Re: [ATM] more on cassegrain baffling...

[Andy Saulietis <iss@pvtnetworks.net>]

Benoit writes,


>
>Currently, to have a fully shielded/illuminated field, the central
>obstruction goes
>to 0.31 for a 10 arcmin field... I would like to increase the usable
>field to 20 arcmin
>but do not like what it does to central obstruction (goes up to 0.34)

Why not just add a removable  annulus to your secondary mirror
to increase the obscuration ratio *when* you need total
baffling?

My 16" f15.6 Nasmyth Cass has an obscuration ratio of 40%
to get a totally baffled but unvignetted field of 2 inches
diameter (30 arc min). Visually I can't tell the difference
between this and the scope in Newt config with a 4.5" dia
secondary..photographically it wouldnt matter either.


Andy Saulietis
ISS Enterprises
10 Milky Way
Mayhill NM 88339


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