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Purchasing Amateur Telescopes FAQ by Ronnie B. Kon

In Part II

7. Where Do I Buy My Telescope?

7.1 What About Buying Used?

7.2 What About Building A Telescope?

8. What Accessories Will I Need?

9. What are Digital Setting Circles?

10. Why Should I Start With Binoculars?

10.1 How Do I Hold Binoculars

11. What Books and Star Charts Are Recommended?

11.1 What About Computer Programs?

11.1.1 What Programs Can I Get For Free?

12. About this FAQ

 

7.  OK, Where Do I Buy My Telescope?

Well, there are three basic places:

A Store
     Yes, the obvious--you find a store (NOT a department store) which
     sells  telescopes and write a check (or, if they won't give you a
     cash discount, use a credit card that offers buyer protection, or
     gives you bonus miles, or some such).

     The advantages of this method  is  that  you  have  someplace  to
     return  the  telescope  to  if  you  have problems with it.  Some
     places even offer your money back if you change your mind  within
     some  grace  period.  The 'droids that work in the store may even
     attempt to offer some advice.  My experience is that this is usu-
     ally 100% wrong, but that's actually as useful as advice which is
     always correct, but you have to know to invert the sense.

     The disadvantage is that you generally pay more for the telescope
     itself, and you pay sales tax.



Mail Order
     There are two sorts of mail order: the discount stores that  sell
     all  sorts  of  stuff through the mail, and telescope stores that
     sell through the mail in addition to selling from their store.

     The advantages and disadvantages of mail order are  obvious:  you
     cannot  take the merchandise back easily if something goes wrong,
     but it's cheaper (and you probably pay no sales tax).



Other People
     You can find some great deals in used  telescopes.   Many  people
     buy  expensive telescopes, use them two or three times, get bored
     and sell them.  The advantage is strictly monetary: you pay  sig-
     nificantly less (and, of course, no tax).

     The disadvantage is that you are buying something "as  is"--which
     you  may  want  to  think  twice about doing if you are buying an
     expensive telescope.  Also, both Meade and Celestron offer  (lim-
     ited)   lifetime  warranties  on  their  optics,  which  are  not
     transferable.

All that having been said, here is a list of places you can buy  tele-
scopes,  with  comments as applicable.  Note that all will sell direct
or will ship.

Orion Telescopes
P.O. Box 1158
Santa Cruz, CA  95061
(also San Francisco and Cupertino)
800-447-1001
sales@oriontel.com


Orion Telescopes carries a wide selection of  binoculars,  telescopes,
and  accessories  (Celestron, Tele Vue, and their house brand; they do
not carry Meade).  They have a  30  day  "no  questions,  satisfaction
guaranteed"  refund  policy, which they do seem serious about.  A fair
number of people (myself included) have bought at Orion  and  all  are
very  satisfied  with the way they were treated.  This place is fairly
expensive, and they have the unfortunate policy of charging a  "stock-
ing  fee" if you buy from the store, which always seems to be the same
as the postage and handling fee for mail ordering from their catalogue
(which they will send you for free if you call them).



Lumicon
Livermore, California
(see S&T or Astronomy for Address)


This is where I ended up buying  my  telescope.   No  complaints,  but
there  really  was no opportunity for anything to go wrong: I drove up
knowing exactly what I wanted and what their price was, paid by credit
card, and drove my new telescope home.  And it is not all that impres-
sive that they had it in stock--I bought one of the most popular tele-
scopes around at the time.


Astronomics
(see S&T or Astronomy for address)
Norman, OK


Higher prices than Adorama and Focus (see below), but lower than Orion
and  Lumicon.   Enthusiastically  recommended by a couple of people on
the net.  As with all mail order, make  sure  the  shipping  price  is
included.


Pocono Mountain Optics
(formerly Wholesale Optics of Pennsylvania)
(see S&T or Astronomy for Address)


Not to be confused with Pauli's Wholesale Optical in Danbury, CT  (see
below).   Enthusiastically  recommended  by  a  few people on the net.
Owned by Glenn Jacobs who goes to most of the astronomy  get-togethers
in  the  NY-NJ-PA-CT  area so you actually meet him if you live in the
area.  Often willing to cut a package  deal  if  you  are  buying  big
ticket  items.  No problems returning things with which you are dissa-
tisfied.


Roger Tuthill
(see S&T or Astronomy for Address)


Enthusiastically recommended by a person on the net.   Not  the  least
expensive,  but top-notch service.  Roger unpacks, inspects and colli-
mates every 'scope he sells, and is very  good  about  refunding  your
money if you are dissatisfied.


University Optics
(see S&T or Astronomy for Address)


A few people have reported using University  Optics,  and  all  report
receiving good service.  I have heard no complaints.


Kenneth Novak & Co.
(see S&T or Astronomy for Address)
A couple of respondants have bought accessories  from  here,  and  are
very happy with them.


Parks Optical
(See S&T or Astronomy for Address)


A couple of people have mentioned that shipment can be pretty delayed,
but  the quality of their equipment appears to be high, and improving.
Salespeople vary from knowledgeable to bubble headed.


