Depth of field versus film format size
As the equations above show, depth of field also related to the circle of confusion which is a figure of merit associated with each type of film format. Larger imaging devices (such as 8x10 inch photographic plates) have a larger circle of confusion, while smaller imaging devices such as point-and-shoot digital cameras have a smaller circle of confusion. All else being equal, depth of field is inversely proportional to the film format size.
In practical terms this means that smaller cameras have deeper depth of field than larger cameras. This can be an advantage or disadvantage, depending on the desired effect. A large format camera is better for photographs where the forground and background are blurred (cf. bokeh), while a small camera maximizes depth of field, so that objects behind or in front of the focus plane are still in good focus.
15 ธ.ค. 48 09:59:32