ALCOVE Database ®
Building My 8" Newtonian Reflector
"And finally, there is understandably the stimulus of being
able to unlock the mysteries of the heavens by a tool fashioned by one's own
Russell W. Porter, March 1923 - founder of
In the Beginning ...
... there was only a dream, and the dream was mine, and the
dream was about having a large telescope...
It all started when my friends living a couple of blocks away
(in Istanbul, Turkey) had considered building a telescope of
their own. Several times a month, we were getting together to
discuss different techniques of telescope making, its
difficulties, obstacles we can encounter and possible solutions
we could think of. Finally the decision was made. Due to lack of
necessary equipment, knowledge and material (carborondum, pitch
lap, etc.) we eliminated the option to make mirrors by ourselves.
Then we moved on with the second option: buying out ready-made
commercial mirrors from abroad.
Whilst my friends got a 10" parabolic mirror from Broadhurst, Clarkson and
Fuller in London, UK; thanks to the financial help of
my father A. Fuat Menali, I ordered an 8" parabolic mirror
and a corresponding diagonal from Meade
Instruments Corp. in California together with a 9mm
Orthoscopic eyepiece and a 3X barlow lens in March 1984.
As soon as the small package arrived via Switzerland (to avoid
exorbitant Turkish customs duties) in May 1984, I started working
on the plans of my future dream telescope. I carefully measured
the focal length and draw detailed schematics on millimetric
paper. I had found a very useful resource at the library of the Bogazici University where I was attending to
the Business School:
"Telescopes: How to Make Them and Use Them”, Vol 4,
Sky and Telescope The Macmillan Library of Astronomy, published in 1966.
Also, I happened to have a xerox copy of the
first French edition of Jean Texeraux's "How to Make a Telescope".
These two books helped me to understand basics of telescope
design and construction. Additionally I went through hundreds of
pages in both Sky and Telescope
and Astronomy magazines at
the university library to check almost every article published on
telescope making (I subscribed to both in 1985, after I jumped
into the ATM effort).
The people who know me closely are aware that before embarking
on any challenging project in my life, I like to analyze it in
depth and plan thoroughly ahead. In a couple of weeks my
telescope was ready, of course only on the drawing paper! I even
constructed a small scale replica from cardboard. Now was the
time to tackle the real task: building an 8" reflecting
newtonian telescope! With a very important problem at hand ...
At the very start of my endeavor I had a very challenging
problem: in Turkey none of the telescope accessories was readily
available in the market. Not only it was due to lack of even a
single astronomical instrument component manufacturer available in the
country (things got started improving in April 2006 after my friends and I
ATM Turk, a
discussion list over the internet for Turkish speaking ATMs), nor there was any
company importing them as well (please check out our Turkish
Astronomical Links page for current vendors in Turkey). So
what did I have to do?
I had to improvise and find a way out how to build each one of
these components. As I did not have any tools nor any experience
in using such tools, I had to seek for professional help. As a
result, I decided to go to different workshops where I can ask
for a specific component to be built. So I did ...
I had decided that I should use a lightweight material for the
tube so that it could be easily handled and transported. Among
the options I considered were either building a tube from
cardboard ("Sonotube" or similar) or using thin
aluminum pipe (similar to my 50mm refractor) of large aperture (9
inch or so). However I gave up the idea of using these materials
as they were either not strong enough or too heavy. Then it came
to my mind that I was very well aware of such a material which
was really tough, yet considerably lighter than any other that
might be used in telescope making: fiberglass!
