In article , Richard Schtzl <Richard.Schaetzl@xxxxxxxxxxxxxxxxxxxx>
writes
>Kennedy wrote:
>
>> The diffraction limited cut-off frequency of a lens is given by
>> Wo = 1/(L * f/#)
>> where Wo is the cut-off frequency in cy/mm at the focal plane
>> and L is the wavelength in mm
>>
>> Thus, for an f/32, the cut-off frequency of the diffraction limited
>> optic is 62.5cy/mm at the focal plane, assuming a mean wavelegth for
>> visible light of 600nm.
>>
>> This is independent of focus distance, magnification or whether there is
>> an 'r' in the month. :-)
>
>Independent of Magnification so far only for the "real or effective
>aperture", because the effective aperture (in contrary to the choosen
>aperture on the aperture ring) will get smaller with higher
>magnification.
>
>For example: choosen aperture = 5,6 effective aperture at 1:1 = 11
>
True - I missed that!
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's pissed.
Python Philosophers (replace 'nospam' with 'kennedym' when replying)
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