Re: Newb Q: M31 (Andromeda) In an 8'' Newt

From: XxXxXxX (xxxx_at_xxxx.com)
Date: 08/26/04 

Date: Thu, 26 Aug 2004 10:41:43 -0400

"Jon Isaacs" <jonisaacs@aol.com> wrote in message
news:20040826092546.19052.00004725@mb-m06.aol.com...
> The field of view is determined by field stop diameter of the eyepiece and
the
> focal length of the telescope. The internal baffling of the scope can
also
> restrict the FOV. The maximum field stop possible is the Inner diameter
of
> the 1.25 in eyepiece barrel. This means that with a Plossl design the
maximum
> FOV is reached with a 32mm so that a 40mm eyepiece will have no greater
FOV.

Cool, did not know that... so why would they bother selling a 40mm eyepiece
in a 1.25 inch format? a 2 inch format would make more sense based on that
tidbit.

> But I have gotten good high power views with the 130mm F5 Newtonian, last
> spring, Saturn was sharp, the Cassini clear and sharp with subtle shading
> evident on the planet. I see no reason that a 130mm F5 Newtonian
shouldn't
> provide sharp on-axis views and since it has a smaller central obstructon,
> (29%) it seems reasonable that it would at least provide comparable high
power
> views to the MAK.

I've heard a lot of people "dis" the short tube newtonians (mind you I've
also heard a lot of people "dis" anything that isn't a 12" or larger Dob).
Is there anything to that? I hadn't considered a short tube newt before.

> But at F5 and a 650mm focal length, 20x with a 32mm Plossl and a 2.5
degree are
> available, this is a dimension that is lacking in the ETX-125. Sweeping
the
> Milkway with this scope is a real treat.

Well I can safely say that last week with the ETX-60 and near perfect
conditions (perfect for a suburb that is) I had hours of fun just slewing
across the sky. Maybe I should just stay with the ETX-60 and my 90mm MAK
rather than go for something that combines the two (which would be closer to
an 130mm Newt like the Celestron 130 you mentioned)?

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