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f-Number Arithmetic

The f-number of an optical system, such as a camera lens, is the ratio of the system's focal length to the diameter of the entrance pupil. It is a quantitative measure of lens speed.

The resultant f\[Hyphen]number equals the original f\[Hyphen]number times 2 to the power one-half the f\[Hyphen]stop increment.

Formula

QuantityVariable[Subscript["N", "2"], "Unitless"] == 2^(QuantityVariable["δ​F", "Unitless"]/2)*QuantityVariable[Subscript["N", "1"], "Unitless"]

symbol description physical quantity
N2 resultant f­number "Unitless"
δ​F f­stop increment "Unitless"
N1 original f­number "Unitless"

Forms

Examples

Get the resource:

In[1]:=
ResourceObject["f-Number Arithmetic"]
Out[1]=

Get the formula:

In[2]:=
FormulaData[ResourceObject["f-Number Arithmetic"]]
Out[2]=

Use some values:

In[3]:=
FormulaData[ResourceObject["f-Number Arithmetic"], {QuantityVariable[ \!\(\*SubscriptBox[\("N"\), \("1"\)]\),"Unitless"] -> 5.6`}]
Out[3]=

Source Metadata

  • Contributor:
  • Date: 1867

Publisher Information