Below are some basic techniques that experienced
observers use all the time to enhance their viewing. Many beginners are
disappointed that they cannot see some of the details described in books or by
other advanced observers. All that is needed is to use the right methods
of observing to see much more. Employ these little tricks to get the most
out of your stargazing.
Use Averted Vision
This technique alone will allow you to see easily
twice as much detail when stargazing. The human eye contains two sets of
light-sensitive cells: the cones which see color and the
rods which see
black and white. While sensitive to color, the cones are very insensitive
at low light levels. (This is why you don't see color in faint objects
through a telescope, but bright objects like planets still show color.)
The rods take over at night because they have greater dim-light sensitivity.
But the cones are located in the center of the eye, and the rods are mostly
located around the periphery. This means looking directly at a celestial
object uses the insensitive cones, but looking off to the side of the object
puts the light from the object right onto the rods. New observers are
surprised how much detail pops out when using averted vision. Objects
otherwise invisible suddenly are seen, and faint details like spiral arms in a
galaxy or faint stars around the edge of a globular cluster become visible.
Once you start using averted vision it will become perfectly natural and you
will begin doing it without even thinking about it.
Get Dark Adapted
Not only is it important to have dark skies for
observing, it is critical to be dark adapted. If you've ever gone for a
hike under the full moon you know how much it is possible to see with faint
light. The moon gives off a half million times less light than the sun, showing
that the human eye has a huge dynamic range, allowing you to see in all
conditions. But the change from seeing in bright light to dim light does
not happen instantly. In addition to rapid changes like the pupils opening
up, chemical changes begin to occur allowing you to see at lower light levels.
These chemical changes take from fifteen to thirty minutes to take full effect.
After walking outside to observe or after using a flashlight for setting up the
telescope, give yourself some time to adjust to the dark before expecting the
best views. Also, take care to preserve your night vision once you are
adapted so you don't have to start over again. Use a red flashlight for
reading star charts. The human eye is least sensitive to red light so this
type of flashlight will not be as likely to ruin your dark adaptation.
Eliminate Stray Light
This might seem obvious, but local light sources
like your neighbor's motion sensor lights going off every time his dog goes out
can ruin your night vision. As well, bright nearby lights can shine into
the telescope and reflect off optical surfaces to reduce contrast. When setting up the telescope,
consider where light sources will be and try to block them as best as possible
by setting up where a wall or fence will be between your scope and the light
source. A dew shield works well to keep light out of the
telescope tube. Inviting neighbors over to view through the scope usually
works well for getting them to turn off lights at night. Diplomacy always
works better than firing a slingshot at their light bulbs. Some observers
go as far as setting up panels to block stray light sources. Of course,
the best solution is to drive out away from the city entirely, but on nights
when you have to stay home to observe, do what you can to keep stray light under
A shaky telescope can ruin an otherwise good
observing session. The obvious place to start stabilizing a telescope is
its tripod. A good telescope should already have a pretty stout tripod,
but occasionally scopes are under-mounted. If this is the case, a great
Vibration Suppression Pads, such as those made by Celestron.
These pads are about the size of hockey pucks and contain a material known as Sorbothane. Originally used to dampen vibration in turntables, Sorbothane
has an almost magical ability to reduce vibration in telescopes. The pads
are placed under the tripod legs and shaking is reduced significantly.
Vibration reduction pads have to be seen to be believed. If vibration is
an issue, this is a great solution.
In addition to minimizing existing vibration, try
to avoid setting up the telescope in a place that might induce vibration.
A popular place to set up a telescope is on a flat rooftop, but this is a
notoriously unstable position. Since rooftop areas are often not supported
in the center, they have a tendency to flex as someone walks around. If
you are observing alone, this might not be a problem, but when sharing the view,
expect some shakiness as people move about. While a rooftop location may
get you away from trees and other houses, unless there is no other option try to
avoid setting up there. See the next section for another reason rooftops
are less than ideal observing locations. Similar to a rooftop, wooden
decks are often unstable. Your best bet is to set up on stable, solid
ground whenever you can.
The steadiness of the atmosphere--known as
conditions--is critically important to observation, especially of the planets.
While there is little you can do to control inherent atmospheric turbulence
caused by wind or cold fronts or the jet stream, you can try to avoid local
conditions that give rise to choppy air. In the wintertime, houses and
other building often vent warm air which causes turbulence. Try to avoid
looking low over buildings, especially around chimneys or vents. Likewise,
dark rooftops hold in heat during the day and release it again after dark.
