fixing GS optics

[Astroman]

Hi all,

Something has been stirring around my head for a while now..

Is there a way to correct the imperfections in GS mirrors? From my understanding they are about 1/12th wave and have numerous imperfections from the mechanical grinding. I also understand that a 1/10th wave mirror is better, but can this be achived with the GS mirrors.

Any idea who does this and at what cost would be involved for say a 8" - 16" mirror. Would it be practical to do this?

[janoskiss]

The smaller the number the better the mirror. So 1/12 is better than 1/10. 1/12 is very good.

The "wave" number is a measure (RMS??) of the deviations from the perfect parabola shape as a multiple of the wavelength of light (green I presume). So the smaller the better.

[Starkler]

Give Mark Suchting a pm. He is a member of this site and has a great reputation in Australia for producing premium mirrors.

As a ballpark figure, I was quoted $900 to refigure a 16 inch f4.5 conditional upon no astigmatism being present.

You have to ask yourself, having a premium mirror you would then want a better secondary. GS uses non-standard sizes so you would have to replace the secondar holder/spider. Then maybe that ota tube with rust spots isnt so good anymore, or your not happy with the focuser/base/whatever.
Is it worth spending the money for a Rolls Royce mirror in a Holden body ?

[Astroman]

I see where your getting at geoff, I guess then it would be turning into an atm project rather than a quick fix.

[Starkler]

Just to reassure you, GS mirrors by and large are of a pretty good standard. No they are not premium mirrors, but 19 nights out of 20 you probably wouldnt see a difference anyway.

[Astroman]

thanks again geoff, I guess I shouldnt worry too much, if they wernt any good75% of the people on this forum wouldnt have bought one.

[mickoking]

Just purchased my second one ;)

[janoskiss]

After reading Geoff's post, for the those unfortunate enough to get a bad mirror, I was just going to suggest just that, Micko. So you were one of the 1-in-20 unlucky ones. But it's still cheaper to get another mirror than have the one you have reground, right? :)

[ving]

id say so steve, i cant remember prices but i have seen plenty of mirror advertised in shops that were very reasonably priced :)