Adorama
42 West 18th Street
New York, NY  10011
orders: (800) 223-2500
info:   (212) 741-0052


Along with Focus Camera (see below), the lowest prices you will  find.
Expect  no  dealer  support,  and make sure you find out how much they
will charge for shipping before placing your order.  And pray that the
optics arrive intact.  I really would recommend that you not buy tele-
scopes from these guys.  Eyepieces and other accessories, however, are
probably worth the risk if the price difference is significant.


Focus Camera
4419-21 13th Avenue
Brooklyn, NY  11219
orders: (800) 221-0828
info:   (718) 436-1518


Refer to Adorama.  Same comments apply.


Pauli's Wholesale Optical
Danbury, CT


A fair number of people on the net  reported  having  bad  experiences
with  these  people.   The  most  common seemed to be being lured into
driving 4 or 5 hours to the  showroom  and  then  being  treated  very
rudely.  Only one person seemed even moderately happy with them.


7.1.  What About Buying Used?

Think long and hard before spending a lot of money  on  a  used  tele-
scope.   You  will not have a warranty, and you have no assurance that
the optics are in good shape.  If you decide to buy used, get  a  sub-
scription  to The Starry Messenger and/or The Cosmic Exchange and look
at their ads.  Also check your local paper for classified ads  selling
telescopes--this  is  where you will find your best deals, as they are
selling to the smallest audience.

It appears that most people  want  to  get  about  75%  of  list  when
advertising  in the astronomy rags (Starry Messenger, S&T, etc).  This
is probably not enough of a discount to make it  worthwhile.   If  you
can  find  something at 50% of list, you might want to think about it.
You certainly want to see the telescope before you buy.  A used  tele-
scope is just as good as a new one if it's been properly stored, tran-
sported and used.  A little dust on the optics is generally a sign  of
a  telescope  which  hasn't  been cleaned frequently, which is usually
better than one which has.  Get the May 1990 issue of Astronomy  maga-
zine which had an article on star testing a telescope (Test Drive Your
Telescope by Dick Suiter).  If you don't live close to the seller, try
to get someone from the net to go inspect the telescope for you.  (You
probably want to send them the money in this case and get them to ship
it  for  you.   This  is  a major imposition, please note, so you will
probably have to do some serious begging to talk anyone into  it,  but
it lessens the chance of fraud).

7.2.  What About Building A Telescope?

This section was written by Andy Michael.

We just took a rather unusual approach to getting  a  beginning  tele-
scope:  we took John Dobson's telescope building class and built an 8"
and a 12.5" reflector on Dobsonian mounts (of course).  We  went  this
way  for  a  few  reasons:  to  get large aperture for seeing deep sky
objects and higher magnification with good resolution when compared to
small  refractors  in this price range, to keep the price down, and to
soak up John's wit and wisdom.  The down side is that these telescopes
are  not suited for astro-photography (at least not without building a
different mount) but that didn't bother us.  Also they are large.  The
8"  tube  we broke into two pieces for easy portability, but the 12.5"
one will probably go on the roof rack.  These are about f/7 telescopes
so  the tube lengths are 56" and 7' respectively.  Of course, when you
build yours you can make whatever size you want.  On  the  other  hand
you can pack your clothes in them; try that with an SCT.  The cost was
about $250 for the 8" telescope, $450 for the 12.5"er plus about 24 to
30  hours of work and 16 - 24 hours of class.  It's a challenging pro-
ject but the first time you focus  on  something  with  a  mirror  you
ground is an incredible thrill.  Another benefit is that we now know a
lot about telescope design and if we ever have problems with  them  we
know how to fix them.

If you don't have access to John's (or other  peoples')  classes  then
you  can  try  building  one  by  reading his book and by watching the
video.  Our class was the first to see parts  of  the  video  and  had
great  success at finishing the telescopes fast and without needing to
correct the mirrors very much.  Coincidence?  Class consensus was no.

The book (excerpted from the order form):  "How  and  Why  to  Make  a
User-Friendly  Sidewalk  Telescope" by John Dobson with Norm Sperling.
To appreciate why Dobson makes each  factor  just  so,  learn  how  he
thinks  about  it.   His  philosophy of star-gazing perfuses his tele-
scopes and his book. The book includes the  only  detailed  biography;
wonderful  vignettes  from the Sidewalk Astronomers' many expeditions;
their own special way of describing celestial objects; and, of course,
complete  details  for  making  a  Dobsonian.   169  pages; 154 clear,
friendly line drawings; 9  photos.   Hardbound  in  plywood,  Dobson's
favorite material.  Exclusive source.  Send $39.95 + $5.00 shipping to
Everything in the Universe, 185 John Street, Oakland, CA 94611.

Rumor has it that there is a 90-minute  video  in  which  John  Dobson
shows  how  you  can build your own low-cost Dobsonian Telescope.  The
video is a complete step-by-step guide,  covering  telescopes  from  8
inches  to  16  inches in diameter.  $39.95 + $3.50 shipping.  This is
not available from the Everything in the Universe store.