This is another reason not to setup on a flat rooftop, as the heat radiating off
it can distort the views through the telescope. Cold air pools into
low-lying areas, often causing turbulence. Streams and desert washes tend
to produce poor seeing conditions in cold months for this reason. One of
the worst places to be in cold weather is at the bottom of a mountain range.
Cold air will sink down the faces of the peaks and roll across the valley or
pool into basins, producing awful seeing. This is one of many reasons
observatories are built at the tops of mountains. But even mountains
themselves generate bad seeing sometimes, as they chop up airflow.
Isolated peaks tend to have better seeing than peaks in the middle of larger
ranges. These are all things to consider when selecting an observing
sight, especially for high-resolution viewing or imaging.
Use the Correct Magnification
There are two common magnification myths in
astronomy. The first is that more magnification is better. The
assumption of many beginners is that to see things farther away you need more
power. But the trick isn't seeing farther, it's seeing fainter. And
for this, aperture is the key more than magnification. In fact, lower
power produces a brighter image and almost always produces a better view than
high power. However, this leads to the second myth, an assumption made by
more experienced stargazers: that lower power is always better. The truth is,
there is an ideal magnification depending on the telescope used, the object
being viewed, and the observer's visual acuity. In general, a medium
magnification produces the best view.
Low power is great for finding objects and for viewing
very large objects such as the Pleiades or Andromeda Galaxy. High
magnification can be good for small targets like planets or double stars,
but most observers quickly learn that there is definitely such a thing as too
much magnification. For most deep-sky objects, though, medium power is
ideal for bringing out the most detail. We'll spare you the details here,
but suffice to say that it has to do primarily with the resolving power of the
human eye. (See the Observing Theory
page for all the gory details.) In general, use the following guidelines
4x per inch of aperture
12x per inch of aperture
30x per inch of aperture
For example, using an 8" telescope, the minimum
magnification would be around 32x, the best resolution for deep sky objects
would occur at around 96x, and the highest useable magnification would be around
Use the Right Filters
Filters can be used to bring out a great amount of
detail when used properly. By far the best filter to have is a
polarizing filter. A polarizing
filter works by cutting down the amount of light coming through the telescope
and is adjustable to vary the amount of light transmission. Nothing works
better on the moon and planets to enhance detail. The moon in particular
can be so bright that it is difficult to look at, especially with a larger
telescope. Planetary detail is subtle and can easily be lost in the glare
of a bright planet like Jupiter or Mars. Using a filter to cut down on the
brightness of the planet will allow much more detail to show through.
The next best filter to use is a narrowband
nebula filter. Nebula filters work by
blocking out light pollution but transmitting the light given off by
They only work on nebulas and not galaxies or
clusters, but they are worth their
weight in gold for improving detail. These filters work best when the
observer is dark adapted, so be sure to give yourself ample time to adjust to
the darkness before using one.
Take Your Time
This technique probably cannot be overstated.
Remember, what we're doing with telescopes is called observation for a reason.
Take your time and really observe an object. Spending even 2-3 minutes
studying a field of view will reveal vastly more detail than simply glancing at
an object then hurrying on to the next. Stephen James O'Meara has written
great observing guides to the Messier objects and Caldwell objects, and his
drawings of these celestial subjects show a wealth of detail. People often
are amazed at how much detail O'Meara can see with a small telescope.
While he might be gifted with unusual visual acuity, what really makes him a
world class observer is the fact that he really takes time to study the objects.
Says O'Meara is his first guide: "For most of the Messier objects, I observed
each for an average of six or more hours over three nights. Some of the
more complex objects were observed for three hours per night for several nights.
Don't expect to see all the detail in my drawings with just a glance.
Challenge yourself to spend the time to really study these objects... ." A quick glance at Saturn shows it rings; a long look reveals divisions in the
rings, cloud bands, subtle colorations, and moons. No technique on this
list will show you more than spending time examining an object in detail.
Have a Seat
This trick goes hand in hand with taking your time
observing. You will see more if you sit while viewing. For one, this
allows you more time to relax and examine the field of view. Your body is
not concentrating on balancing in the dark and the muscle strain of standing up
and bending over. Relaxing while viewing lets you mind concentrate more on
the view. There is also a tendency to move around a bit while standing and
observing, so sitting helps to stabilize the view. There's no sense in
setting up a rock-solid tripod on stable ground just to have your body wobble about in the dark
and blur the image in the eyepiece. Take the strain off your body so your
brain can fully enjoy the wonders of the heavens.
Observing with a Telescope