Where to buy 24" + Mirrors in Australia?

Davekyn (David) · #1 21-12-2008, 08:32 PM

Hi,
Where does one buy large mirrors in Australia. The largest I can find is only 16".

tnott · #2 21-12-2008, 08:57 PM

Try Mark Sutching. Otherwise its overseas I'm afraid.

http://users.tpg.com.au/masuch/dso/

SDM in Vic. orders ahead I think and may have one you can buy.

http://www.sdmtelescopes.com.au/prices.html

Paddy (Patrick) · #3 21-12-2008, 09:03 PM

Looks like the old aperture fever has kicked in pretty quick and hard Dave!

Starkler (Geoff) · #4 21-12-2008, 09:09 PM

Quote:

Originally Posted by tnott

Try Mark Sutching. Otherwise its overseas I'm afraid.

http://users.tpg.com.au/masuch/dso/

You're in luck.

Custom made precision Newtonian telescope primary mirrors from 10" to 24" diameter

Davekyn (David) · #5 21-12-2008, 11:10 PM

Thanks guys,
I took apart my 12" gso and have pretty much got to know that scope inside and out. Not much to them really. As for SDM... No offense, but the prices seem way over the top. I am after APP not ultra specs. Mabey GSO will eventually come out with A 20" mirror.

I was checking out Orion just the other night in my don with a 19mm flat field & WOW!!!!!! The texture was amazing. I also found other other but smaller targets from my light pollouted yard but still gob smacked!

Yes, I am hooked on APP...what will $3000.00 get me in the way a mirror only? Bintel are selling the 16" light bridge for more than $3000.00!!! Seems a bit over the top as well. I figure I could spend that on primary mirror alone and now that I feel confident after pulling the GSO apart...I'll build my own "SDM...if you will...for LESS than the asking price. Sure it won't have the latest and greatest techy specs or quality & finish...but I'll still have a monster scope. Well that's the line of thinking this far.

Later...will ring Sydney Tommorow on mY break
Thanks again.
Dave

erick (Eric) · #6 21-12-2008, 11:53 PM

Great to see your enthusiasm, Dave. From what I have read, however, an element of caution? I don't think building a 24" truss reflector is a simple matter of scaling up what you have seen in a GSO 12" solid tube reflector. Apologies if I'm stating the bleedin' obvious, but I think there would be a lot of reading, designing and testing needed, as well as collecting the accumulated wisdom of the ATMers on the site here and elsewhere. Mirror cell design, flexure, altitude bearing size, balance, mirror cooling all come to mind as issues that are not simply scalable from a smaller scope? But again, this is what I have read rather than done! Best of luck and we look forward to seeing the result evolve.

Davekyn (David) · #7 22-12-2008, 06:35 AM

Absoloutly Eric...However as you obviously know, there is a wealth of I out there. Yes...I am aiming high to say the least. Perhaps a bad choice of words on my part..."not much to them"...I am no engineer, but like to do things methodicly & if I do take the plunge; I'll succeed one way or the other. Thanks for the reality check

... Perhaps the price of the mirror will be way over $3000.00 ... If over 4 Grand, I'll probably wait unroll prices drop.

GrahamL · #8 22-12-2008, 08:33 AM

Quote:

what will $3000.00 get me in the way a mirror only

gso will sell direct .. there 16 "mirrors land here for less than 3 k

Good luck ,,building your own scope is a very rewarding experiance
though in dollar terms isn't always as cheap as you imagine
hand finished custom optics , all the top shelf running gear
comes at a price .. I guess there are savings to be had within but
you lose sight of the money part ( plenty of it) as you travel this journey
The end result is well worth the effort and something you can't put a price on.

cheers graham

tnott · #9 22-12-2008, 10:08 AM

You could get a 16" GSO mirror or buy a secondhand 16" lightbridge that the owner has found too heavy to cart around and use the optics. Not necessarily going to be the same as premium optics though.

"The Dobsonian Telescope" By Kriege/Berry is essential reading before you even think about buiding a big one. There are newer designs around that are lighter and more compact, but this book has all the principles that you need to know first.

Davekyn (David) · #10 22-12-2008, 12:47 PM

I am ordering books today...I believe that is the one I am looking at now. 100% agree about needing the books & will also rigourosly research the Internet.

The idea of picking up
A cheap 16" is a good one...however if I wanted to go that size, I would just shell out the 3+ grand at bintel. The main reason I am building is at this point, I am under the impression that a 24" inch can be built cheaper than "SDM" sells Them for, and aslo it will me some time before it's being sold as
standard.

