Stargazing with Binoculars and Telescope
Cosmology 101 Items',
Planets and the moon are almost always an attraction for beginning
stargazers. But astronomy holds a lot for the amateur astronomer. While
planetary observing requires primarily long focus optics, good seeing, and high
magnification, star observing is more varied. Some types of star observing
require the same considerations as planetary work, but other types of observing
require different considerations.
To get started in stargazing, you need a map, like the star map for tonight
shown above, but perhaps larger. This one was obtained from the Xephem planetarium program,
a great tool for any stargazer. But there are other tools, like the Kstars planetarium program, and
perhaps the even more popular Stellarium planetarium
program. There's also NightWatch:
A Practical Guide to Viewing the Universe, chock full of information and diagrams to get you
Then you need some optics. Not a lot to get started really, but at least a
pair of binoculars, say a 7x50 pair. That means a pair with magnification of 7
times and lens diameter of 50mm. It's tempting to get bigger, but hand-holding
a pair of binoculars that magnify over 10 times is daunting at best, and bigger
binoculars get heavy faster than you can realize. You can put your binoculars
on a tripod and see better, with much less fatigue, as shown on the Binoculars Tutorial
You can also get started in stargazing with a small telescope, it doesn't
have to be a big one. Something like a 60mm Refractor is a good choice. With such a telescope,
you get something that sets up easily, thermally stabilizes quickly, and
requires very little maintenance. Yet many double stars and star clusters
are with easy reach of such a telescope.
A lot of stargazers start with, and continue to view (I do) the many
items in the popular star catalogs, shown in summary at Star Catalog Data. I was working to get familiar with Google Sheets, and created the Star Data sheet
to illustrate the pivot table function.
|Messier Type||Number||Average Mag
The Star Catalog data has pivot table summary sheets for each of three
popular star lists, available through the tabs at the top of the
spreadsheet. The summary table of the Messier list is shown above. As you
can see if you examine it, there are a couple dozen open clusters available
that are visible in even small telescopes, and over 100 when all three lists
of the Star Catalog summary sheets are considered. The summary tables on
the Star Catalog Data spreadsheet also reveal that among object types, the
open clusters are among the brightest objects, again making them ideal for
binocular and small telescope astronomers.
Also available for the Messier catalog is a nice collection of public
domain images at The Two Micron All Sky Survey at IPAC. A quick look at these
images will help you recognize the items when you run across them. You'll
recognize the globular clusters when you see them, and most open clusters.
But a few, like Messier 29, may escape notice if you aren't familiar with
Incidentally, if you want to use one of the quickest ways to locate targets
from any of the three lists in the spreadsheet, I highly recommend that you
try out the Star
Pointer utility. If you have setting circles on your telescope mount, or are
willing to make some, star pointer tells you where to point your telescope to
locate any object. It works with altazimuth or equatorial mounts, and will save
your location data in a cookie for quicker use next time, if you allow it. See
the About Star
Pointer web page for details.
If you want to try making some setting circles for your telescope mount, you
can download the Setting Circle
Template to assist you in making your own setting circles. Just adjust the
diagram's size with a computer program, or with a copy machine, glue it onto a
thin piece of metal or wood, Then mount it to your particular telescope mount.
That's what I did for both axes of my tripod, shown in the above image of my Pipe Fitting Tripod.
The Practical Side Of Stargazing
It turns out, rather than for just their beauty, amateur astronomers have
another good reason to stargaze. Looking at a single star image under high
magnification can help you qualitatively test and align your telescope optics,
whether you use your telescope for planetary work, star observing, or both.
If you are using star testing to examine or align your telescope, you need
good seeing, optics that are cooled down, and high magnification.
Observing moderately bright stars under good seeing with high magnification
can tell you a lot about the quality and alignment of your telescope. You can,
for example, identify an over corrected or under corrected objective, spherical
aberration, turned down edge (for mirrors), and astigmatism errors just by
examining out of focus star images. In fact, if you don't own a laser
alignment tool, observing a star at high magnification is a good way to tweak
up your instrument's alignment.
Star testing is done by examining a magnified star image with the eyepiece
racked both inside and outside of focus, and comparing the resulting
If you are using a star test to align your optics, you're making using of
the natural diffraction image (illustrated above) that appears in a de-focused
star target. You might find the star alignment procedure difficult with a
telescope that doesn't have a clock drive. By the time you go to the business
end of your telescope to make an adjustment and return to the eyepiece, the
star may not even still be in your field of view. If you live in the northern
hemisphere, you can resolve this issue by using Polaris as your alignment
A good website that shows the kind of star images produced by different
optics errors is Star Testing Astronomical Telescopes.
Star aligning is a technique I've used a lot. It is sometimes a touchy
procedure, however. Often I either bump my telescope or make too big an
adjustment and cause the star to be moved out of the field of view. If you want
a quicker and easier alignment method, you probably want an alignment tool.
You can read up on how to align or collimate Newtonian reflector optics
at the Collimation Tutorial web page.
Double Star Observing
Aside from the large number of open clusters easily available to small
telescope users, another type of star work within reach is double star
What are double stars?