8.  What Accessories Will I Need?

In addition to a telescope, you absolutely must have a mounting and  a
tripod.  You will also need a few eyepieces--a telescope with only one
eyepiece is like a piano with one key.

These accessories don't come cheap--expect to  pay  as  much  for  the
mounting  and  tripod  as  you paid for the optical tube.  For a first
telescope, you probably will want to buy an entire system--it tends to
be less expensive that way.  It is also easier.

Which eyepieces should you start with?  I'd  suggest  three  or  four,
maybe  a  30mm,  25mm,  20mm, 8mm and a 2x Barlow (which will give you
coverage of 30, 25, 20, 15, 12.5, 10, 8, and 4 mm).  Buy eyepieces  of
like  quality  to your telescope.  Putting a $300 Nagler eyepiece on a
$150 telescope is pointless (it  would  also  probably  tip  over  the
entire telescope).


9.  What Are Digital Setting Circles

This section was written by Jim Van Nuland

9.1.  What Are They?

Digital Setting Circles (DSCs) are a small special  purpose  computer,
mounted on or near a telescope.  The scope has shaft encoders attached
to sense the motion of the scope's axes, and the  computer  then  con-
verts  these motions to the position of the telescope, and displays it
(for instance)  in  Right  Ascension  (RA)  and  Declination.   An  8-
conductor  cable  runs from the computer to the encoders, with 4 wires
to each encoder.  RJ-45 telephone connectors are used at the computer.

They do NOT move the scope.  You push it by hand, and  the  DSCs  tell
you which way to move and how much.

What makes DSCs so desirable  is  that  they  work  on  alt/az-mounted
scopes;  and,  even  with equatorial mountings, it is not necessary to
polar align the mount.  (However, it's desirable to have the mount  at
least roughly polar-aligned so it follows an object.)

Additionally, most models have an internal catalog and a "guide" mode.
One selects an object (or, in some, a planet), and the DSCs tell which
way to move each axis.

They are marketed by Lumicon, Jim's Mobile, Inc., Celestron, and Orion
Telescope  Centers.   The  various  brands and models differ mostly in
their internal  catalogs  of  celestial  objects.   All  are  actually
manufactured  by  the  same company, Tangent Instruments of Palo Alto,
California, USA, who, however does not sell directly  to  individuals.
I  own the NGC-MAX from JMI, so some of my statements may not apply to
other versions.


9.2.  Must the ground board be leveled?

No.  An alt/az mount must have a fiduciary mark such that the tube can
be  placed accurately at 90 degrees to the elevation axis.  One way to
do this is to (one time only) level the ground board, then  the  tube.
Make  the mark in such a manner that it can be adjusted when something
changes.  Some models of DSCs allow an alt/az mount to be  initialized
in  a vertical position.  When starting the DSCs, the tube must be set
horizontal (or vertical), and then two stars are used to  align.   The
stars  must be at least 20 degrees apart in the sky (90 is ideal), and
the first may not be Polaris.


9.3.  How does one set up an equatorial mounting?

If the mount is known to be accurately polar aligned,  you  may  still
use  two  stars  as  mentioned above.  Or you may set the DSCs to take
advantage of the known alignment, and it will require only one object,
and no zero degree reference mark is needed.

If an equatorial mount is not polar aligned, it must have a  reference
mark  at  zero  degrees  declination, and must use the two-star setup.
For a German mount, the mark may be on either side of the scope  (tube
pointing east or west), and the DSCs set to correspond.  The mount may
be driven or undriven.  As for an alt/az mount, the stars must  be  at
least 20 degrees apart, and the first may not be Polaris.


9.4.  Do the DSCs support a Poncet platform?

Probably depends on the model.  The NGC-MAX provides telescope type ET
(equatorial  table).   It assumes that the table is carrying an alt/az
scope, and that the scope is initialized with the tube horizontal.   I
believe  that an equatorial mount could be used, but have not tried to
simulate it.


9.5.  How accurate is the device?

The position of the scope is displayed to one  minute  of  RA  and  10
minutes  of  dec.  Guide mode displays position error to 0.1 degree of
arc.  The actual accuracy depends on the care with which the alignment
was  done, the accuracy of the mounting, accuracy with which the shaft
encoders were installed, the resolution of the encoders, and a bit  of
luck.   If  the  level or zero was not set accurately, the system will
work poorly, and it should be re-started.  If star settings were  done
carelessly, one can simply re-do one or both of them.

The "luck" factor stems from the digital nature of the shaft encoders.
If  the  encoder  is  on  the verge of a step, you could be off by one
step.

The absolute theoretical resolution is three encoder  steps,  assuming
everything  else  is  perfect.   In  practice,  I get about 0.2 to 0.3
degrees, and closer near the alignment stars.  If I move  a  long  way
across  the  sky,  the  error is perhaps 0.5, but then I re-align on a
convenient nearby star.  It's not too unusual to get 0.1  if  all  has
gone especially well during alignment.  This with 4000 step encoders.

