ATM 16" F/33 valid design?

[Dominic-Luc Webb molmed <Dominic.Luc-Webb@molmed.ki.se>]

Attention focal length extremists...

This matter of sanity in focal length choice comes up
periodically. I recall The Simak paper in Astronomy
magazine in April 1984 mentioning that focal length
of 120" was chosen for one of the major observatories
because it was effectively the upper limit for the
conditions  at this site, located on prime observing
real estate presumably. I leave it to the readers to
decide whether they agree with this very general statement.
On a lot of the nights I have observed, even this seemed
useless to me, so I never gave much serious thought to very
long scopes and could not think of any major discoveries
made with such Earthbound scopes that we ATM mortals
would have access to (i.e., ATM scopes).

The February issue of S&T is out and there is an
articule there about Emile Schaer's telescope and
the "F" ring of Saturn. I have not seen this ring
through any scope, but it seems Schaer did, with
a 16" F/33 Cass (i.e., fl = 528"). Interesting
thought... I have an 18" mirror, soon to become
a slow Newtonian. Maybe its actually justified to
core this beast and give it a Cass secondary, with
a system EFL around F/30. I guess I could still use it
as a Newt. On the other hand, I guess Schaer, being
Swiss, might have had access to exceptional real
estate for that scope, like the Swiss Alps, not to
be compared to the Swedish Alps.

:)


Cheers,



Dominic

North 59 37' 30"
East  17 48' 10"