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Old 11-12-2016, 02:46 PM
jonosheehy (Jonathan)
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Where to source first / front surface mirrors for binocular mirror mount?

I have just purchased a pair of Acuter 15 x 70 binoculars (currently on a great special at that link, by the way: $130, down from $280, and the store homepage offers a $10-off Christmas coupon too; no, I'm not affiliated in any way ) with the intention of making a binocular mirror mount (guided by these instructions from Sky at Night Magazine).

But..... Sourcing first/front surface mirrors in Australia hasn't proven easy.

Can anyone help or give advice regarding this, please?

In the event that I can't get something suitable in Australia, a couple of international options I have seen include:
  • firstsurfacemirrors.com (quotes US$26.67 for a 6" x 8" x 6mm glass mirror, + US$82.63 postage)... I wonder how good the optical quality is on that mirror? Good enough for 15 x 70 binoculars? How about bigger binoculars, if I upgrade in the future (and purchased a bigger mirror up front)? Their info implies it is probably "1λ optical grade", but also says they have available λ/4 optical grade "for superior surface flatness, which is ideal for applications where the reflection is being magnified." I don't know about pricing on the latter.
  • this eBay listing (12" x 12", 96% reflective optical grade mirror for US$19.95 + US$33.57 postage)... Again I wonder how good the optical quality is on that mirror, and what size binoculars it could optically support?

Again, any advice about this whole operation would be much appreciated!

Thanks,

Jonathan

Last edited by jonosheehy; 11-12-2016 at 03:04 PM.
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Old 13-12-2016, 02:09 AM
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billdan (Bill)
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Good luck with your quest Jonathon, I think you will have to import one.

I have tried this technique before using a small 8 x 6 inch bathroom mirror. I just leaned the mirror against the Obs wall while I sat on a bench looking downwards. Focus was hard to achieve and the astigmatism was woeful. One other thing is don't use too small a mirror or only one half of the binos will show your object, unless its dead centre of the mirror.

Given what I said about the astigmatism go for the best optical grade you can afford, you really need the mirror to be optically flat.

Cheers
Bill

P.S. I just noticed this was your first post, welcome to IIS Jonathon, let us know how you go with the project, it could help others wanting to do the same.

Last edited by billdan; 13-12-2016 at 02:22 AM.
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Old 14-12-2016, 12:00 AM
jonosheehy (Jonathan)
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Thanks, Bill.

I can imagine results with a little bathroom mirror, um, shall we say left a little to be desired. Yes, the optical quality of whatever I select will be enquired after first.

Yes, that was my first post, though I've been a member for some time. I tend to 'mine' forums when I have specific enquiries, rather than post to them. But on this topic I really was getting very little, so thought I'd ask.

I will post updates here to help others like myself.

In the meantime, anyone else have any experience buying first surface mirrors for astronomy?

Jonathan
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Old 14-12-2016, 01:43 AM
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astroron (Ron)
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Quote:
Originally Posted by jonosheehy View Post
I have just purchased a pair of Acuter 15 x 70 binoculars (currently on a great special at that link, by the way: $130, down from $280, and the store homepage offers a $10-off Christmas coupon too; no, I'm not affiliated in any way ) with the intention of making a binocular mirror mount (guided by these instructions from Sky at Night Magazine).

But..... Sourcing first/front surface mirrors in Australia hasn't proven easy.

Can anyone help or give advice regarding this, please?

In the event that I can't get something suitable in Australia, a couple of international options I have seen include:
  • firstsurfacemirrors.com (quotes US$26.67 for a 6" x 8" x 6mm glass mirror, + US$82.63 postage)... I wonder how good the optical quality is on that mirror? Good enough for 15 x 70 binoculars? How about bigger binoculars, if I upgrade in the future (and purchased a bigger mirror up front)? Their info implies it is probably "1λ optical grade", but also says they have available λ/4 optical grade "for superior surface flatness, which is ideal for applications where the reflection is being magnified." I don't know about pricing on the latter.
  • this eBay listing (12" x 12", 96% reflective optical grade mirror for US$19.95 + US$33.57 postage)... Again I wonder how good the optical quality is on that mirror, and what size binoculars it could optically support?

Again, any advice about this whole operation would be much appreciated!