Accuracy is best between the alignment stars, and the DSCs calculate a
"warp" so as to spread out the error.  When re-aligning, only one star
sighting is needed.  The DSCs retain only  the  two  most-recent  star
settings, provided they are at least 20 degrees apart in the sky.

Some models allow alignment on ANY catalog object, which  is  helpful,
but  I  find  that accuracy is best on stars or very round objects.  I
find that planetary positions are especially  suspect.   The  computer
carries  only the date, not the hour.  (Use UT date.) I have often had
poor alignments when using planets, and do so only for  daylight  set-
ups; I re-align on stars as soon as I can find any.  Open clusters are
especially unreliable; galaxies are not much better.


9.6.  What objects are in the internal catalog?

This is the major difference between models.  All  have  a  few  dozen
named  stars,  used  especially  for initial alignment.  Some have the
planets.  The Lumicon models have  a  catalog  of  planetary  nebulae,
which is Dr. Jack Marling's specialty.

The NGC-MAX version 3.94 (July, 1992) has the planets; 28 user-defined
objects;  the  Messier catalog (including M40 and M110); the full NGC,
including the so-called "non-existent" objects; about half of  the  IC
catalog; a catalog of 951 interesting stars (multiple, red, variable);
and a list of 367 additional deep-sky objects, many of which are  very
faint.

For each object, the catalog has the position, magnitude, size (diame-
ter  or  separation),  constellation,  name  (if  any)  and/or catalog
number, and the type of object.  Some have a word or two  of  descrip-
tion.  This probably varies with the brand and model.


9.7.  May I add my own objects?  Comets, for instance?

The NGC-MAX accepts user objects, and I presume  most  other  high-end
models  do  as well.  I like to put in the Sun and Moon, so that I can
align during the day.  This must  be  done  carefully,  with  the  Sun
filter  attached.   THIS  IS  DANGEROUS, as the filter must be removed
when sighting on the Moon, and if you come back to the Sun,  you  MUST
have  first  re-attached  the  filter!   The  moon is a poor alignment
object because it has up to a degree of parallax, and it  moves  about
0.5  degrees  per hour.  But it provides a start, and it may be enough
to locate some bright stars, and re-align.


9.8.  What is "identify" mode?

Identify mode is present in the NGC-MAX, and  probably  other  models.
One  specifies  the  class of object, and the faintest magnitude, then
the DSC selects the nearest to the telescope's position.   Very  nice,
but in the Realm of Galaxies, alignment is critical and then there are
too many to be certain.  To check, read out the magnitude and descrip-
tion, and go to Guide mode and see how far away the object is.

It's especially useful in clouds, as one may point the  scope  into  a
clear  spot,  then ask what is nearby.  One must separately search for
galaxies, clusters, etc.

Identify mode runs continuously, so that, as the scope is  moved,  the
DSCs will (after a few seconds), indicate the new (or nearest) object.


9.9.  Can it replace star charts?

For comparatively easy objects, probably.  In  a  crowded  field,  no.
Some  models support the Tiron Atlas 2000 and the Uranometria 2000, by
indicating, for each object, the page on which it (the object) will be
found.   These  models  also  indicate  the chart corresponding to the
position of the scope, regardless of specific object.


9.10.  What other functions are present?

This varies heavily with model.  The NGC-MAX (here we  go  again)  has
two that have not already been discussed.

"Timer" counts up in hours, minutes, and seconds.  It can be  stopped,
reset,  and  re-started,  but  can't  be restarted without first being
reset.

"Encoder" shows the encoder positions in degrees.  If an alt/az  scope
was  pointed north when the DSC was powered up, then encoder mode will
read elevation and azimuth, if the scope is also  standing  reasonably
level.


9.11.  How is it powered?  How long does the battery last?

There is an internal 9-volt transistor battery.  The load is 18 to  40
mA  (NGC-MAX), depending on how bright the display is.  I suppose this
might depend on the model, too.  The maker claims 30 to 50 hours on an
alkaline  battery.   They  do  last a good long time.  There is a "low
battery" indicator which would turn on at  about  4.5  volts,  but  in
practice, I get "encoder error" messages before that.

Some models have a second connector (serial port) by which external  9
-  15  volts  DC  may be supplied.  This does not require the internal
battery to be removed; the two supplies are in parallel with diodes to
prevent back-circuits.  It does not recharge the internal battery.


9.12.  How accurately SHOULD the mount be constructed?

The brief answer is, as accurately as you'd like the DSCs to  operate.
For  an  equatorial  mount,  there must be little flexure; the RA axis
must be perpendicular to the dec axis, which in turn must  be  perpen-
dicular to the optical axis of the tube.

For an alt/az mount, the ground board must be rigid, the azimuth bear-
ing  surface  must be flat, dent-free and stiff; and the side bearings
must be the identical height, that is, the elevation and azimuth  axes
must  be  accurately  perpendicular.  In addition, the optical axis of
the tube must be perpendicular to the elevation axis.  There is a ter-
rible  irony  here:   the  Dobsonian mount works precisely because its
kinematically stable design does NOT require  that  it  be  accurately
constructed!


