For David Millier

A complex discussion - very interesting to see the points of view. Roland makes a telling point or two.

Firstly, the mention of Nyquist should never be made in sentence involving random arrangements of twigs at a great distance and we should firstly know why that is so. Anyone who does not know why should leave the room and write out 1000 times "Nyquist is in the spatial frequency domain, the home of the humble sine wave" or something like that.

Secondly, a single line seen at a great distance, can be quite visible in an image - as is well-known in a separate but related area, that of the "point spread function" and it's cousin, the "line spread function" which itself ican be calculated from the "edge spread function" (slant edge test per ISO).

Such a line is visible in a similar way that stars are visible in night sky. An intense source of light, many, many times smaller than 1 minute of arc in size actually becomes a blob (we all know why) on the sensor and hence visible in an image. So it is that distant lines (may I say pine needles?) in their turn, given sufficient contrast at their point of origin will also appear - will they not - and they will be real.

It's like, along the tree-line, there are a good few impulse functions all waiting to excite a pixel or two on your Merrill . . .

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Regards,
Ted http://tcktek.blogspot.com
SD10/70mm macro