Thanks,

Jonathan
I got mine many years ago from a mirror and glass company in Albion Brisbane, I wouldn't even know if they exist anymore.
Have look on line or the phone book for a glass company in Albion you may just strike it lucky.
Ring around glass fitters or companies,there is bound to be one that sells first surface mirrors.
Cheers
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Old 15-12-2016, 05:07 PM
fsphotography (Frank)
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1st surface mirror.

Some time ago i purchased two f.s.m. from a chap in Canada.
They measured 9.5''x4.5''x1/2'' sealed in packages marked for the US military.
They are described as ''Periscope FSCM'' followed by by various numerals.
The seller said they were for submarines but I've since come to believe they are Tank periscope mirror's.
According to him they came from SURPLUS SHED. I really don't know if they are still available but it could be worth contacting them.
My intention was to do what you are planning,just haven't got around to it,but with the little bit of testing with temporary setups they appear to be top quality. From memory i think i paid $25us each + shipping,in the parity day's.
Could be worth a try.
Frank.
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Old 17-12-2016, 07:06 AM
miker
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This is the supplier used in the article...

http://www.scientificmirrors.co.uk/F...rror-vcltd.htm

Maybe send them an email.

Looks like an interesting project.

Michael
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Old 17-01-2017, 09:10 AM
jonosheehy (Jonathan)
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The outcome of my research

Thanks for your replies (and sorry for my very slow one it's been a very busy holiday season).

Regarding locally sourced mirrors, I called ~10 glass and mirror companies around Brisbane (and then some of the companies they suggested trying), with no success. In most cases, I had to explain to them what a front/first surface mirror is. Two companies did have FSM, just not what I'm after. They both had it only on 2mm glass, and couldn't guarantee quality (one of them said waves would be visible under magnification). One mentioned that their FSM are for use by hobby artists in kalaidascopes; they import direct from America. If anyone is still interested, the 2 companies are Hartley Williams & Co Pty Ltd, Brendale and Albion Glass & Mirror Co Pty Ltd. Conclusion: Fail.

This left me with overseas options:

Frank, SURPLUS SHED did have some first surface mirrors, but nothing big enough to do the job with a single piece of mirror, as is my intention.

I contacted firstsurfacemirrors.com to ask about the optical quality of their 1λ and λ/4 FSM, and this was what they had to say:
Generally, our standard 1/4" glass mirrors work great without blurryness. Our 1/4" glass mirrors (1λ) are clear up to 15x magnification and the λ/4 mirrors are clear up to at least 60x. The cost of small λ/4 mirrors isn't too high but a large mirrors, such as the 12" x 12" you mentioned would cost $900. The price calculator for these is here.
Since they won't guarantee their standard 1λ FSM past 15x magnification (I was hoping to at least get a mirror guaranteed to work on the next size up from my current binoculars (i.e. at least work on 20x80 binos), since I'm paying the extra to import mirror). It is quite possible (according ot another expert opinion I received) that it might work, but I need someone to guarantee it before I fork out the money. And the λ/4 mirror is just way too expensive. Conclusion: For anyone else out there looking for FSM, this company is still definitely an option to consider.

I contacted Vacuum Coatings Ltd. in the UK (thanks for pointing me to them, Michael) and they have wound up being the winner. My interaction with with their Terry Pearce was very confidence-inspiring (he's the other 'expert opinion' I mentioned, above). Both on this page and in his correspondence with me, he guarantees his FSM to work with 20x80 binos provided the piece of FSM has been personally selected and optically tested (i.e. you need to tell them that you need it to work with 20x80s when you place an order). This really inspired confidence for me knowing that someone who knows their stuff has personally optically tested my piece of FSM and is guaranteeing it to work with 20x80s. He selected a piece for me that is 8 1/4 x 12 inches and is charging me 36, plus 24 p+p (60 total = ~AU$100). I'm happy, and am proceeding with the order.

Thanks again for all your input. I will plan to post pics and my experience when I have it all put together!
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Old 18-01-2017, 09:53 AM
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All you need now is for it to arrive in one piece.

Dave
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Old 18-01-2017, 10:35 AM
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astroron (Ron)
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Good to see you having some success Jonathan
My piece of glass would have not been any good for you anyway.
Best of luck on your project.
Look forward to the end results.
Cheers
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