vs. Build it Yourself
you're just getting started
astronomy as a
best to purchase a telescope rather than trying to build one.
There are a lot of very good beginner level telescopes that
can start using right out of the box, many with
The most important advice I can give is to stay away from
department store telescopes, usually packaged in boxes covered with
claims of high magnifications and fantastic pictures of planets,
galaxies, and nebula. These telescopes become more trouble
they are worth and will quickly destroy any interest in
astronomy; remember that you ultimately get what you pay for. Take
look at Celestron,
Telescopes, and what you
can find on the www.
There's always a good
selection of name brand telescopes
for sale on eBay.
and Mount Types
webpage section gives a
very short introduction
telescopes and telescope mounts. I have several
webpages (tutorials written at the beginner level) that give
a discussion of
the major telescope types (Telescopes
and Optics Tutorial), explain
how celestial objects move (Celestial
Motion Tutorial) and introduce
the different types of
telescope mounts and how they track celestial objects (Telescope
telescope building experience is limited to Newtonian
which are simple and easy to build.
With regard to
telescope size, this is one area where size really does count.
Large mirrors collect more light and will allow you to see more
details, but there are two catches: cost and portability.
mirrors are like diamonds, a doubling in size translates into
considerably more than double the price. Also take into consideration
that bigger mirrors cause you to sacrifice some degree of portability
and ease of set-up. With all that said, my advice is to purchase as
large a mirror as you can. When I purchased my optics in 1981, a 10"
mirror was considered a large telescope. The current trend in
telescope construction is toward much larger aperture
making my telescope now a large-medium telescope (however I'm still
quite satisfied with its performance). I would not recommend anything
less than an 8" diameter mirror (about $50-60 on eBay).
There are many different
types of telescope mounts, each with
advantages and disadvantages. A detailed description of telescope
mounts can be found on the Telescope
Mounts Tutorial. The
remainder of this
section gives a very brief introduction to the most common types of
telescope mounts: Altitude-Azimuth
(Alt-Az) and Dobsonian
If you only want a telescope
then an Alt-Az
(old fashioned up and down type mount) is
all you need (below diagram, left image). The best all round Alt-Az
design has to be a Dobsonian type
mount (below diagram, right image). This is what I originally
constructed in my first
building project and is what I recommend to a first time builder. A
Dobsonian mount is simply a 3 sided plywood box (pink) that
rotates on some type of Dobsonian
(usually Teflon sliding against metal or plastic). The telescope tube
the telescope box (light blue), which rests on top of the 3 sided box.
simple to build, very rugged, can take a lot of abuse, are
extremely stabile, and can even be converted to a GoTo system.
you want to eventually try
astrophotography, then you probably want
type mount (one axis
points parallel to the
pole). This allows you to move the telescope and camera counter to the
Earth's rotation for long exposure imaging. Another option is
that an Alt-Az
telescope that can be placed on a wedge
plane) so that one
axis is tilted to be parallel with the Earth's polar
axis. More information about these types of telescope mounts
can be found on my Telescope
first thing I would
recommend is to just spend some time
on the www looking at what other telescope builders have constructed. I
would ultimately recommend you construct a Dobsonian
style telescope or
some variation on this theme. Stellafane.org's
a Dobsonian Telescope pages give
all the necessary planning
and step-by-step instructions to build a Dobsonian telescope.
single best article I've read on telescope building was a 3 part
article in Astronomy
(June-August, 1980) by Bob Kestner and Richard Berry, titled "How to
Dobsonian Telescope". If you can get a reprint of this
article, just follow the instructions.
The last overall design
is the most important: Keep It Simple (KIS).
My experience as an engineer is that the
simpler a thing is, the better it functions- there's just less to go
This remainder of this section lists some things to think
about while designing your telescope and looking at designs on
It Simple (KIS)
this be permanently setup in a fixed
location or do I
need to build something that I can transport to a remote
I transport it assembled or does it need to
down for transport?
to a scale that you can move and assemble
transport or my storage location dictate
that very long focal
length telescopes may require
stand on a ladder to reach the eyepiece.
a system that's fast and easy to set up
(in the dark)
some details to make things easier:
eyepiece holders, etc.
the system so it's easy to modify without
requiring a complete rebuild.
with adjustable features
doesn't violate KIS).
design philosophy of keeping
everything as simple as
possible was also out of necessity. I live in a rural area,
hardware stores carry only basic items. As a result,
most of the items I use can be purchased at a local hardware
or home center. If
you have a local hardware store and
access to the www,
then you have
access to everything you will need.
have no special construction
skills other than
basic carpentry skills. My workshop is also very basic: hand
tools, a telescoping miter saw, a router, drill press, and a couple of
power hand tools. A basic collection of hand tools and the ability to
measure, cut, drill, and tighten a bolt is about all you
need. Following are a few additional tools that will
really help your construction, but you can probably get by without
router with a circle cutting attachment-this
is the best
way to cut circular sectors
drill hole cutting set
tap and dye set to thread metal rods and holes
good all purpose file for metal and wood