Re: ATM off axis newtonians.

[Anthony Stillman <atmer@flash.net>]

Having today been flamed by another member of the ATM list regarding this
thread.  I feel I must elaborate.

The relevant portion of my post appears to have been:

Anthony Stillman wrote:
>If you have a lot of light (the Moon, the planets), it can be fun to play
>with apodizing masks.  I think the square ones are the most interesting,
>given their curious transfer properties.


As I have previously written about this and it appears in the archive, this
is redundant, however...

Square apodizing masks do have curious transfer properties.  Namely, the
modulation transfer function parallel to an edge of a square aperture is
superior to the MTF parallel to a diagonal.  Further, the MTF parallel to
an edge is superior to the MTF of a circular aperture with diameter equal
in size to the length of square's diagonal.  That is, it is possible to
improve resolution, in the mid-frequencies, along two axes, by apodizing a
circular aperture with a square mask.

Finally, while I would not have thought to put this way, I suppose it is a
miracle.


Anthony

Mazel tov