The only places where I could find somebody to help me to
build one were either containment tank (for fluids) constructors
or auto body workshops. I chose the latter as an industrial park
full of auto body shops was conveniently located near my
neighborhood. The rest was relatively easy. I chose one such
workshop and explained the guy, who never knew what a telescope
was in his entire life, what purpose I would use the tube for. To
my utter astonishment, he came up with a very clever idea of using
a steel mold which had the shape of half a cylinder. He cast the
first half of the tube in the cylinder, then the second half was
cast and both halves glued together with sheets of fiberglass. Update
as of April 2006: I went to the shop of the same guy in April 2006
when my wife Gamze and I were in Turkey to watch the total solar eclipse from
near Side on the Mediaterranean coast. He helped me to install on the tube a 2"
second-hand focuser that I had bought at
NEAF a year earlier. I
also remembered what his name was: Ahmet Erturk. He instantly recognized
me, and the tube he put together, more than 20 years ago!
In a couple of days my telescope tube was ready! And it was
weighting less than 6 pounds so that I was carrying it with just
one hand! Wasn't that unbelievable? I had started building my
dream scope at last!
In order to reduce internal reflections I used flat black
paint for the interior of the tube. Although I worked inside out
applying the paint with a brush, you should have seen me after I
had finished the work! I can just say that I could not wear the
same T-shirt again! For the exterior color I chose glossy white
to be sprayed at an auto body shop. I preferred white color just
for aesthetic reasons even though it is not recommended as it
takes longer for a white tube to cool down to ambient
temperature. A minor nuisance for me! I wanted to see stars, not to build a
I had to find another workshop to have the mirror cell built
from iron. The cell consisted of two concentric rings (1).
The outer ring of the cell fitted outside of the tube which it
was attached to with bolts and nuts at three equidistant points.
The primary mirror was placed on the ring inside and was
supported by a layer of ½ inch thick rubber bands underneath and
all around it. The collimation of the primary mirror is done
through three bolts-nuts combined with springs which were placed
at the rear of the rings (2). It's sure that
rubber bands applied some pressure to the mirror, but the
resulting astigmatism was not too much noticeable. Oh well, who
For the diagonal holder, I went to a carpenter who carved me
one from wood with his lathe. It was of cylindrical shape with a
short rod at one end (to be attached to the support wanes), and
the other end was cut at a 45 degree angle to accommodate the
secondary mirror. I glued the diagonal mirror to the holder. To
make sure that it won't get loose, I also fastened two thin steel
plates like clips to hold it in place. The spider had been built
again by the same workshop where the primary mirror cell had been
cast. It consisted of a small round iron plate in the center,
attached to an iron ring via two thin iron rods. Even though I
tried to have curved support wanes (to minimize spike effect) by
using thin steel rods after a Sky
and Telescope article
1985, page 459), the steel rods did not stay as rigid.
As a result, I adopted a two-waned spider, instead of a regular
one with three or four. The small iron plate in the center was
threaded with three small holes through which small bolts with
springs were attaching it to the diagonal holder, also allowing
the collimation of the diagonal mirror.
The first focuser I had was made of two thin iron pipes used
like a helical focuser. However, it was not really efficient
because of their friction problem. Consequently I had to look for
another material easier to work with. I ended up in going to a
brass workshop manufacturing boat propellers. In less than a week
I was mounting a simple but very user-friendly brass focusing
mount to my tube. It consisted of two brass tubes gliding within
each other (3). The outer tube had a round base
which I had fastened to a square wooden plate with four screws.
I use two finderscopes on my telescope: 8x30 monocular
attached directly to the tube in front and a 20x60 monocular
mounted on the telescope box. In the pictures below (except the ones for the
setup process) and on the Our
Observing Instruments page you can see my original 5x40
homemade finderscope. Later on I replaced it with the current
8x30 monocular seen in the setup pictures below.
To my dismay, the tube of the telescope had been completed
long after Halley's
Comet disappeared in northern skies. Its construction took
longer than I had originally planned. For almost two years I used
the tube as it was, without any mount. I was putting the end of
the tube on the ground and just trying to hold it steady with my
arms whilst looking through the eyepiece. Although I had bought
my second eyepiece, a 20mm Erfle, from Broadhurst Clarkson and
Fuller in London in 1986, the field of view was still narrow
to do serious observing. I remember observing the opposition of
Mars and making out some surface features in May 1988. In June
1988 it was time to go to Paris, France to start my career in
banking. With my heart broken, I left my tube-scope back home. It
wasn't after my return to Turkey in fall of 1989 that I would
resume where I left in building my telescope ...
