Re: [APML] Coma Berenices Barndoor

[George Anderson <georgea@cam.org>]

Eric

You may want to include a description of things like film used, lens
focal length and field stop, and exposure time on your web page.
On a basic barn door the limit (before visible trailing occurs) for
exposure is around five minutes with a 35mm lens, this time can be
increased (almost double) by allowing the elevation bolt to pivot at
both fastening points. This gives you an isocolese (sp) triangle instead
of a right angled triangle. The isocolese triangle gives a closer
approximation of the rotation that you are trying to achieve.

George Anderson
Montreal Canada

Clear skies and good health

Eric Beard wrote:
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