Asahi Pentax ES Operating Manual Excerpts
DEPTH-OF-FIELD GUIDE
If you want to know how great the depth of field is at a certain aperture, look at the depth-of-field guide. In the above photograph, the distance scale scale is set at 5 meters…the lens is focused on a subject 5 meters away. The calibrations on each side of the distance index correspond to the diaphragm setting and indicate the range of focus distance for different lens apertures. For example, if the lens opening of f/4 is to be used, the range on the distance scale ring covered within the figure 4 on the depth-of-field guide indicates the area
in focus at the lens opening. You will note from the depth-of-field guide in the photograph that the range from approximately 4.5 to 6.5m is in focus. Note that as the lens apertures change, the effective depth of field also changes. For the depth of fields at different apertures and distances, refer to the next page.
Depth of field is the range between the nearest and farthest distances which are in focus at different lens apertures.
Reproduced for Historical and Reference Purposes by Paul M. Provencher http://whitemetal.com Not For Resale.