Jump to content

Banner.jpg.b83b14cd4142fe10848741bb2a14c66b.jpg

Does this mirror need to be cleaned?

steveb1977

Recommended Posts

  • Replies 49
  • Created
  • Last Reply
Moonshane

Moonshane

Posted
Posted

Yep, it's dirty, needs cleaning then a re-coat. Just pack it up and send it off. Let the experts do it. Otherwise use it as paperweight.

seems a bit negative? cleaning a mirror is a simple process and although there's clearly a benefit to paying for experts to recoat when needed, in this case the end result seems to suggest that there's a lot of life left before a recoat is necessary.

Link to comment
Share on other sites
Dark Matter

Dark Matter

Posted
Posted

seems a bit negative? cleaning a mirror is a simple process and although there's clearly a benefit to paying for experts to recoat when needed, in this case the end result seems to suggest that there's a lot of life left before a recoat is necessary.

No, I'm not being negative. Have you actually seen his mirror? No, nor have I. So going by the photo, it looks as though it does need cleaning and probably re-coat. If a mirror looks 'milky' it's time for a new coating.

If it looks dusty then wash in in distilled water, but if it's both then for a few bucks spent, he gets back a shiny medal. Question is. How did the mirror get so dirty in the first place and why?

I've been an astronomer for 60 years and have built many scopes and observatories in my time for many people and nothing is worse than having a dirty or milky-looking primary mirror.

Link to comment
Share on other sites
Moonshane

Moonshane

Posted
Posted

the comments subsequent to the OP and the photo after cleaning http://stargazerslounge.com/topic/178676-does-this-mirror-need-to-be-cleaned/#entry1844299 suggest that it's in good enough condition for now to get a good few years' use. I don't debate that a recoat would be a good idea in due course but any benefit currently based on what he tells us in his posts would seem dubious.

surely a few years' use in an open system, would result in a mirror with a fair degree of dust and the odd water stain which I consider normal and certainly not deletorious to the views obtained (except perhaps at very high power on very bright objects and even then....)

clearly you seem very experienced and have a view but dust on a primary certainly does not bother me at all.

Link to comment
Share on other sites
steveb1977

steveb1977

Posted
  • Author
Posted

Yep, it's dirty, needs cleaning then a re-coat. Just pack it up and send it off. Let the experts do it. Otherwise use it as paperweight.

No, it didn't need a recoat, the clean has worked fine. Telescope has been in storage for a few years so could be damp or condensation that got to it. Think i'll use it to have a look at Jupiter later rather than using it as a paperweight!

Cheers for the comments all the same.

Link to comment
Share on other sites
Dark Matter

Dark Matter

Posted
Posted

No, it didn't need a recoat, the clean has worked fine. Telescope has been in storage for a few years so could be damp or condensation that got to it. Think i'll use it to have a look at Jupiter later rather than using it as a paperweight!

Cheers for the comments all the same.

Glad to hear this, mate. Just make sure the scope's mirror is pointing downward when not in use - stops dirt and dust falling on same.

Aside, many years ago I saw a brand new 12" primary covered in scratches. I asked the owner why is this? and his reply was...."Oh, I just wiped it with this rag".

Turns out the rag was covered in workshop grinding dust! The mirror was stuffed and he had no more money for a new one. It's true, some mothers do have 'em.

Link to comment
Share on other sites
Moonshane

Moonshane

Posted
Posted

Glad to hear this, mate. Just make sure the scope's mirror is pointing downward when not in use - stops dirt and dust falling on same.

this certainly works with short tube, small reflectors but there's no way I'd leave my 16" five foot long f4 solid tube with the primary mirror pointing down. as with all things we do in life and astronomy, it's about compromise and doing your best with your equipment, budget, skills and experience.

Link to comment
Share on other sites
Moonshane

Moonshane

Posted
Posted

not sure about that - most moderators love a good debate as much as the next 'man' (we're not all men thankfully), it's when it gets a bit rude, aggressive, personal or against the CoC (or is banging on about the for sale section) that mods get upset. we're members of SGL and astronomers too don't forget. :smiley:

Link to comment
Share on other sites
Doshy

Doshy

Posted
Posted

It's always a bit odd when you read a provocative post on SGL. Generally it's just full of nice people, well that's what I've found anyway.

My mirror will have to be utterly filthy before I'd consider removing and cleaning. I store it standing upright as it came with a bin lid style cover for the primary.

Phil.

Link to comment
Share on other sites
skir

skir

Posted
Posted

I use 4 different forum's and this one is the most friendly and well mannered of the lot. The least friendly one I rarely post on and mainly use as a source of very good extensive information. If you don't do your research before asking on that one they'll tear you apart!

Sent from my Nexus 7 using Tapatalk 2

Link to comment
Share on other sites
  • 7 months later...
Darkmatter

Darkmatter

Posted
Posted

Job done and I'm happy (and relieved!) with the results.

attachicon.gifmirror.jpg

A rinse with tap water followed by soaking in soapy water for 10/15 minutes. Minimal use of cotton wool on the worst area followed by a rinse with tap then deionised water. Just the soaking in the soapy water did most of the cleaning. Safely back in the scope and ready to go. Scope could probably do with a touch up as well!

attachicon.gif8.75 Inch Scope.jpg

Thanks for all the advice and opinions.

Looks good what cleaning agent did you use? :)

Link to comment
Share on other sites
  • 2 weeks later...

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.