is my secondary mirror damaged?

[superjody]

does anyne know whats going on here?? my secondary mirror looks a bit funny, is it time for a new one?

[http://stargazerslounge.com/attachment.php?attachmentid=76285&stc=1&d=1325590658]

[Merlin66]

Looks like a re-coat would be in order....

[Moonshane]

try cleaning it first. did you ever sneeze when changing an eyepiece?

[terrym2002uk]

Thats looks like the coating has oxidised, of which the majority appears to have started from the mirror edges.

Has it ever been cleaned in the past? Previous cleaning may have effected the the protective coatings. I suspect you would need to get this recoated.

What state is the primary in?

[superjody]

The primary seems fine, but im not sure about it being cleaned in the past, I bought it secondhand. It was a little tatty on the secondary but has got a lot worse. How much is a re coat? I think there is a secondary mirror on astro boot for £30

[Moonshane]

I'd have thought a recoat should be no more than about £20?

see also telescope diagonal secondary mirrors

[Moonshane]

and telescope mirror aluminising, silvering, coating, realuminising, resilvering, recoating

[Moonshane]

Orion optics also offer a service Mirror Recoating

[ecosse]

If that's how much a recoat costs why do people get so concerned when it comes to washing mirrors? Or am I missing something?

[Moonshane]

true enough, it's not the end of the world costwise, especially when it's a good quality mirror.

[LukeSkywatcher]

Is it not possible to buy replacement secondary mirrors for your brand scope (any scope)?

Wouldnt it be cheaper to replace then recoat?

I ask because i dont know.

[barkis]

Recoating your secondary won't be very expensive.

You may have to wait a while though, if the Aluminiser you choose to do it for you doesn't have a batch to do, as it isn't viable to fire up the machine for one small job.

Ron.

[derekm]

Orion optics also offer a service Mirror Recoating

So do Galvoptics, who have recoated the mirrors for our local society.

telescope mirror aluminising, silvering, coating, realuminising, resilvering, recoating

[Moonshane]

indeed Derek - that was the one of the other links. the OP is closer to OOUK though so I thought might prefer to hand deliver?

[michael.h.f.wilkinson]

Re-coating is the way to go if the glass surface is OK. People worry about washing/cleaning mirrors only in part because of fear of removing coatings. The much bigger worry is that you might scratch the surface, e.g. due to a tiny bit of sand or other hard substance. While a little scratch might not impair overall performance as much as you might expect, the damage is irreversible. Re-figuring a mirror has a very different cost compared to re-coating.