Double stars are star pairs (sometimes even more multiples than pairs)
where the component stars are so close together that to the naked eye they
appear as a single star. They may be so close that they even appear to be
a single star with a small telescope.
The stars may be locked together gravitationally, or they may be actually
very far apart and independent and just happen to be along the same line of
Double star observing is fun for a number of reasons. I use double stars (or
binary stars as they are sometimes called) primarily to compare and evaluate
optics. I get my best double star views with a long refractor, like the Celestron
AstroMaster 70 EQ Refractor Telescope. Particularly I use my Long Focus 60mm
telescope. I have bigger telescopes of reflector design that can, on good
nights, resolve closer doubles, but nothing seems to deliver the text book
double star images like a long focus refractor.
Observing close doubles under good conditions gives some indication of
optical quality. If a double separation is just over the theoretical resolution
of your telescope and can be cleanly split, your telescope's optics are near
perfect. If not, maybe doing some star testing can help identify the
problem. Also, if you have trouble separating doubles around the resolution
limit of your telescope, don't despair. Rather just enjoy the view. It could
be that seeing conditions just aren't good enough at the time of your
optics test. The double components may be too dissimilar to make the
difficult separation easy.
Doubles are also interesting objects to observe because of the variability.
Often the component stars are different colors, or different magnitudes. These
variations give each double its own identity. The following table presents
just a handful of double stars, but ones I find enjoyable. They all have
components that are separated by 2 arc-seconds or more, and have magnitudes
within reach of a 60mm telescope. Each star name is a link that will bring
up a small constellation map with a reticule symbol over the location of the
Star Cluster, Galaxy, and Nebulae
For more general star, galaxy, and nebula observing, seeing is not
much of a concern, but transparency is. You'll be straining to see the
faintest details of interesting objects, and nearly every photon matters.
It's with this general star observing that aperture is of great importance.
The bigger the aperture of the telescope you use, the brighter objects will be,
and the more objects you will ultimately be able to see. However, if you get
such a big telescope that it becomes too much of a bother to use, you've gone
I use my 60mm telescope for some star cluster and nebulae observing, but
more often I use my 6
Inch Newtonian, which is basically the same as the Celestron
Omni XLT - 150. For me the short focus Newtonian is great for these
objects, being of significant aperture, but easy to set up because of it's
stubby design. I know of others who have a lot of fun with an even more
portable reflector telescope, the
Orion 10015 StarBlast 4.5 Astro Reflector Telescope (Teal)
, a very compact and popular design for star
You can check out the Telescope Tutorial for
more details on how optical performance relates to aperture. For here I'll just
mention that detail resolution is proportional to the diameter of a telescope,
and limited by atmospheric phenomenon, as shown at left. Light gathering power,
all important for star observing, is proportional to telescope diameter
squared. So for star observing, diameter is especially important.
Again I refer you to the Messier summary table shown before. There you'll
see the number of each type of object, and you'll see that while the average
magnitude of the open clusters in the Messier list is 5.77, the average
magnitude of spherical galaxies in the list is 8.89 -- much dimmer. So galaxy
hunters go for big aperture, 6 inch and above. Some very experienced observers
can see most of the Messier list galaxies with a 60mm refractor, but they
observe from dark sites, and know all of the optimization tricks.
Star Observing Hints
Most star observing is done at relatively low power. Open clusters, the
Andromeda galaxy, and some nebulae are large enough in apparent size that low
power (less than 100x) is best. For such observing, a clock drive isn't
Planetary nebulae, globular clusters, and some galaxies will generally
work best at moderate power, perhaps 100x to 150x. But even at this
magnification, a clock drive isn't a necessity.
Transparency is usually best when objects are well above the horizon.
While not as critical as with planetary observing, a cooled down telescope
will help you get better views.
If you live in a large city, you may need to find an observing site that has
better transparency. Another constraint caused by cities is all the lights.
While not strictly affecting transparency, stray light definitely restricts the
ability to see dim objects. A different location may provide darker skies.
Let your eyes become fully dark adjusted for observing stars. You'll be
surprised how much more detail you can see with fully dark-adapted eyes.
You may be one of those observers adept at the star-hopping technique
of locating targets. If you are using charts between observations, use a red
light to observe your charts. Eyes are less affected by red light, and you'll
loose less of your night vision if you use a red beam. If you use a computer
screen for star charts, see if it has a night vision mode, which will again
display primarily with red light on a black background.
If you're not an effective star-hopper and happen to have setting circles on
your telescope (Altazimuth or Equatorial), then I again urge you to check out
the Star Pointer
web page for a handy way to find targets. Star Pointer generates a table of
visible star objects for your location which is updated about every 30 seconds
to give you accurate coordinates for each target in the table. Tables can be
generated for any one of a number of popular star target lists, such as the
Messier, Caldwell, and Herschel 400. Check it out. It's even handy if you
happen to have a computer guided telescope, in that it presents at a glance the
targets that are currently visible.
