Yes, perhaps you should read that document. Green edges around highlights are a textbook example of LoCA.
But if the lens is stopped down one stop (charts on the bottom and above on the right-hand side), the reversal point of the longitudinal spherical aberration is excluded and the brightness profiles look pleasant again. In this example we can also see that the brightness profiles become flatter when the image is blurred more.
In reality the brightness gradient at the edge of the blur circle is not as high as shown in above charts. They had been calculated for a single wavelength, but in reality different colours have different circles, which makes things a bit more smooth. Real lenses have as well a longitudinal chromatic aberration; the focus of the rays depends on the wavelength.
Yes, perhaps you should read that document. Green edges around highlights are a textbook example of LoCA.
But if the lens is stopped down one stop (charts on the bottom and above on the right-hand side), the reversal point of the longitudinal spherical aberration is excluded and the brightness profiles look pleasant again. In this example we can also see that the brightness profiles become flatter when the image is blurred more.
In reality the brightness gradient at the edge of the blur circle is not as high as shown in above charts. They had been calculated for a single wavelength, but in reality different colours have different circles, which makes things a bit more smooth. Real lenses have as well a longitudinal chromatic aberration; the focus of the rays depends on the wavelength.
Yes, perhaps you should read that document. Green edges around highlights are a textbook example of LoCA.
But if the lens is stopped down one stop
(charts on the bottom and above on the
right-hand side), the reversal point of the
longitudinal spherical aberration is excluded and the brightness profiles look pleasant
again. In this example we can also see that the
brightness profiles become flatter when the image is blurred more.
In reality the brightness gradient at the edge of the blur circle is not as high as shown in
above charts. They had been calculated for a single wavelength, but in reality different colours have different circles, which makes things a bit more smooth. Real lenses have as well a longitudinal chromatic aberration; the focus of the rays depends on the wavelength.
Aug 27, 2011 at 11:30 PM
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