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Spot Image Size Using f-Number

If two objects imaged by a camera are separated by an angle small enough that their Airy disks on the camera detector start overlapping, the objects cannot be clearly separated any more in the image, and they start blurring together. The closest separation of the images of two objects on the film before significant blurring occurs is the spot image size.

The spot image diameter is proportional to the f-number times the light wavelength.

Formula

QuantityVariable["d", "Diameter"] == (2*BesselJZero[1, 1]*QuantityVariable["N", "Unitless"]*QuantityVariable["λ", "LightWavelength"])/Pi

symbol description physical quantity
d spot image diameter "Diameter"
N f­number "Unitless"
λ light wavelength "LightWavelength"

Forms

Examples

Get the resource:

In[1]:=
ResourceObject["Spot Image Size Using f-Number"]
Out[1]=

Get the formula:

In[2]:=
FormulaData[ResourceObject["Spot Image Size Using f-Number"]]
Out[2]=

Use some values:

In[3]:=
FormulaData[ ResourceObject[ "Spot Image Size Using f-Number"], {QuantityVariable[ "\[Lambda]","LightWavelength"] -> Quantity[530, "Nanometers"]}]
Out[3]=

Source Metadata

  • Creator:
  • Date: 1835

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