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Date: 13 Dec 2006 12:21:42
From: James Harris
Subject: Zoom astro telescope with good optics
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Is there such a thing as an astroscope with zoom? To minimise shake the
zoom would have to be on a decoupled wheel (preferred) or electric. It
would be a great way to navigate around the sky and to close-in on
binaries, especially multicoloured ones such as Albireo.
I'm not thinking of a 'toy' telescope but a proper one with decent
optics.
Any thoughts?
--
James
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Date: 13 Dec 2006 15:00:32
From: W. H. Greer
Subject: Re: Zoom astro telescope with good optics
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"James Harris" <james.harris.1@googlemail.com > wrote:
>Is there such a thing as an astroscope with zoom? To minimise shake the
>zoom would have to be on a decoupled wheel (preferred) or electric. It
>would be a great way to navigate around the sky and to close-in on
>binaries, especially multicoloured ones such as Albireo.
Hi James,
As Brian pointed out, zoom eyepieces are available. Such eyepieces
are manually adjusted and are the closest option to an astronomical
telescope with zoom. (It may be only a matter of time before
electrically controlled zooms become readily available.)
For navigational purposes wider true fields (than can be had with
typical zoom eyepieces) can be achieved with an appropriate,
low-power, wide-field eyepiece. I find eyepiece swapping to be more
effective for navigating and "zooming in" than the use of a zoom
eyepiece. Such swapping gives me better control over field size, a
wider range of magnifications (higher highs and/or lower lows), as
well as control over other issues relating to eyepiece quality.
When a telescope is shaky, the problem almost always lies with the
telescope's mount and/or tripod. For an astronomical telescope that
is adequately mounted it's usually possible to swap one eyepiece for
another with very little or no noticeable shaking.
--
Bill
Celestial Journeys
http://cejour.blogspot.com
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Date: 13 Dec 2006 17:54:58
From: Dennis Woos
Subject: Re: Zoom astro telescope with good optics
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> For navigational purposes wider true fields (than can be had with
> typical zoom eyepieces) can be achieved with an appropriate,
> low-power, wide-field eyepiece. I find eyepiece swapping to be more
> effective for navigating and "zooming in" than the use of a zoom
> eyepiece. Such swapping gives me better control over field size, a
> wider range of magnifications (higher highs and/or lower lows), as
> well as control over other issues relating to eyepiece quality.
>
My sons and I really like zooming in on globular clusters with our TV 8-24mm
zoom in our 10" f/6 dob. In fact, we also let the more interested folks at
public events zoom in and out on stuff, as the TV is mechanically smooth
enough and the 10" dob heavy enough so that the target usually stays put.
Dennis
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Date: 13 Dec 2006 12:31:29
From: Brian Tung
Subject: Re: Zoom astro telescope with good optics
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James Harris wrote:
> Is there such a thing as an astroscope with zoom? To minimise shake the
> zoom would have to be on a decoupled wheel (preferred) or electric. It
> would be a great way to navigate around the sky and to close-in on
> binaries, especially multicoloured ones such as Albireo.
>
> I'm not thinking of a 'toy' telescope but a proper one with decent
> optics.
Telescopes for astronomy have separate eyepieces, so what you would want
is a zoom eyepiece. There are a few good ones, some of which are more
or less the same eyepiece, rebadged. (Or at least used to be.) Vixen
still makes, I believe, an 8-24 mm edition; on the shorter end of the
range, Tele Vue makes a well-regarded 3-6 mm zoom (but you have to pay
through the nose for it). For the sort of navigation you're talking
about, you would probably want the 8-24 mm zoom, is my guess.
The zoom eyepieces are not mechanically decoupled at all. This doesn't
really affect their use, for most people, since they are not used for
the motion effect of zoom in real time; instead, they are used as
eyepieces with a variable focal length, so you can obtain different
magnifications without switching eyepieces.
--
Brian Tung <brian@isi.edu >
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html
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