Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_dslr_mirrorlesss.thumb.jpg.5b348d6a5e7f27bdcb79e9356b7fc03b.jpg

Smithfire

Mirror longevity.

Recommended Posts

Hi guys

Do mirrors fair better if kept in the house? I cleaned my mirror a few months back and it is starting to go milky already. I keep it in a dry shed outside.

Many thanks

Clive

Share this post


Link to post
Share on other sites

It should be OK for ages if it's stored in a dry place.

How old is the scope and what brand is it Clive ?

"Milky" sounds like the overcoating has started to fail.

Share this post


Link to post
Share on other sites

Its a closed tube skywatcher 12 inch dob John. Probably 7 to 10 years old? Its not bad enough to significantly effect the seeing though.

Clive

Share this post


Link to post
Share on other sites

7-10 years is pretty good going for a 12", the larger the aperture the sooner it needs recoating in my experience.  :smiley:

Share this post


Link to post
Share on other sites

Hi guys

Do mirrors fair better if kept in the house? I cleaned my mirror a few months back and it is starting to go milky already. I keep it in a dry shed outside.

Many thanks

Clive

Hi

The temperature inside the 'dry' shed will cycle, day through night and with seasons.  This can cause repeated condensation on the mirror...

...as Peter D. noted, 7 - 10 years is a reasonable lifespan for a coating.

Cheers

Paul

Share this post


Link to post
Share on other sites

I suspect that you are just at the end of it's pristine life.

Seem to recall that 8 years was fair and 10 years good, and has been said a lot depends on how good the coatings, aluminium and protective, started out.

Moisure, condensation etc also tends to be slightly acidic, which does no good to the coatings.

Not sure who recoats mirrors if you decided to head down that avenue.

Galvoptics do or did - they altered their website and assorted things have disappeared.

There is Orion that might and Oldham Optics also, not 100% sure on the services provided.

There used to be someone in N London, top edge of M25 ?, that I think did mirrors but they have either disappeared or become quiet.

Share this post


Link to post
Share on other sites

Some manufacturers claim remarkable life spans for their mirror coatings, Orion Optics HiLux as an example. Predictions of mirror longevity of 25 years or so are in my experience somewhat over optimistic. I had a several large holes in an extremely well looked after 10 inch Europa that was 8 years old.

Share this post


Link to post
Share on other sites

Some manufacturers claim remarkable life spans for their mirror coatings, Orion Optics HiLux as an example. Predictions of mirror longevity of 25 years or so are in my experience somewhat over optimistic. I had a several large holes in an extremely well looked after 10 inch Europa that was 8 years old.

I'm not sure that Europa's had Hilux coatings, as standard, 8 years ago ?

  • Like 1

Share this post


Link to post
Share on other sites

I suspect that you are just at the end of it's pristine life.

Seem to recall that 8 years was fair and 10 years good, and has been said a lot depends on how good the coatings, aluminium and protective, started out.

 

Moisure, condensation etc also tends to be slightly acidic, which does no good to the coatings.

 

Not sure who recoats mirrors if you decided to head down that avenue.

Galvoptics do or did - they altered their website and assorted things have disappeared.

There is Orion that might and Oldham Optics also, not 100% sure on the services provided.

There used to be someone in N London, top edge of M25 ?, that I think did mirrors but they have either disappeared or become quiet.

 

Galvoptics are just 10 miles from me, I've had mirrors recoated there and so have several members of my local club.

http://www.galvoptics.co.uk/products/telescope-products-andamp-services/telescope-mirror-coating---primary/

Also Orion Optics and I think Vacuum Coatings recoat mirrors.

Regards, Ed.

Share this post


Link to post
Share on other sites

It said Hilux on the paperwork.

Fair enough. Might be worth mentioning it to Orion Optics as they make the 25 year claim for the product.

Share this post


Link to post
Share on other sites

Fair enough. Might be worth mentioning it to Orion Optics as they make the 25 year claim for the product.

I have a different scope, the Europa is long gone.

Share this post


Link to post
Share on other sites

Gosh ! - have I really had that scope for over 3 years now !

Thanks for the reminder :smiley:

The coatings on mine are still in excellent nick I'm pleased to say. I do keep the scope indoors though.

Share this post


Link to post
Share on other sites

I certainly keep mine indoors in our back room and feel grateful that they have an accepted allocated space to occupy in a family home. Reassuring that the scopes are kept in a dry, clean environment free from condensation. Not so reassuring that they are at least indoors 99.5% of the time currently.

Share this post


Link to post
Share on other sites

I got an Orion-USA 200mm F/4 Newt back in 2000. It was manufactured by GSO, and Orion was selling them way to cheap by mistake. So they were quite rare as Orion pulled them off the market quite quickly - once they realized their error. So I was one of the lucky few. The optics were, and are, superb. But they needed a re-coating last year. The mirror was losing it's shiny-bright nature. So that was 14 years. It was stored indoors in a warm environment.

The re-coating truly brought it back to it's original quality. If you're in the US and need a re-coat for yours, I used Majestic in New Jersey, which I do recommend. Total cost, with shipping, was $115.00.

Enjoy!

Dave

Share this post


Link to post
Share on other sites

Thanks Dave.....not in the US but darkest rural Oxfordshire, England.

I guess if i do have the mirrors recoated, then I'll have to think of a better way to store it.

Maybe if I remove the dust cover while the temperature stabilises it will let any condensation escape?

Clive

Edited by Smithfire

Share this post


Link to post
Share on other sites

My scopes are at cold outdoor temps in buildings and I now use breathable Typar to loosely cover them with. This seems to eliminate the problem so far. No frost or condensation.

  • Like 1

Share this post


Link to post
Share on other sites

Thanks Jetstream. Ill look into that. I guess its just a matter of letting the condensation escape while still keeping the dust out.

Clive

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.