I think that you would want a constant distance from a simple lens to the
surface so that the sun will always be in focus. This would result in a
concave spherical surface bearing the analemma, with the lens at its center.
However, if you prefer a flat surface, I think that you can use a
photographic lens, these being designed to image onto flat surfaces.
Gordon Uber
San Diego
At 17:53 12/7/04, Aten Heliochronometers wrote:
Hello group, I am new here, but have been reading the posts for a few days.
I have a question for the group, I am designing a new heliochronometer
(afterwards to be referred as a "helio" for brevity) and I am striving for
a bit more accuracy. Roughly, I intend to try and cast a point of light
on a surface that contains an analemma. Should I create the analemma on a
flat or bowl shaped surface? In other words would it be more accurate to
project the analemma onto a plane or a section of a concave sphere? I am
mainly concerned with the 47deg. motion of the sun over the course of the year.
TIA for any thoughts
Dave G.
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