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> Defend your position, and is it easy to swap mirrors?

Rather than quote my sources verbatim, read the opinions of Ken Gebhart and
David Burch online:

http://celestaire.com/page8.html

http://www.starpath.com/catalog/courses/cel_faqs.htm#full-view

The gist is some light is lost (not reflected) by a two-way mirror.  Making
horizons and stars harder to distinguish at twilight.  The blue cast can
also make horizons harder to distinguish in less-than-ideal conditions.

As the owner of Celestaire, Ken has well-established credentials as a pilot
and navigator using cel nav.   David is also well respected and has his own
school.

As to my opinion of Celestaire's business practices, it is based on many
dealings.  If there was a mistake made no argument, they take care of it
pronto--no beating around the bush. Never an argument of "small print"
quote.

As to buying new, it would appear that all the Astra IIIB models now come
standard with what was the "deluxe" index mirror (front silvered).  It was a
$40 option.  So at $400 for a used unit without a front silvered index
mirror, you are probably paying about what the seller paid for the unit when
new.

>and is it easy to swap mirrors?

If you just swap out mirrors in the frame, it could be a bit painful,
especially as you would have to go back and forth adjusting index error and
side error every swap.

You can purchase a mirror in frame for the Astra for a few sawbucks more
than the mirror alone (approx. $70 in frame).  Then it is a breeze.  Just
remove two screws, replace it with the other frame/mirror, and replace the
screws.  Ken suggested that one should barely snug up the screws, and wiggle
the frame around until index error is minimal, then finish tightening the
screws.  That's all there is to it.  If side error was already adjusted
once, you should not have to mess with again.

Hope that helps,

Bill

   

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