If you have a pesky street light or porch light that's giving trouble,
consider using a towel or your coat to drape over your head when at the
eyepiece. This will block out the troublesome stray light. If your
telescope is portable, you may be able to move it to a position where
your house, garage, or a shed can block a pesky streetlight or porch light.
You might consider using a nebulae filter, like the Solomark 1.25-inch Narrowband 10nm Oxygen-iii Nebula Eyepiece Filter.
These filters work by screening out wavelengths that interfere with seeing
nebula features. Keep in mind, however, that since these filters screen out
light, they don't work as well on smaller aperture telescopes. I don't think
the investment is worth it if your telescope is smaller than an 8 inch.
For very dim objects, learn to use averted vision to help discern
faint details. Averted vision describes the technique of looking away
from the dim details you want to see, and examining them as best you can
with your peripheral vision. The center of your vision is best for details,
but your peripheral vision is more light sensitive. Experiment to find
which way to avert your vision to find the most light sensitive portion
of your eye.
What Telescopes are Best for Stargazing?
If you are new to amateur astronomy-- start with a decent pair of
binoculars. You can get a good functional pair like the
Celestron SkyMaster Giant 15x70 Binoculars with Tripod Adapter
for under $100. Try for 50mm
diameter or better. And don't get too high a magnification. You'll find you
can't hold them still well enough over about 10x unless you mount them on some
kind of tripod. I generally use my Barska 70mm Binoculars, which are basically the same as the aforementioned Celestron SkyMasters. Check out the Binocular Tutorial
page for more information.
You may find you can get by for some time with a couple of pair of
binoculars, like a 7x50 for spotting objects and a 10x50 or 15x70 for a bit
higher magnification. Or you can spend a bit more and get a zoom binocular.
As to telescope type, there are a couple of considerations. Dobsonian
telescopes can certainly give the most aperture for the dollar. An 8 inch
Dobsonian, like the
Orion 8945 SkyQuest XT8 Classic Dobsonian Telescope
, can go for under $500, while an 8 inch Cassegrain
will generally cost $1500 and up.
Of my telescopes, I use most the 6 Inch Newtonian,
which has the largest aperture of my instruments. Next used, for it's
convenience, is my 60mm Carton
Refractor. It can't bring in some of the dimmer targets like my 6 inch, but
shows superlative star images, and is exceedingly easy to use. Third on my list
Celestron NexStar 5 SE Telescope
, which is handy for locating the many hard to find
objects. The computerized mount takes me right to targets I often can't easily
find any other way.
While more aperture will let you see more stars, aperture isn't the only
thing you want to think about. As a beginner, you may want to consider a
compromise between aperture and ease of use. You can purchase 5 inch or so
Newtonian reflectors or 3.5 to 8 inch Cassegrains with computerized clock drives. These
units are more portable, and the computerized clock drives and extensive
star catalogs let the telescopes locate objects for you.
That being said, I point out that there are two kind of popular Cassegrain
telescopes available for the beginner astronomer. See the Cassegrain Tutorial
for more details. Suffice to say, I would argue that for stargazing, a
Newtonian or Schmidt Cassegrain would be better than a Maksutov. The Maksutov
has a very large f ratio (around f/15), which provides too narrow a field of
view for some star objects.
Purists will argue that you should learn the constellations, and then learn
how to star hop to find objects with your telescope. Others will say it
wastes too much time, and computerized mount telescopes allow you to see many
more objects in an evening.
I think it all depends upon the observer and how he or she enjoys the hobby.
You may find that the ability to see several objects in an evening because of
the telescope's computerized drive is more important than a large aperture.
You may also find that portability plays an important part to you. If you
are a youngster, elderly, or handicapped, you may find that the difficulty of
working with a large telescope out weighs its benefits. You may find that for
good views you have to travel to a different site. For these and other
reasons, you may want to temper the urge to get a behemoth telescope. I've
been involved with astronomy for over 40 years, and I currently own nothing
bigger than a 6 inch Newtonian.
You might want to take time and consider which telescope design matches up
to your anticipated observing. For finding deep space objects such as galaxies,
you'll likely want to concentrate on the wide-field and general purpose
telescopes, the larger aperture the better.
For small objects like globular clusters and double stars, you'd likely be
best served by telescopes of longer focal length, such as a refractor,
Cassegrain, or Maksutov. Again, the larger instruments will let you see dimmer
Star photography, as with star observing, is quite varied in technique.
Constellations, rich star fields, and some extensive nebulae can be
photographed with simply a guided camera. You can use either the barn door
mount or the piggyback method. See the Observing
Comets for descriptions of those types of photography. I've taken
a few star object pictures using my Piggyback Camera Mount
For photos of clusters, globular clusters, and galaxies you'll need to
photograph through your telescope. This is a most difficult kind of photography.
To do it you need a clock driven telescope and either an auto-guider or
a guide scope mounted along side your main instrument.
Time exposures are a must here, typically several minutes. While this
kind of work can still be done with a standard film camera, if you have the
money you may want to buy a specially designed CCD camera for telescope
Use this astro-customized search engine to find astrophotography cameras