Since I have first seen Edmund Scientific's
fork-mounted reflectors on their catalogs in early 1980's, I fell
in love with the idea of using a fork mount in my future
telescope. The only pitfall was that I had no clue on how to
build one. Until I came upon another book about telescope making.
The year was 1988 and I was living and working in Paris, France.
The book was titled "Mon Telescope, Mon Observatoire,
Pourquoi Pas?" (My Telescope, My Observatory, Why Not?; 2nd
edition, 1985). It was written by the prolific astronomy
popularizer, writer and telescope maker, Pierre Bourge, together
with Jean-Marc Becker, an amateur astronomer as its co-author
(you can see a Bourge-type telescope described in the book at
That book gave me the exact idea on how to build the fork
mount I wanted so desperately. Actually I also met two young
optical technicians working at the REOSC
Optique company (manufacturer of optical systems for
satellites, polisher of ESO's VLT mirrors), also
amateur astronomers, during a visit organized by the Association
Francaise d'Astronomie to Nancay
Radio Astronomy Observatory. One of them, Jean-Marie, had
already built an exact textbook copy of Bourge-type fork-mounted
8" newtonian (can you believe my luck?). Moreover, we had at
least two observing runs with his telescope in Frettes, a small
town near Dijon, east of France, close to the Alps. So I had
enough time to examine it closely and take as many pictures as I
could. I had already decided how my future telescope would look
Another bonus feature of Jean-Maries telescope was that
he was repositioning the eyepiece to a convenient location by
rotating the tube. He had built a box similar to a
dobsonians rocker box and placed the tube inside. He used
some sort of clamp system which was loosened to turn the tube
within the box to have the eyepiece easily accessible wherever
the telescope is pointed to. This way the balancing of the tube
was also easily done, by moving it back and forth. I had a
similar box and clamp system built on my telescope (4).
As a result looking through my scope is really convenient
The lower part of the tube-rocker box is strenghtened by
triangular MDF supports diagonally placed in each corner. The
surfaces of these supports, which are in contact with the tube,
are covered with used black velvet strips to prevent the tube
For the fork arms I used 1-inch thick medium density fiber
(MDF) stock which is considerably light, strong and easy to work
with. As you can see in the pictures below, I first had to put a
frame for the arms so that they form a U shape (or two Ls
placed face to face). The bottom of the U consists of two levels
of MDF separated 5", to make the arms stronger. Just
underneath of the upper level, two sides of the U arms were
connected together by two long bolts and hardly tightened by
nuts, in order to strongly keep the arms together (5).
I fastened used ball bearing covers (bought from an auto
junkyard) to either side of the tube box as side bearings. They
formed the altitude axis. The upper ends of the fork arms were
finished in 4" wide U-shaped openings. Bearing covers sit on
these openings squarely. At the start I was thinking that I would
need to place teflon pads to provide friction, but steel bearing
covers' friction against MDF was enough to keep the whole
box-tube combination in balance. So, in a way, my
telescopes basics are those of a dobsonian after all.
To finish the fork arms I covered the framework with plywood
and applied brown furniture paint all around. I had a 2-inch hole
drilled (6) in the middle of the two bottom
levels of the U, to place a steel shaft (7) for
Right Ascension later on. And this story takes us to the next
phase in the construction of my telescope ...
By the time the tube and the fork were completed, another
important part of the telescope was still not around: the mount.
From the winter of 1989 until the end of summer in 1990 (mostly
during 1990 summer months) I used my reflector as a dobsonian.
