4 ms·
Long time since I did any optics but this basically just convolution. The impact at the output plane of dust/imperfections on the lens is (approximately) a 2D f
by _paulc 12y ago
Long time since I did any optics but this basically just convolution. The impact at the output plane of dust/imperfections on the lens is (approximately) a 2D fourier transform of the dust/imperfections. If you have a single dust particle (essentially an impulse) on the lens this will be convolved into a dc response at the focal plane.
[1] http://en.wikipedia.org/wiki/Fourier_optics#Fourier_transforming_property_of_lenses http://en.wikipedia.org/wiki/Fourier_optics#Fourier_transfor...
- darkmighty 12y agoIt's approx. convolution and the impulse response varies with the distance to focal plane: at focal plane it's impulsive but near the lens it's quite flat (almost DC -- it's simply a "zoomed in" aperture, which is a big circle usually).