9.13.  How accurately should encoders be installed?

Again, the short answer is, as accurately as you'd like  the  DSCs  to
operate.   One can't do the job with a hand-held drill.  OTOH, careful
work with a modest lathe and drill press is  quite  sufficient,  espe-
cially  if performed by a modest machinist.  Most astronomy clubs have
such a person.

Best accuracy is obtained  with  high-resolution  encoders.   Standard
encoders  have  2048 steps per revolution, and high-res type has 4000.
One can also use gears to provide greater resolution, but see below.

If the encoder is connected directly to a shaft, the hole in the shaft
must  not  be  oversize.   It  must  be  straight,  well centered, and
parallel to the axis.  The body of the encoder must be held so that it
cannot rotate with the shaft.  If it is connected by gears, the shafts
must be parallel, and there must be no backlash.

Encoders are not especially delicate, but they do not like to be bent.
They  require  very  little  torque,  and  rotate  continuously.   The
setscrew should not deform the shaft.  The 4-wire connector should  be
looped  so  it does not pull on the encoder.  They may be mounted such
that the shaft is stationary, with the body moving, or the usual  way;
the direction is set in the DSCs' setup option.

In an alt/az mount, the azimuth encoder is typically mounted atop  the
center  bolt.   In this case, the bolt must be nicely perpendicular to
the ground board, and the comments about shaft mounting (above) apply.
If  the  rocker box has any side play, it will be nearly impossible to
avoid some runout.  This can be reduced by using a very long lever arm
to hold the body of the encoder.

Both side  bearings  must  be  round  (especially  the  one  with  the
encoder),  the center must be carefully located, and the encoder shaft
parallel to the elevation axis.  Any runout here  will  cause  serious
inaccuracies when moving across the sky.


9.14.  How accurately MUST the mount be constructed?

Please don't feel that only a million dollar  mount  can  be  equipped
with  DSCs.  My 1972 Optical Craftsman (German) mount works very well,
even with about 0.5 degrees of error  if  I  shift  the  mounting  and
return  to an object.  This was the economy model!  A machinist friend
helped me drill the holes for the encoder shafts.

I used UGMA grade 10 precision gears to step up the dec  shaft  speed.
The designer of the DSCs was amazed at that, and admitted that he used
UGMA 4 with adequate results.  I don't know how to calculate how  much
more accuracy I might be getting from my expensive gears.

My alt/az mount, crafted of wood in my shop with only hand tools, car-
ries  a  108mm  f/4  scope, and *always* puts an object in a low-power
field.  OTOH, if I re-collimate the scope, I must also re-position the
vertical mark.  I usually re-align after moving far across the sky.

If the mounting is less than perfect, it means that you will  need  to
re-align more often.  But if the mount is *really* sloppy, it probably
will not be satisfactory.


9.15.  Can I connect the DSCs to my own computer?

Yes, for some models.  The NGC-MAX, and probably others, has a  serial
port  that  may  be used with an external computer, so that the screen
shows a dynamic star map, identifies objects, etc.

But the attached computer must take over ALL functions, including  the
prompting  for  "level  me,"  pointing  at particular alignment stars,
guiding, calculating the conversions for RA and Dec,  etc.   I  under-
stand  The_Sky,  from  Software  Bisque, does all this, but I have not
seen it in use nor heard from a live user.

The port is a modular telephone connector (RJ11).  It has four  wires:
B+, data in, data out, and ground.  External to the NGC-MAX, the cable
must route DTR back to the attached computer as DSR, CD,  and/or  CTS,
as  needed by the attached computer.  The 4th wire is +Battery, a 9 to
15 volt external power supply, which does not charge the internal bat-
tery.  It is not necessary to remove the internal battery,

When the NGC-MAX is operating  in  "BBOX"  mode,  it  blanks  its  own
display, and does nothing but pass the shaft encoders' values over the
serial port.  It multiplies them by the encoder ratios (the latter set
in the NGC-MAX setup function), and scales them such that 00000 is the
position at power-on, and 32767 is just under 1 rotation.

Communication is at 9600,8,N,1.  When the NGC-MAX powers on, it  sends
a  hello  message such as "V2.94".  When the attached computer sends a
character (the sample program uses "Q" but  anything  seems  to  work)
down  the port; and the NGC-MAX replies with 13 characters of the for-
mat "+00000t+00000" where the "t" is ASCII 9, and the 00000s  are  the
two encoder values.

I don't use this facility, but I'm too curious not to have  tried  it.
I  used  my modem program to supply the computer side.  I use the NGC-
MAX whenever I'm doing general observing, and I  like  it  very  well.
But  I  don't  have  a portable computer to use with it, and don't too
much see the need.  OTOH, if I fell into a laptop, I'd surely want  to
try connecting them.


