At 16:24 10.12.01, joel Wilcox wrote:
I think I now understand why it is important to stop down in order to get
a good diffraction star. One wants to take advantage of the larger role
that diffraction will have on the image. But couldn't this explain
differences between lenses and their ability to make diffraction
stars? If one lens is "poorer" at the smaller stops because of
diffraction, mightn't it be "better" at making diffraction stars?
Yes, sort of, but remember that lens test show the sum of all errors, not
just diffraction. If your lenses used round aperures only, you'd expect
them to show the same amount of diffraction at the same f/-number,
regardless of focal length. Fewer blades (and an even number of them.
Example: 7blades=14spikes, 8blades=8spikes) would however show fewer but
brighter diffraction spikes.
Regards,
Thomas Bryhn
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