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peterstrapp

Time for mirror re-coating?

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Hello,

I'm looking for some advice on the mirrors in my 8" GSO telescope. The secondary looks quite bad. The primary has marks, mainly near the edges but is also covered in an orange/brown mottled pattern... as well as a surprising amount of dust and fur :tongue:. Is it time to have the mirrors re-aluminiumised and over-coated? How bad have other people's mirrors become before having them re-coated? Did you notice much of a difference afterwards?

I'm thinking of sending the mirrors to Vacuum Coatings Ltd but would like to know your thoughts before I do.

Thanks,

Peter.

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Find out the full cost first, including postage and everything, simply TS sell GSO mirrors and an 8" f/5 is €188, the f/6 is €177, that is about £160 for the f/5 and a bit less for the f/6. TSMirrors.

If whatever has damaged the glass then I don't think they cannot resurface it to remove pits, and if they can do anything (fill with epoxy and resurface ??) then that again costs.

Secondary's look like they are about €30.

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I didn't think the the glass was damaged however another member has just sent me a message including "fungus on glass can eat through coatings and etch the glass". I'm not so sure now. Hopefully it is just the aluminium that has degraded as a new mirror would be around €200 (it's f/4).

Vacuum Coatings Ltd would be around £75.

Orion Optics would be a bit over £100.

I'll send some photos to both and ask for an evaluation.

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it does look like failed coatings to me. I'd go to Orion Optics as given their proximity (Crewe) you could take the mirror to them and ask their opinion about the cause. I'd recommend the HILUX coatings or make sure you get a silicone dioxide overcoat which is probably included in the price you stated. you'll almost certainly not see a major difference at the eyepiece afterwards.

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Orion optics are in Newcastle under Lyme

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oops. they have presumably moved since I last went then!

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They'd only been there a few weeks before I picked my mirror up Shane

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One of the few cases where a re-coat could be recommended!  :smiley:

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Im surprised you managed to get in touch with galvoptics as they were terrible when I tried them.

I had mine recoated at Orion Optics who did it in less than a week, shame it came back in worse condition than it went in and they showed thwir winning customer service which means I wont be using them directly again.i would ask initially for a diagnosis on your mirror before you agree to any work

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Im surprised you managed to get in touch with galvoptics as they were terrible when I tried them.

I had mine recoated at Orion Optics who did it in less than a week, shame it came back in worse condition than it went in and they showed thwir winning customer service which means I wont be using them directly again.i would ask initially for a diagnosis on your mirror before you agree to any work

I've used Galvoptics lots of times as they are only 10 miles from me, can't say I've ever had a problem with communicating, or the work they did.  Maybe they were short staffed with holidays ?

Many of us would be interested in the recoating problem with Orion Optics, perhaps you could let us know what was wrong please ?

The only other recoating firm I know of in the UK is Vacuum Coatings  http://www.vacuumcoatings.co.uk/

Regards, Ed.

Edited by NGC 1502

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The problem I had with galvoptics was with contacting them, they dont answer emails and I like to get get quotes for work in writing.many people agreed that they dont answer emails.

I did a write up about orion optics in the supplier review section over a year ago :)

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The problem I had with galvoptics was with contacting them, they dont answer emails and I like to get get quotes for work in writing.many people agreed that they dont answer emails.

I did a write up about orion optics in the supplier review section over a year ago :)

Found your write up in the supplier review section, shame about those probs.......

I've always phoned Galvoptics and got a prompt answer, maybe lo-tech is the way to go with them  :smiley:

Cheers, Ed.

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I did eventually ring them about a mirror blank they advertised on their site but they told me they couldn't get them.they still advertise the big blanks now and still cant supply them.the guy I spoke to on the phone didn't seem interested and couldn't get me off the phone quick enough!!

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I've received the mirrors and they look flawless! It took two weeks, just as Galvoptics estimated. I didn't have any trouble getting in touch with them by phone and they were friendly. Now I just have to find the centre of the mirror and affix a Catseye Hotspot. If anyone has any suggestions on how best to accurately apply the sticker please let me know. So far the plan is to use the template that came with the Hotspot, however, I have read that this method may not be accurate enough for the auto collimator.

Peter.

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I have just sent my 6" primary to Orion Optics, will report back.

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Hi peter, nothing looks better than a newly coated mirror. I bet you can wait for first light.

Hope you get clear skies soon,

Cheers

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http://So far the plan is to use the template that came with the Hotspot, however, I have read that this method may not be accurate enough for the auto collimator.

I applied my Catseye triangle with the template and put my mirror back into the same position on the cell and in the scope.My collimation did not change from the OOUK applied center dot,and I can get all my reflections stacked with the AC.My guesstimate is that I am within .015" of center.My views support the fact that the scope is well collimated.

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nice job on the mirrors mate, the template you have with the hotspot should be good if applied correctly

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They look wonderful! When do we get some pics ;-)

I'm itching to try it out but predictably, after a few weeks of beautiful sunshine, the storm clouds have rolled over for the weekend. I'm hoping that the combination of a re-coated mirror and the telescope being auto collimator aligned for the first time will result in some improved pics though.

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Orion Optics re-coating completed and back within a week.

Very impressed with service and quality of finish.

Went from this:

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To this:

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Thats good to know, thanks for the update.

Was that a standard coating or HiLux?

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I understand they only do Hilux, there was no option on the booking form.

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