10.  Why Should I Start With Binoculars?

The quick answer is because you already have them, so you do not  have
to  spend any money.  Certainly going right out and buying the Fujinon
25x150 Astronomical Binocular ($11,000 list price) would be  a  pretty
stupid thing to do, no matter how good the binoculars are.

You should also avoid the quick-focus binoculars, as they are easy  to
de-focus as well.

The remainder of this section was written by Paul Zander.

Based on my experience, I suggest that you start with a pair  of  7x50
binoculars.   This  is  the  most popular size and hence good ones are
available from many stores, even some of the discounters.  Be sure  to
get ones that have anti-reflection coatings on the mirrors and lenses.
If you wear eyeglasses, you may be able to find binoculars  which  can
focus  without  them  (unless you have significant astigmatism).  Make
sure the image is sharp at the center and edges at the same time.

"7x" is the magnification.  Most people can hand  hold  these  without
needing  to  bother  with tripods, etc.  The "50" means 50mm (~2 inch)
objectives (aperture).  This gives light gathering ability similar  to
many  small telescopes.  Many advanced star gazers regularly use bino-
culars to either locate items to focus telescopes on, or just for  the
wider field of view.

When trying to view near the zenith, use a reclining lawn lounger: you
can  lie  back  and  support your arms on the chair, giving a steadier
view. You also will not get a crick in your neck.

You might also use a plastic pad to lie on.

10.1.  How Do I Hold Binoculars?

This section was written by Jay Freeman.

If you don't have a tripod (and tripods are sometimes a little clumsy,
and are often difficult to use when the binocular is pointing near the
zenith), it is important to know how to hold a binocular correctly  to
achieve maximum steadiness.

The way most people tend to hold a binocular is with one hand on  each
side of the middle of the body--roughly where the prisms are in a con-
ventional 7x50, say, so that the left hand is directly to the left  of
the center of gravity of the instrument and the right hand is directly
opposite it, to the right of the center of gravity.

For most people, there is a better position.   Imagine  that  you  are
holding the binocular to your eyes, with your hands positioned as just
described.  Now, slide your hands along the body  of  the  instrument,
toward  your  face,  until only your pinky and ring fingers are curled
around the back end of the binocular  body.   In  this  position,  the
binocular  feels  a  little  nose-heavy, because you are supporting it
behind its center of gravity.

Now curl each thumb up as if you were making a  fist,  and  flex  your
hands  so  that  the  second  bone  in from the tip of your thumbs are
pressed up against your cheekbones (counting the bone in the  part  of
your  thumb  where the thumbnail is, as the first bone).  This makes a
quite solid structural connection between the body of  the  binocular,
through your hands and thumbs, to your face, and markedly improves how
steadily you can hold the instrument.  Similarly, curl the  first  and
middle  fingers  of  each hand around the corresponding binocular eye-
piece, to provide a little more  structural  connection  (and  perhaps
also  some protection from stray light).  In this position, your hands
are not far from where they would be if you brought them to your  face
to block out stray reflections while peering through a store window at
night.

For most people, this position leads to markedly steadier viewing, but
if  the  binocular  is  especially  long and heavy (say, a 10x70 or an
11x80), the out-of-balance position can  be  quite  tiring.   In  that
case,  move  *one*  hand  out  to the objective end of its side of the
binocular, so that you are supporting the instrument on opposite sides
of  its center of gravity, but with some structural connection between
it and your face; namely, the other hand.  When the hand way out there
gets tired--just switch hands.

For each person, there is a limit to how heavy and / or how powerful a
binocular  can  be,  before there is no way for that person to hold it
steady enough.  I am an averaged-sized adult male in reasonable physi-
cal condition, and I find I can hold a 10x70 (Orion's) steadily enough
to use indefinitely on astronomical objects.  But I have an old Celes-
tron  11x80,  that doesn't look much bigger or heavier than the 10x70,
that I can only use for a few minutes before my arms get tired.  As  a
12-year  old  I  am sure I could have used a 7x50 indefinitely with no
problem, but at a younger age I might have had  difficulty  using  one
continuously.   Your  experience may vary with your strength, size and
condition.  Try before you buy, if at all possible.

10.2.  What Are Some Eye Relief Figures?

If you need  to  wear  eyeglasses  while  looking  through  binoculars
(presumably  you have astigmatism, but if you require many diopters of
correction you might need to as well) you  need  reasonably  good  eye
relief.  Dana Bunner contributes the following table:

      Model                     Advertised ER     Measured ER
      Bausch & Lomb 7x26 Custom       16               15
      Celestron 10x50 Pro             15               10
      Celestron 7x42 Ultima           23               19
      Celestron 7x50 Ultima           20               16
      Celestron 10x50 Ultima          19               17
      Celestron 8x56 Ultima           21               11
      Fujinon 8x40 BFL                19               17
      Fujinon 7x50 FMT-SX             23               20
      Fujinon 10x70 FMT-SX            19               17
      Minolta 7x50 Standard           18               16
      Minolta 10x50 Standard           ?                9 (FYI)
      Minolta 10x50 XL                18               16
      Nikon 8x30E Criterion           13               13
      Nikon 7x50 Windjammer           16               16
      Optolyth 10x40 Touring          13               12
      Pentax 8x24 UCF                 13                8
      Pentax 7x35 PCF                 14                9
      Pentax 7x50 PCF                 20               10
      Swift 8x25 Micron               13               11
      Zeiss 7x42 B/GA T Dialyt        19               18
      Zeiss 20x60S                     ?               14 (FYI)



