The depth of field indicates the range in which images are displayed sharply when photographing or scanning. For example, if you work with a shallow depth of field and focus on an object that is, say, 30 cm away from the lens, everything closer (15 cm) or farther away (35 cm) will appear out of focus.
When digitizing, however, one works mainly with flat, two-dimensional originals, for which a shallow depth of field is supposedly required. However, if you want to digitize three-dimensional objects, such as books with a deep book fold or seal letters with a structure, it quickly becomes clear why a high depth of field is necessary: here, all areas should be displayed sharply and legibly so that no information is lost.
The further away the lens is from an object, the greater the depth of field. In macro photography, where the distance between the optics and the subject can be less than 5 cm, it is self-explanatory that the depth of field decreases accordingly or is barely present.
Thanks to the special optics and the area sensor used, our systems are able to provide a depth of field of 8-15 cm, depending on the format.