The depth of field is defined as an area that can be considered “focused” or “sharp” in the frame and is a factor that has a decisive effect on appearance photography. The sharpest area in each photo is the area on which the camera focuses and everything on the same plane, that is, the same distance from the camera. As the distance from the focus point increases, the photo will appear blurred and less sharp. This is true both for parts located in front of the focus point and for areas beyond it.
If we take the whole sharp area of photography, it would seem that the division of depth of field is like this: one third of the sharp area, the one found in the depth of field will found before the focal length and the other two thirds after it. For each lens at any focal length, a change in the value of the aperture will also lead to a change in the depth of the field: the higher the value of the aperture will be (closed shutter), the depth of field will increase, and i.e. the area that is in focus and will be considered “sharper” will be larger. On the other hand, the smaller the aperture (a smaller aperture value), the smaller the depth of field, i.e., the smaller area of the photograph will be focus and the rest will gradually blur: the farther away from the focal point, the more blurred.
Therefore, the selection of aperture must take into account the area you want to include in the sharp and focused area of the photograph. Lenses with a different focal length will give different depth of field at the same aperture value: wide angle lenses (short focal length) especially the fish eye, will provide depth of field greater than lenses with medium focal length and depth of field much larger than what you get with macro lenses.
As a rule, the longer the focal length of the lens, the smaller the depth of field will be unlike the ones of a lens with a shorter focal length and a smaller given aperture. Another factor that affects depth of field is the distance of the camera of the object you are shooting: the smaller the distance from the object, the greater the depth of field. If so, shooting at a short distance, at any given focal length, will reduce the depth of field you will receive, compared to shooting at a greater distance at the same focal length.
To summarize the depth of field, the three factors that affect the depth of field are:
- The aperture value: When this value is high, the depth of field is large and vice versa.
- Focal length: When this value is small (wide angle lens) the depth of field is large and vice versa.
- Distance from the object: When the distance from the object is greater the depth of field is greater and vice versa.