Re: Comparisons for Beginners

From: Canopus (canopus56_at_yahoo.com)
Date: 10/31/04 

Date: 31 Oct 2004 13:56:17 -0800

"Alan French" <adfrenchremoveallthis@nycap.rr.com> wrote in message news:<1H5hd.58452$l07.49191@twister.nyroc.rr.com>...
> "Alson Wong" <rasvp@yahoo.com.b_l_o_c_k> wrote in message
> news:10o8fnfmunclve3@corp.supernews.com...
> > "Alan French" <adfrenchremoveallthis@nycap.rr.com> wrote in message
> > news:sHWgd.31802$JS4.21425@twister.nyroc.rr.com...
<snip>
> > > Anyone know of a site that shows a comparison of what
> > > folks could expect to see through different apertures? <snip>
> I wonder if anyone has done something showing how an object or two
> would actually look.

As to websites, Roger Clark, author of the advanced amateur and expert
level classic book _Visual Astronomy of the Night Sky, Cambridge Press
1990_, has a website with static gifs and animated gifs of the
eyepiece view of M51 simulating, separately, increasing aperture and
magnification:

http://www.clarkvision.com/visastro/index.html
http://www.clarkvision.com/visastro/m51-apert/index.html
http://www.clarkvision.com/visastro/m51-mag/index.html

Ioannis Galidakis, an occassional poster in this Usenet group, has
done an excellent series of comparative sketches of common Messier
objects through a 11x80 Chinon binocular, an 20x100 Apogee binocular,
and a Tasco 60mm/700mm@35x refractor:

http://users.forthnet.gr/ath/jgal/astronomy/Simulation.html

Matt Weir developed an eyepiece telescope simulator, which included
Jupiter, Saturn, Mars, the Moon and the Pleadies. Formerly, it was
distributed as a Web freeware application. In 2003, Weir took this Web
application offline and moved it to shareware distribution. One
freeware site remains online with a full functioning version of his
telescope eyepiece simulator mini-app:

http://www.scopesim.com/

The simulations of Jupiter and Saturn are particularly useful for
rapidly varying aperture and magnification (using slider-bars), and
for illustrating the resulting changes in image relative brightness
and observable detail. With practice, you can quickly change to
settings (aperture and magnification) that simulate a 20 x 200mm fl
binoculars, a "first-scope" 70mm f/7 refractor, a 3.5" inch f/8
reflector, a 6"-8"-10" f/5 DOB, and a Celestron SCT, with lenses of
varying focal lengths. It's a good "hands-on" simulator that newbie's
can play with in order to get a grasp of the applicable optical
principles.

The full-functioning version is available as a shareware download for
$15, e.g. -

http://downloads-zdnet.com.com/3000-2054-10205556.html
http://www.download.com/3000-2054-10205556.html

Use search terms "Weir telescope eyepiece simulator" at any search
engine.

As to hardcopy books available at the local library, IMHO the best
recent book in this category is:

Star Watch: The Amateur Astronomer's Guide to Finding, Observing, and
Learning About over 125 Celestial Objects
by Philip S. Harrington, Philip S. Harrington Wiley; 1st edition (July
18, 2003) ISBN: 0471418048
http://www.philharrington.net/
http://www.amazon.com/exec/obidos/tg/detail/-/0471418048/qid=1099254152/sr=1-3/ref=sr_1_3/103-4829691-3527847?v=glance&s=books

Harrington goes through a top 100 list and gives a description of the
type of detail that would be seen through a pair of 10x50 binoculars,
a small refractor at moderate magnification, and an amateur class (6
to 8 inch) DOB. The book contains many excellent hand-sketches using
varying magnifications and instruments (binos, small scopes, etc), but
does not include a comparison series of photos or sketches of the same
object at different apertures and magnifications. I often refer to
this book when explaining to beginner friends, what would be seen
through varying telescopes.

As to the "choosing a scope" article discussed above in this thread,
Sky & Telescope has a good "choosing the first telescope" article:

http://skyandtelescope.com/howto/scopes/
http://skyandtelescope.com/howto/scopes/article_241_1.asp (choosing a
telescope)
http://skyandtelescope.com/howto/scopes/article_256_1.asp (choosing
binoculars)

as does Bill Ferris's classic "Cosmic Voyage" website:

http://members.aol.com/billferris/firstscope.html

Orion telescope's ( www.telescope.com ) "Product selection wizard",
also is a pretty good tool to guide beginner's through a series of
questions on selecting a first scope.

IMHO, the best "buying a telescope" article online is one written by
"starlord", a frequent poster in this thread, along with a number of
contributors including David Knisely:

http://home.inreach.com/starlord/

Starlord's advice to measure the backseat of your car and buy the
largest aperture DOB that will comfortably fit in the back seat of
your car is one of the more humorous and common-sense pieces of
astronomy advice that I have read on the net. -:)

Enjoy - Canopus

P.S. -

1) You mentioned that you were already aware of various online sources
for sketched objects. My favorite is Bill Ferris's overwhelming
lifetime collection of sketches, which I mention only for other
readers of this thread:

http://members.aol.com/billferris/deepsky.html

2) For references to online Web Java applications that simulate lenses
and telescopes, see Usenet thread:

sci.astro.amateur
Re: Prove that Fo/Fe = magnification
2003-7-02
news:<9865fa0b.0307021903.5acb3d3@posting.google.com>

These Java Web apps are useful for explaining to beginners how light
travels through a telescope and how lenses work.

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