To: atmlist 
From: Mark Suchting 
Cc: atmlist 
Reply-To: Mark Suchting 


At 12:06 PM 10/12/2002 -0800, Mel Bartels wrote:


>  However, the primary was
>closer to spherical than parabolic.

I remember reading somewhere that the Astroscans could only be recoated by
Edmund because the asphere was actually achieved by an uneven deposition of
the Aluminium coating, using a profiled rotating shutter in the coating
chamber. The corespondent discovered this upon consultation with Edmund
after he removed the coating and the `figure' inadvertently.

The Vixen 200mm F9 Cassegrains apparently have a difficult aspheric profile
on the primary or secondary by the same means.

~Mark Suchting

--- BBBS/NT v4.00 MP