of field and creative play with the foreground and background is an essential creative technique in photography. We will show you what factors influence depth of field and/or depth of sharpness and how you can use these.
Colloquially, the term 'depth of sharpness' has become more common than 'depth of field', but linguistically they have the same meaning. In technical literature, the term 'depth of field' - standardised in 1970 - is mostly used. This defines the focus range in which an object is sharply in focus in the camera's optical system. On the picture above it is very easy to see that only a small area, namely the flower of the poppy, is really sharp, whereas both the foreground and background are indistinct.
For detailed and portrait shots, depth of field is primarily used as a means of concentrating the viewer's attention on the main motif, instead of distracting him with too many details in the background. With landscape shots, on the other hand, as much of the picture as possible should be in focus. Depth of field depends here on the distance and the film format, but even more so on the aperture and the focal distance.
The film format
The format is determined by your camera. The size of the sensor and/or of the film here influences the focal distance and thus also the depth of field. Smartphones and small consumer cameras have even smaller sensors than 35mm format. Professionals therefore tend to prefer to use medium or even large format cameras.
The focal distance
The greater the focal distance of a lens, the smaller its depth of field and vice versa. A wide-angle lens accordingly offers more sharpness in the entire picture than a telezoom or the 85 millimetre lens - which is popular for portraits.
If you increase the distance to your motif, the focus range becomes larger. The closer you move to your motif, the smaller the depth of field becomes. If you use a compact camera in portrait or macro mode, you can utilise these to produce more blurring.
Example: the main motif is five metres in front of the camera and the aperture remains the same at f5.6, so the depth of field is only a few centimetres long with a focal distance of 105 millimetres. With a focal distance of 28 millimetres, by contrast, the range that appears sharply in focus is already more between one metre in front and two metres behind the focussed motif.
The further you close the aperture, the greater the depth of field becomes. At the same time, the overall sharpness also increases. Above a certain aperture, which varies from lens to lens, the overall sharpness decreases again, while the depth of field continues to increase. So: the higher the f-number (smaller aperture opening), the greater the depth of field.
Because the amount of light striking the sensor/film decreases when the aperture is closed, you must, if necessary, increase the exposure time. With increasing exposure time it is recommended to also use a tripod.
Although what you focus on in the picture only has an influence on depth of field if you switch between a close object and a distant object, manual focussing already has an influence on your picture design.
The depth-of-field preview button as an aid
In order to be able to judge depth of field correctly when focussing, many cameras have a depth-of-field preview button, because the depth of field is otherwise not usually correctly shown in the viewfinder or on the display. If you do not have this option, you can simply check depth of field by taking some test shots.
Simply put, this is a point from which, with a particular focal distance and aperture, everything further away from that point is photographed with sharpness. This hyperfocal distance often plays an important role in the genre of landscape photography - where even when the light would be sufficient, a tripod is normally used in order to be able to control the aperture entirely independently from the exposure time.
Depth of field with your mobile
You can also achieve the effect with mobile phone photos which lack depth of field due to their small sensors and lenses. Here it is helpful to get very close up to the main motif and focus on it manually or to add the missing three-dimensionality or depth effect afterwards. Many apps, such as e.g. „BigLens“ for iOS or „AfterFokus Pro“ for Android, make it possible to add blurring to photos afterwards.