Gaining Minutes Of Daylight

All points of each plane in a scene converge at points that are contained in the corresponding image plane. In the accompanying figure, although not explicitly depicted, the plane of the scene that passes through the point P has a corresponding image plane through the point P '. When using the focus ring, what we are doing is to vary the distance between the plane in which the sensor is located (so-called focal plane) and the plane of the lens. (NOTE: The focal plane is located on focal length F ', only when focused at infinity).
This leads to select one of the planes in the scene so that its image plane is formed in the focal plane. In this plane will be called the focal plane. In our image the focal plane is passing through P and the image plane passes through P '.
Depth of field is the set of planes before and after the plane of focus forming circles in the focal plane images below in size to the circle of confusion. Due to limited human vision, we observe on the image to be perfectly clear, even when in fact, perfectly clear, there is only one: the focus plane. Therefore, and importantly, the depth of field refers to the planes of the scene, in particular those who appreciate sharply. The attached figure
this definition of Depth of Field is manifested in a slightly different way. Here we take the planes A 'and B' as those in the circle formed by the cone of light rays converge in P 'and then diverge again has the size for the circle of confusion. From these image planes can provide that depth of field is limited by the corresponding planes A and B, of which A 'and B' are flat image. It is important to note that the definition of depth of field is underway in Actually, depending on the depth of focus.
The summary is that although the first definition is considered to be more common in the literature on photography, the second is more simply helps us understand what is happening in diagrammatic form. Obviously the two do not cease to be two sides of the same coin.