Having not yet decided on what the mount would look like, I was
just placing the tube into its craddle and putting the fork arm
on a cardboard on the ground. Then I was moving the fork in
azimuth. Although it was not as smooth as a real dobsonian, I was
happy enough to use it in observing several objects, including
comet Levy (C/1990 K1).
However I needed an ultimate solution to place my fork mounted
tube onto a real mount, in order to start making some serious
As you know (from my story above) I consider myself as a lucky
guy (in terms of telescope making and also marriage). The AAVSO was organizing its first
European meeting in Brussels, Belgium in July 1990. I had to go
there! So I did. The first day, during one of the coffee breaks I
was meeting with several people I only knew by their pictures and
their names (such as Gerry Dyck of Assonet, MA and Rev. Robert
Evans of Australia). Then, there was this display area where
people posted their papers, pictures and observation results. I
remember that while wandering in front of the displays I stopped
in front of one booth, prepared by Belgian amateurs, showing
several pictures of homemade telescopes. And there it was,
standing amidst other pictures, a white colored homemade
newtonian (yes you guessed it right, an 8" beauty) standing on
a triangular box-shaped mount, the fork arms attached to the
mount with a pipe which was supporting the R.A. axis. Fortunately
I did not scream "Eureka!", however I took several
close-up pictures, of that one and others.
Upon my return to Istanbul from that meeting, I was working
like crazy on the mount. To the contrary of the Belgian mount I
pictured, I wanted my mount to be fully portable. So I set aside the idea of
having a box-shaped mount and chose a modular approach. Eventually, I ended up
with using two MDF boards, attached to each other with a long
furniture hinge (8), so that I can fold the
boards down for easy carrying. I also used two aluminum pipes (9)
to elevate the upper board on the ground one with an angle of 45
degrees (a rough polar alignment). Although I was going to
install just small plastic feet on the underside of the ground
board first, my grandmother who was visiting my parents gave me
another idea: why dont you use wheels to roll it
around? she asked (now I call this a family of astronomers,
yeah). Thus I placed four small rubber wheels at each corner. In
order to stabilize the ground board during observing sessions I
had five holes drilled, at each corner and in the middle, glued
large nuts in the holes and put large bolts (10)
fitting through them. When I am carrying the board to the
observing site, I roll it around easily. Then I stabilize it by
turning the bolts in and raising the board over the ground, and
thus polar aligning the scope.
I used a 15" long steel pipe for the R.A. shaft. It goes
through the holes on two bottom layers of the fork arm and is
screwed to the upper part through a plate (6).
In order to attach the shaft to the elevated board and turn the
fork in R.A. axis I glided it through two used auto ball bearings
(11). Bearings themselves were attached to the
board by reversed-U-shaped clamps made of iron. To increase the
friction and have the fork turn tighter I used a reversed wooden
U-clamp in the middle of the shaft (12).
For now the mount is an equatorial without the tracking
capability. However my plans, adopted from the French book, are
ready to include a star-tracking device. I think it will take
another couple of years before I complete it!
Numbers correspond to sections explained in the
... In the End
The construction of the my
entirely-home-built-telescope-except-the-optics had been
completed in 1990. Since then it helped me and others to see the
universe with another perspective. From light polluted skies of
Istanbul I could easily reach magnitude 13 and from my
parents summer house on the southern Marmara Sea coastline
I saw stars down to 14th magnitude. Unfortunately, I am away from my beloved telescope
again since I could not take it
with me when we moved to Boston in 1997. I am looking forward to uniting
with it in a short while and continue stargazing and observing
the heavens with it. As Emile Schweitzer of AFOEV had put it in
one of his letters once, astronomy is a field of research
requiring lots of patience. I am patient and will be
waiting to look through my 8 one night again. In the meantime, I am
admiring the skies through
Mary Ann, our
computerized 8" SCT.
