Re: New telescope, only see a big blur.
From: Robert Cook (rbrtck_at_hotmail.com)
Date: 09/02/04
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Date: 2 Sep 2004 13:39:06 -0700
Edmund Rishekl <edrishekl@yahoo.com> wrote in message news:<dnbcj0l1d4a1f2nia59tc5khb7h4omjhs1@4ax.com>...
>
> From the telescope I then remove the unit that holds the eyepiece. It
> is labeled "3X BARLOW LENS". It is a black tube aprox. 6" long which
> is narrower at the end which goes inside the telescope and terminates
> in a lens.
There are good Barlow lenses available, but this one is useless--it's
only there to *theoretically* provide the very high magnification that
Tasco advertises, but in practice, you might as well throw it away
(seriously). If you remove it from the tube that moves when you turn
the focusing knob (called the "drawtube"), you should be able to
insert either eyepiece into the drawtube directly (don't forget to
secure it in place). Before you do this, however, make sure that you
can see a reflection of your eye when looking into the center of the
empty drawtube. If you can't see it or it is poorly centered, then
your telescope's mirrors need to be "collimated" (aligned):
http://www.google.com/search?hl=en&ie=UTF-8&q=collimation
You'll eventually need to do this anyway, but if you can at least see
a fairly well-centered image of your eye, then you can proceed with
trying to get your telescope to provide viewable images. Your
telescope's "focal length" is 500mm. To find out what magnification
you're getting, divide the telescope's focal length by the focal
length of the eyepiece you're using. For example, the H20mm (the "H"
stands for the design type) eyepiece will give you 500/20 = 25x. This
is considered low magnification (nothing bad about that), and is good
for viewing many of the larger objects in the sky, as well as
initially finding the smaller objects. The SR4mm eyepiece will give
you 125x, which is considered fairly high magnification, but because
of its design, don't expect much from this eyepiece--for now, only use
the H20mm, inserted directly into the drawtube. You should at least
be able to focus the image now.
By the way, your telescope comes with a 5x24 finder, which is a small
telescope with very low magnification and a wide field of view,
providing an intermediate step between your eyes and the main
telescope to help you aim at specific objects. Unfortunately, because
this type of finder is so cheaply made, it may hurt as much as it
helps. If you have trouble locating objects through this finder,
place your eye behind the telescope and aim along the tube instead.
- Robert Cook
- Next message: eric bazan: "Re: RAT NOTES - TEC 200 F9 Triplet Apochromat - 09/01/04"
- Previous message: AA Institute: "Re: Interstellar Propulsion idea using an Asteroid and a few comets!"
- In reply to: Edmund Rishekl: "New telescope, only see a big blur."
- Next in thread: Robert Cook: "Re: New telescope, only see a big blur."
- Messages sorted by: [ date ] [ thread ]
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