I can get a new 16" GSO mirror for $999.00 therefore was hoping a 24" may be availabe for 3-4000. Will me ringing after lunch. I hate it when they talk premium to explain the 6-9000 price tag. The quality on the GSO optics look more than good enough to me. I just want a 24" version of it. No doubt ,I'll cop the premium jargon today when I ring Sydney. Ofcourse if I was a lot more wealthier, then yea...I would know the difference first hand...even then I may still wonder on the margin, in just the
Same way I would with a new release CPU.

Will keep you posted on the quote If your interested.
Dave

erick (Eric) · #11 22-12-2008, 12:57 PM

Dave

I think that the salesperson's expectation is that someone looking for a 20" mirror or greater is not interested in a "run-of-the-mill" result. They would be experienced observers who know and can appreciate the difference between "good enough" quality and "premium" quality. And see it as well!

However, I guess that would have been said about a 16" mirror some years ago? Now we have factory-produced, reasonable (?) quality at accessible prices.

Davekyn (David) · #12 22-12-2008, 01:31 PM

It all comes down to money Eric...I have been building computers since virtually they came to be & although I can apreciate the $$$$ands I have spent on the latest & greatest, I still question the margin VS $$$$$.

It's all a matter of time in that regard, be it much slower in this hobby. Bias can be income based...not to mention too much money & not enough heart ache learning. O oh ... Starting to dribble now...

I better read up some more. Is this the book some of you guys are revering too:
Http://www.willbell.com/TM/dobtel.htm

erick (Eric) · #13 22-12-2008, 01:55 PM

Yes, that is the book.

Also go to the Obsession Telescopes site and get a copy of their DVD sent to you. I recall that it shows "behind the scenes" at the factory, so you can appreciate what is behind some of these larger truss dobs.

Ian Robinson · #14 22-12-2008, 02:15 PM

Dave ,

I'd wait til the exchange rate is going in the right direction and order one from somewhere like :
Newport Glassworks
Nova Optical
Swayze
Galaxy

You'd be looking at a lead time between 3 - 6 months once the order is placed I'd expect (unless they have one that fits the bill in stock - due to a cancelled order or maybe one made on spec).
Building the OTA and rocker box wouldn't be all that hard - the key components can all be had ready made , which only leaves the carpentry or metalwork (depending on how you want to do the scope).

Well , that's how I'd do a 24" if I decided to go for one , a lot can happen in the exchange rate in 3 to 6 months.

What surprizes me is that I've not heard of any chinese companies offering quality mirrors in the 16" --- 30" class yet. Maybe they are out there , anyone ? EDIT : found quite by accident Intane-Optics in china do parabolics to 33".

cristian abarca · #15 22-12-2008, 02:23 PM

Can I suggest you make the 12 inch into a truss Dob first before you embark on a 20 inch. I built a 10 inch using Berry's book and it's not as easy as it sounds, but it is rewarding. Things always work out better the second time around.

Cristian

Davekyn (David) · #16 22-12-2008, 02:40 PM

Excellent idea...I understand what your getting at & agree I could gain some much needed skills.

Thank for the sugesting it. "Excellent idea!!"
PS...thanks Eric & Ian, will most certainly follow your advise as well. Glad I was able to talk about this with you all.

erick (Eric) · #17 22-12-2008, 02:42 PM

Dave, you might like to look at what Tim has done with a 10":-

http://www.iceinspace.com.au/forum/s...ad.php?t=38956

This would be scalable to a 12". Perhaps not to 24" without mods?

Paddy (Patrick) · #18 22-12-2008, 03:42 PM

One more suggestion from someone who has never made a telescope is that before you get too far in to deciding what your scope will be, it might be worth going to some of the bigger star parties and having a look at and through some big scopes. I found this very useful before my recent acquisition. I was tossing up between a 16" or 18" and to look through both size scopes showed me that there was not a great difference, but looking at them convinced me that the extra weight and bulk of an 18" was something that I wouldn't want. I reckon a 24" would be a big bit of kit to move around, although you would certainly collect a lot of light. I am no expert on optics, but I would also imagine that the bigger the mirror, the more critical good quality might be.

Starkler (Geoff) · #19 22-12-2008, 04:29 PM

Something to bear in mind is that mass produced large mirrors greater than 12" in size have only been around for about a year or less.

You wont get a scaled up mass produced mirror from a chinese maker at chinese prices. Large mirrors are specialty items and come from small manufacturers in small volumes.

For a reality check the last price I heard on a new 16" mirror that wasn't a GSO was about $3k. Pyrex blank prices have gone up since then and our south pacific peso, down.

Satchmo · #20 22-12-2008, 04:57 PM

Quote:

Originally Posted by Ian Robinson

I'd wait til the exchange rate is going in the right direction and order one from somewhere like :
Newport Glassworks
Nova Optical
Swayze
Galaxy

Guess it was this same attitude to local industry that closed your local Newcastle steelworks