|
Forum: Pentax SLR Lens Discussion
01-04-2015, 03:28 AM
|
| |
It's for depth of field indeed:
On film or a film-size sensor, you get approximately the depth of field shown by those numbers. Usually they start at f4 in the center, with a limited dof. The higher the number (the more you close the diaphragm), the more depth you have: from the distance directly above the f/number on the left to the distant above the f/number on the right.
On zoom lenses, you'll see that the depth of field scale is not parallel to the barrel but opens slowly as the focal length is shortened.
|
