Re: Why not Rigel?

Art posted:

> I have been pondering the pros and cons of the Rigel verses Telrad finders.
>
> Because of the smaller footprint and lighter weight I lean towards the Rigel.
>
> Is the advantage of the three ring Telrad target enough to change my choice?
> How do you feel about one over the other?

Not to "steal" my own thunder (article on it will be appearing on CloudyNights 
soon), but the main advantages of the Telrad are that it has a 3-ring reticle 
and its window is larger than that of the Rigel.  This makes it a little 
easier to do extended star hops, and also makes eye positioning less critical 
than the more tight requirements of the Rigel (you often have to have your eye 
almost right behind the Rigel's little window just to see the reticle).  The 
Rigel also shows a small amount of parallax as you move your head around (the 
rings move a bit), while the Telrad shows better performance here with zero 
visible parallax.  The Rigel rings also become slightly distorted at long eye 
positions and the parallax becomes worse.  The Rigel is smaller and lighter 
than the Telrad, but it is also made of a thinner grade of plastic than that 
used in the Telrad (easier to break).  The Rigel's tiny acrylic window is only 
glued down on one end, so the window can be more easily broken out of its 
housing by accident, either in storage by something like a loose pen or 
pencil, or by a finger during operation.  The window is tiny and set inside a 
small housing which can make cleaning it a little more of a chore.  Its hood 
provides slight dewing protection, but unlike the Telrad, you can't easily 
wipe the window off if dew forms on it.  The Telrad's window is made of hard 
glass, so a simple cloth can be used for cleaning, and there is no hood to get 
in the way (although this also means that an external dew shield is needed). 
That having been said, I have a Rigel on my 100mm f/6 refractor and a Telrad 
on my 10 inch f/5.6 Newtonian.  Both are useful, although for the most part, I 
do like the Telrad just a bit more.  Clear skies to you.
--
David W. Knisely  [EMAIL PROTECTED]
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

**********************************************
* Attend the 11th Annual NEBRASKA STAR PARTY *
*    July 18-23, 2004, Merritt Reservoir     *
*      http://www.NebraskaStarParty.org      *
**********************************************