A camera photographs a distant brick wall of radiance

PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Geometrical optics and imaging · Geometrical optics and imaging

Optics and Photonics, Ch Radiometry and photometry

Problem

A camera photographs a distant brick wall of radiance L=45 W m−2 sr−1L = 45\ \text{W m}^{-2}\ \text{sr}^{-1}. For a lossless lens and a distant, matt object, the sensor irradiance is Iimage=πL/(4f#2)I_{\rm image} = \pi L/(4f_\#^2). ((a)) Find the sensor irradiance at f/2.8f/2.8. ((b)) Find the sensor irradiance at f/8f/8. ((c)) Confirm that the ratio of the two matches (f# ratio)2(f_\#\text{ ratio})^2.

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