Aperture curve
Aperture curves are curves drawn on zoom lenses that show the dependence of the depth of field on the focal length for various f-stops . They are used to determine the focus area and the hyperfocal distance . The curves are plotted on the surface of the lens in a two-dimensional diagram of focal length and object distance . Two curves are drawn for each f-number shown , one for the near point and one for the far point . In most cases, aperture curves are only drawn for a few selected f-numbers, the assignment of the curves to the f-numbers is usually done by color coding.
example
Zoom lens 28-80mm: (left in the picture) | |||||
---|---|---|---|---|---|
Set distance: 1.2 m | F-number | Focal length | |||
28 mm | 35 mm | 50 mm | 70 mm | ||
Focus range (in m) | 22nd | 0.6 - ∞ | 0.7-3.4 | 0.9 - 1.7 | 1 - 1.4 |
8th | 0.9 - 1.9 | 1 - 1.6 | 1 - 1.4 | 1.1-1.3 | |
hyperfocal distance (in m) | 22nd | 1.2 | 1.8 | 3.7 | 7.3 |
8th | 3.3 | 5.1 | 10.5 | 20.5 |
Zoom lens 80-200mm: (on the right in the picture) | ||||||
---|---|---|---|---|---|---|
Set distance: 10 m | F-number | Focal length | ||||
80 mm | 100 mm | 135 mm | 150 mm | 200 mm | ||
Focus range (in m) | 22nd | 4.9 - ∞ | 6-30.5 | 7.3-15.8 | 7.7-14.2 | 8.6 - 12 |
16 | 5.7-39.1 | 6.8-19.1 | 7.9-13.5 | 8.3-12.7 | 9-11.3 | |
11 | 6.5-21.1 | 7.5-15.1 | 8.5-12.3 | 8.7-11.7 | 9.2-10.9 | |
hyperfocal distance (in m) | 22nd | 9.5 | 14.8 | 27 | 33.3 | 59.1 |
16 | 13.4 | 20.9 | 38.1 | 47 | 83.5 | |
11 | 18.9 | 29.6 | 53.8 | 66.4 | 118.1 |