Posted by
Joachim Wesner on
Oct 03, 2006; 9:30am
URL: http://imagej.273.s1.nabble.com/More-on-pixel-shifting-tp3701425p3701427.html
Hi,
>When the filter is off-camber it does not matter whether the rays are
>parallel or a different shape, it will always results in a shift.
>
>It is all about the optical axis and the angle of each component of the
>optical system with respect to this axis.
>
>Simply get a pen and paper and you will see what happens when you place
>the filter under an angle with respect to the rest of the optical axis
>(system).
Nope, a tilted (otherwise ideal, i.e. both faces parallel) filter will
cause
a slight lateral offset of any ray that passes, but, after the tubelens,
those
rays will hit the very same image spot as whithout the filter - only from a
slightly different direction. That "immunity" (within limits as vignetting)
to extra optical components in the ray path is just what "infinity optics"
is all about.
>By the way, if the filter is off-camber you will also face the problem
>of chromatic shift, meaning that the light transmitted through the
>filter will shift to other wavelengths.
Chromatic shift does not imply that the wavelength of the light changes!!!
JW
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