11.  What Books and Star Charts Are Recommended?

If you don't know the constellations, you might want a book that  will
help  you  learn them.  A "fun" book for those just learning the stars
is The Stars, A New Way of Seeing Them by H.  Rey,  which  presents  a
non-orthodox  way  of drawing the constellations so they are easier to
visualize.

You will probably want a beginner's guide, such as the book by Sherrod
mentioned above.  Sky Publishing has some introductory materials which
would probably be as useful, which you get for free when you subscribe
to Sky and Telescope.

Petersen's Field Guide to the Stars and Planets  comes  highly  recom-
mended.   It  is very inexpensive ($13), small and handy to use at the
telescope. It has a good discussion about stars, planets, nebulae, and
galaxies; and has a very complete albeit small-scale star chart, along
with a the usual tables. It has long lists  of  deep-sky  objects  for
each area of the sky.

You will need a bigger star chart than is included in Petersen's.  Try
Sky  Atlas  2000.0, by Wil Tirion.  The field edition, which has white
stars on a black field, is probably more useful than the  desk  guide.
It  is  also printed on heavier paper, so is more resistant to dew and
the rigors of the night.  For beginners, buying Uranometria 2000.0  is
probably  a  mistake.  Yes, it is the "best" star chart, but the scale
is impossibly  small--when  the  Orion  constellation  takes  up  four
separate pages it is really hard to use for beginners.

Burnham's Celestial Handbook ($36).  This three volume set  is  billed
as  "An  Observer's  Guide to the Universe Beyond the Solar System"--a
rather all-encompassing claim, which it manages to live up to.  Infor-
mation  on  every  item of interest you can think of: galaxies, double
stars (optical and binary), variable stars, nebulae, etc.  More infor-
mation than you could use in a lifetime.  I consider this a necessity.

Sky and Telescope's 100 Best Deep Sky Objects.   About  $5,  which  is
kind  of  expensive  for a list, but it sure makes it easier to figure
out what to look at when you are just beginning.  The items are sorted
by  Right Ascension, which makes it real easy to figure out which ones
are currently up.

All the materials listed are available from:

                Sky Publishing Corporation
                P.O. Box 9111
                Belmont, MA 02178-9918 USA

Their catalog is free. See also in our Shop


11.1.  What About Computer Programs?

There are basically two types of astronomy programs:  calculations  of
astronomical  things  and  computerized star charts.  I don't consider
either of them worth buying as a tool to help  an  observer.   On  the
other  hand,  some of them (particularly the star charts) can be a lot
of fun to play with during the day or on cloudy  nights.   Before  you
buy  any,  you should probably check out the ones available on the net
(see next section).
For a good example of the variety of  programs  which  will  calculate
things,  look  for  Zephyr  Software's  ad  in  Sky and Telescope (or,
presumably, Astronomy).  They list two pages of  programs,  for  about
$60  each,  which  can  calculate things like solar eclipses, or lunar
phases, or ephemerides, etc.  To my mind, your money would  be  better
spent on eyepieces, or a bigger telescope to begin with.

As for computerized star charts (usually $100 - $250),  these  can  be
very  nice.   Most  will  draw in the constellation lines if you like,
will let you click a mouse on an object to have  it  identified,  find
objects  by  name,  and so forth.  Also, the fact that they can scroll
the sky is much nicer than having to turn pages in  a  printed  chart.
The  fact that they can show the stars as they are tonight, as opposed
to a fixed time (such as 2000.0) is so pointless as to  be  laughable.
The  only  problem is that you will probably never be able to use your
computer at your telescope, which means that  this  is  something  you
will  use  indoors.   This strikes me as a nice recreation, but again,
you would be better served by spending the money  on  a  better  tele-
scope.

As for recommendations for programs, both Dance of the Planets ($200),
and  The Sky 4.1 ($75 - $175, depending on the size of the database of
objects) tend to get rave reviews in the magazines.  Both are only for
IBM PCs and compatibles.  The former is available from

A.R.C Science Simulation Software
P.O. Box 19558
Loveland, CO  80539
(303) 667-1168

The latter is available from

Software Bisque
912 12th St.
Suite A
Golden, CO  80401
(303) 278-4478


For the Macintosh, a program called Voyager is the  dominant  program.
David Nash comments that:

1)  It has a lot of features for the planets.The accuracy of its posi-
tions  probably  isn't  as  great  as some more dedicated program like
Dance of the Planets, but it is  more  than  sufficient  for  ordinary
observers.   And it does a lot:  in addition to the standard "plot the
planets against the stars" mode,  you  can  get  conjunction  searches
(handy  for  finding  eclipses), planets displayed with disk and phase
indicated, a "tracking" mode that plots planet positions  at  a  given
interval  (say,  steps  of  2  days or 1 month), and a bunch of little
features that come in handy, such as a  program  that  produces  those
magnitude  -  vs - time and angular size - vs. time plots that you see
in the astronomy magazines.

