Re: ATM "Un-scratching" a mirror?

[Stephen Tonkin <sft@aegis1.demon.co.uk>]

ran@netgate.net wrote:
>It looks like most (all??) of
>the scratches didn't go past the aluminum layer,  and I might be able to
>get away with just recoating. 

I have seen a few old mirrors that look like this. The glass is not
necessarily damaged so, as you say, you may get away with recoating.

>The "optics for newbies"-level books say
>that,  in theory,  all I have to do is blacken the scratches,

IMNSHO that is utter twaddle! The blackening will almost certainly
result in worse image degradation than do the scratches. If there are as
few as you say, It is unlikely you will be able to detect their effect
anyway. To put things in perspective, a 4-vane spider and secondary is
optically equivalent to having two large diametral gouges and a socking
great chunk knocked out of the centre of the mirror.

-- 
 Stephen Tonkin
(N50.9105 W1.829)
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 UK Amateur Telescope Making - <http://www.aegis1.demon.co.uk/atm.htm>
ATM and Astronomy Books - <http://www.aegis1.demon.co.uk/books/books.htm>
  The Astronomical Unit - <http://www.aegis1.demon.co.uk/astunit.htm>
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