Update as of September 2007
Finally! My beloved 8" scope and I are together again :o)! I have it shipped
from Istanbul to Boston, with the rest of our fine furniture. I look forward to
the night I will be observing through it again.
Update as of August 2009
Another one of my dreams come true, at last! This year I finally brought my
beloved 8" scope to the Stellafane
convention and displayed it on top of the Breezy Hill, near the Pink Clubhouse
and the Porter Turret telescope :o)! Thanks to the awesome weather, I observed
with my scope both in front of the Porter Turret telescope and the McGregor
Observatory on three consecutive nights, in August 13th, 14th and 15th! I also
got the "displayed at Stellafane" sticker
that I am now proudly carrying on my scope.
As someone mentioned it correctly during the Friday tent talks
at Stellafane in 1998 (our first convention):
"telescope making is an art of inspiration". There is nothing wrong
if you start looking at findings and ideas of other amateur
telescope makers to come up with solutions of your own when you
build your telescope. In turn, other amateurs will copy your
ideas and your scope's features and again those of many others to
build their telescopes. And this cycle will go on, forever ... Now
it is your turn to grasp some ideas from my homemade newtonian to
build your own. Good luck in your endeavor!
"It is not ... unsportsmanlike to study
closely the details of telescopes made by others and to 'lift'
this or that feature from them, provided one improves these
Albert G. Ingalls
Setting It Up
Below I post several pictures to show you how the scope's setup is done
before an observing session.
Left: Getting the components together; the base, the tube, the fork.
Right: Preparing the base; I am putting aluminum pipes in place to raise the
Left: Fastening the wooden "U" clamp onto the board to keep R.A. steel shaft
Right: Checking the collimation.
Balancing the tube within the "rocker" box.
"If there were a million amateur
astronomers with telescopes, and they were willing to let a few
thousand people each look through their telescopes, there would
be a chance for the people in the world who wanted to see to
AMATEUR TELESCOPE MAKING LINKS
Telescope Making WebRing, by Yahoo.
Annual Telescope Optics Workshop, Western Washington University.
ATM FAQ by
the Atlanta Astronomy Club.
ATM Links, by Willie Koorts.
Astronomy Daily, now includes the
former "ATM Page".
ATM's Resource List
by Bob Lombardi.
Dan Cassaro's ATM Page
Group 70, a group of amateurs
to built the largest telecope in the world.
How to Choose a
Quality Telescope for Under $500.00, by David Lent (the original link is
dead due to re-construction).
Tension Spring Dobsonian
Lin Robertson's ATM Home
Mel Bartels' Home Page
Bartels' Computerized Dobsonian
Ray Cash's ATM Website
RTMC Astronomy Expo, formerly Riverside
Telescope Makers Conference
Fransisco Sidewalk Astronomers
Astronomy ATM Web Ring
and Telescope Making, by Mel Bartels.
Making Web Ring, where this page is also listed.
SELECTED ASTRONOMICAL EQUIPMENT REVIEW LINKS
Chip Baines' Product
Descriptions and Reviews
Cloudy Nights Telescope and Accessories
Reviews, by M8 Inc.
Darwin Bagley's Reviews
Excelsis Ratings, ratings for many
instruments including astronomy equipment.
NOVAC Telescope Reviews
Rick's Low to Mid Range Telescope Review Web
Rod Mollise's SCT-User
Mailing List Home Page
by Ted Kurkowski
SkyNews Magazine Telescope Reviews
Sky & Telescope Test
Reports, pay per report.
Telescope Owner Resources, by The Open Directory Project.
Telescope Reviews by Jason
The Telescope Review Web Site, by Ed
Ting of New Hampshire. A short note: when I met Ed during my wife's and mine
first Stellafane convention in 1998, I did not know who he was. He gave me his
astronomy business card when we were observing in complete darkness. Very much
later, when I checked the card and read his name, I said to myself: "Darn! I
should have talked to him more to ask his advice on many things".
Todd Gross' Equipment Reviews
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