2)  NICE interface compared to most programs I've seen, including  Mac
programs  like  MacAstro,  but  then  again that is shareware and less
fully-featured. Each starchart has Mac-style scrollbars on  each  side
--  one for RA (or Azimuth) and one for Dec (or altitude).  This makes
navigating around the sky fast and simple -- grab the scroll bars  and
you're  off  and running.  Similar sorts of controls allow you to zoom
in on a region (down to 1 deg. x 1 deg.).   Much  more  flexible  than
The_Sky for the PC (the DOS version anyway -- I haven't tried the Win-
dows version, so this may not be an entirely fair comparison).

3)  Many options for plotting charts.  You can get them in  equatorial
(RA/Dec) or local horizon (alt/az) coordinates (or several others, but
these are the most useful).  A little counter in  one  corner  of  the
screen  tells  you  what  the  coordinates  of  the  cursor are in the
appropriate modes.   You can add coordinate grid lines, mark important
points or areas (zenith, horizon, ecliptic, etc.).

4)  Miscellaneous fun stuff: a 3-D map of the ~50 or so nearest  stars
to  the  Sun  (click on the axes to change the view), an "orrery" mode
that shows the Solar system from above, making it easy to  see  plane-
tary relationships (conjunctions, oppositions, etc)

It also has a fairly comprehensive deep-sky database.

The only really big drawbacks here are that the program is  black  and
white only, even on color Macs, and the star database is a bit limited
compared to many programs (esp. some for the PC).  There is,  however,
a new version which supports color, and adds more stars.




Brian Cuthbertson has a program HyperSKY, which he was kind enough  to
send  me  to  review.  Unfortunately, the first disk was corrupt, so I
could not load it onto my computer.  However, from the brief  instruc-
tion  list  he sent it appears to do what you would expect a computer-
ized star chart to--zoom, pan, identify objects, is  mouse-based,  and
so  on.  (Yes, I know that I don't have much here to base a review on,
but:  1) he is on the net, and I admit to a net.bias; and 2)  he  said
nice things about my FAQ and sent me a free copy of his program).

HyperSKY is available from Willman-Bell publishers (see ad in any copy
of S&T or Astronomy).

A correspondent recommends the program Distant Suns as  being  a  good
computerized star chart, that was written by Mike Smithwick, who some-
times reads this group.  If  Mike  would  care  to  contact  me,  I'll
include price and address here.  If he wants to send me a review copy,
I'll even give my opinion.

11.1.1.  What Programs Can I Get For Free?

Well, I use a program called ephem, for calculating  a  whole  lot  of
stuff (like ephemerides, phase (of moon and planets), dawn, dusk, etc.
and like it a lot.  There is a motif based upgrade,  xephem,  which  I
have not yet used.  You can pick it up from ftp.x.org or iraf.noao.edu
in contrib/xephem.  Ephem and xephem were written by Elwood Downey.

I have heard good reports  about  a  program  called  'starchart'  and
another  called  'observe', the former prints out star charts, and the
latter calculates where objects are, in a format  accepted  by  'star-
chart.'  You  definitely  want to get these before paying for anything
else.

For Macintoshen there is a free/shareware program  MacAstro  available
>from      cs.dal.ca    in    /pub/comp.archives/macastro    and    from
aix370.rrz.uni-koeln.de                                             in
/.disk2/usenet/comp.archives/sci/astro/macastro.  It will show the sky
at any time, including stars, sun, moon and  planets.   It  will  also
give  the  rising/setting  times  of  the  sun  and  the  moon.  It is
shareware, $20, written by Nicolas Mercouroff (nm@cs.brandeis.edu).


12.  About this FAQ

This FAQ is a copyright work.  You have my permission to reproduce  it
however  you  like,  as long as you don't make any money off of it and
you leave all the attributions and the copyright notices.

All the opinions are mine, and not my employer's.

If you have any questions, I will be happy to try to answer them.  But
be warned that I am not a very experienced observer.  Many many people
on the net have much much more experience than I do.

Because the FAQ is kept as an nroff file, generating diffs is  a  hard
problem.

This FAQ does not appear on news.answers, because they didn't like the
format.

No, I am not interested in having someone convert this to HTML  for  a
Mosaic  World  Wide  Web  Information Superhighway Wired Magazine type
application.  This is an  article,  and  I  want  people  to  read  it
through.

This FAQ is available via anonymous FTP from ftp.cisco.com,  in  /faq.
The  files are astro1.txt and astro2.txt for printable text; astro1.ps
and astro2.ps for postscript files.
 

To the first FAQ

 

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