If you are interested in buying a telescope,
research before you buy.
RCA Members can
borrow a scope from the Library
A rule of thumb: if a telescope makes claims about having "450 power!"
(450X) or more, don't buy it. There are lots of cheap
instruments readily available on the market -- in local department stores
or local discount stores -- that do not perform very well for astronomical
use. If a telescope costs less than $300, it falls within this category
and should be avoided at all costs. In fact, a decent pair of binoculars
in the $150-200 range will give you much more viewing pleasure and fewer
headaches than these mass-produced thingamabobs.
There are several articles and booklets in
the RCA Member Library that provide information on choosing a telescope
and appropriate accessories. Also, talk to other club members. The variety
of instruments RCA members have range from binoculars to large reflectors,
from refractors to Schmidt-Cassegrains. Each instrument has its advantages
and disadvantages, so it is important that you determine your
needs in order to match them up with the equipment that fits them the
closest. The time, money, and headaches this research can save you are
These are perhaps the most overlooked type
of "telescope". A good pair of binoculars is a cost-effective way of
introducing yourself to the night sky. They are especially useful in light
polluted areas such as suburban or city locations. Many books have been
written detailing the different types of objects easily viewed by most
binoculars. In fact, over 50 of the Messier objects can be viewed with a
pair of 10x50 binoculars. To be effective, binoculars should be at least
7x50, with 10x50 being a good starting pair. The "7" and "10" refer to
power while the "50" refers to the diameter (in millimeters) of the lens.
Binoculars with a diameter of less than 50 are not suitable for astronomy
because they simply cannot gather enough light to be effective.
Also called "Newtonian telescopes", these
are by far the most common telescope today and are excellent entry level
as well as advanced telescopes. A common and very popular telescope of
this type is also called a Dobsonian, which refers to a Newtonian or
reflecting telescope on a low-tech mount developed by a famous amateur
astronomer named John Dobson, hence The Dobsonian.
Reflecting telescopes are
characterized by a long tube with a mirror at the bottom end and the
eyepiece at the top. Small telescopes start out with a mirror diameter of
4.5 inches and go all the way up to 40 inches in diameter. A good starting
telescope has a 8" diameter mirror and will give countless hours of
enjoyment viewing the night sky. While smaller diameters will still allow
you to view many of the same objects, an 8" or larger telescope will give
you much more detail. These type of telescopes are manual in nature, with
the operator having to physically move the telescope to point at an
object. Unless the scope is mounted on an equatorial mount, this type of
scope is not able to "track" a star so that it stays within the field of
view at all times. An 8" Dob costs around $400-500, but an 8” reflecting
telescope mounted on an equatorial mount can run as high as $1,000. The
major benefits of these scopes is that they are easy to set up and operate
and you get more aperture for the money. The biggest disadvantage is that
they take up more room to transport so aren’t as portable in the larger
sizes as other types of scope.
Commonly referred to as SCTs, these
telescopes are "stubby" versions of the reflecting telescopes in that they
fold the light twice from the time it hits the main mirror to the time the
light exits at the eyepiece.
They are normally mounted on either
fork-mounts or German equatorial mounts, which allow the telescope to be
oriented in such a way that it is in the same "plane" as the night sky.
These types of telescopes are normally equipped with a clock drive, giving
the ability to track an object for hours at a time. Their advantages are
that they are also capable of doing long-exposure photography and they are
more portable than their Dobsonian counterparts for sizes greater than 8"
in diameter. It is important to note, however, that they offer no better
viewing than the same size Dobsonian telescopes. They just come with more
bells and whistles. An 8" SCT costs between $1,200 and $3,000, depending
on the sophistication of the computer and tracking hardware.
Refractors are your "typical" telescopes in that this is what most people
picture when thinking of a telescope. These use lenses to refract and
focus the light instead of mirrors which are used by both Dobs and SCTs.
Refractors will give sharper views than
their SCT or Dob counterparts at smaller sizes, making them more valuable
for planetary viewing where crisp detail is more important. They can be
mounted on German equatorial mounts (allowing the telescope to track
stars) or alt-azimuth mounts. An entry level 4" refractor without
tracking hardware will cost around $1,000, but can go upwards of $2,000 to
$3,000 depending upon the quality of the lenses, mount, and tracking
are not to scale. Dotted lines represent the path of light from when it
enters the scope to where it exits at the eyepiece.