ATM Question

I've got the urge to build my own scope, should I buy the mirror ready to
fit for a first build or start from scratch? I enjoy a good challenge, and
time is not really an issue. I will have to read up on the subject again as
its a couple of years since I studied optics.

Regards
Graeme

gp.skinner wrote:
I've got the urge to build my own scope,

See:
http://astunit.com/tonkinsastro/atm/beginner.htm

Best,
Stephen

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gp.skinner wrote:
should I buy the mirror ready to fit for a first build or start from
scratch?

Graeme

I built a 10" Dobsonian a couple of years ago and it's good fun. I bought a
complete mirror set from Orion Optics which was where most of the money was
spent (£365) but I also treated myself to a right angle finder (Orion £96)
and a low profile Crayford style focuser (Moonlight Telescope Accessories
$165). Total cost including the plywood and cardboard tube was probably in
the region of £600 but I could've spent less overall if I'd tried harder.

I've read up on mirror making and quite fancy having a go. I've recently
purchase "The Dobsonian Telescope: A Practical Manual for Building Large
Aperture Telescopes" written by David Kriege and Richard Berry. I'm looking
into finding a 20" mirror blank at the moment. The way I see it is that
I'll never be able to justify thousands of pounds of a Meade/Celestron etc
or even thousands on a finished large mirror so the only option I've got is
to grind/polish my own. Although I'm sure there are people that will say
"start with something smaller", from what I've read you need time and
patience to make a good mirror not really amazing talent. It may take me
longer to make the mirror and it may not turn out as good as one made by a
professional optician but it'll be cheaper and I've no doubt it will yield
good views so long as I'm careful and take my time.

So it really depends on how confident you feel and how much workspace, time
you have versus how much money you have to spend on optics. For example I
could but a 500mm primary for the bargain price of £1730 or I could give my
own a go and spend between £320 - £540 (depending on glass used in the
blank) plus the time taken to make it. Obviously after it's been ground and
polished I'd have to get it coated but that's about £100. It's still half
the price of a ready made one.

Anyway here are some URL's that may help.
http://www.galvoptics.fsnet.co.uk/ click product/telescope mirrors. They do
kits, blanks and finished mirrors.
http://www.beaconhilltelescopes.mcmail.com/ also do blanks (though not as
big), kits and finished mirrors.
http://www.greenwich-observatory.co.uk/ various stuff but the only place I
found the Kriege/Berry book available in the UK. This book although is all
about large truss style Dobs has an appendix about mirror making and is a
very good source of building info/tips.
http://www.orionoptics.co.uk/ various stuff again and very good quality
finished mirrors if you want to go that route (only upto 350mm though).
http://www.focuser.com/ USA supplier of low profile focusers.

And some ATM sites I've found good info from.
http://www.astrosurf.com/jwisn/20inch.htm
http://www4.tpgi.com.au/users/daveg/index.html
http://pong.telerama.com/~mdholm/atm/cells/
http://members.shaw.ca/fvas2/index.htm very good stuff on the "how to" of
mirror making/testing etc.
http://www.newportglass.com
http://pages.infinit.net/asmprod/ just had a quote for a 20" mirror blank
plus shipping from Canada from these guys.

HTH
--
Regards
Andy

gp.skinner wrote:

I've got the urge to build my own scope, should I buy the mirror ready to
fit for a first build or start from scratch? I enjoy a good challenge, and
time is not really an issue. I will have to read up on the subject again as
its a couple of years since I studied optics.

Regards
Graeme




As a total beginner I honestly wouldn't bother with grinding your own
mirror to start with. You'll have enough to cope with anyway without
worrying about making the mirror.

I've just built my first telescope - see here
http://www.thenewports.f9.co.uk/blogger.html

I recommend you start off with doing a small one (mine is 110 mm) and
you will learn loads. Then if you feel confident you can build a bigger
one, and build a better one based on the experience and lessons learned
from the first.

There is a guy on ebay selling 110 mm TAL mirrors and also secondaries,
for about 30 quid together.


I used the "Build your own telescope" book by Roger Berry. You can get
it from here :

http://www.earthandsky.co.uk/

Very nice people who run this web site by the way :-)

Use this as a guide not a bible, feel free to chop and change his
designs (I built a dobsonian 110mm, his 4.5 equivalent uses a home made
equitorial mount).

Any more questions on this, only too please to help.

On Mon, 19 Apr 2004 12:47:00 +0100, "gp.skinner"
wrote:

I've got the urge to build my own scope, should I buy the mirror ready to
fit for a first build or start from scratch? I enjoy a good challenge, and
time is not really an issue. I will have to read up on the subject again as
its a couple of years since I studied optics.

Regards
Graeme

My 17.5 Dob is looking for a good home g. See
http://home.freeuk.com/m.gavin/bigdob.htm

My 17.5 Dob is looking for a good home g. See
http://home.freeuk.com/m.gavin/bigdob.htm

I'm afraid to ask how much (as the saying goes if you have to ask you can't
afford it!). Would fit nicely in my garden though.

Graeme