From: "Chris Feller" 
To: kb7h{at}onemain.com, atm{at}shore.net
Reply-To: "Chris Feller" 


In my post I forgot to mention the focal ratio it is an F5 mirror with a
radius of curvature of 81.5 inches.

Thanks Chris






>From: "Ken Hunter" 
>To: "Chris Feller" ,
>Subject: Re: ATM Waineo null test sphere figure question
>Date: Thu, 9 Jan 2003 23:09:14 -0600
>
>Hi Chris...
>
>Subtracting .095 from each reading, there is only 2 thousandths of an inch
>middle to edge. How accurate can you measure the difference? If you can
>measure to the next decimal point consistantly (.0001) then you can improve
>your mirror given good technique and time. If your limit of measurement is
>only to the nearest ONE thousandth of an inch, you should call it done as
>the
>next measurement session may give you different numbers with no change
>in the actual surface.
>
>Personally, if I can measure the difference, it isn't good enough on a
>sphere.
>That being said... the statement has to be modified for certain special
>cases.
>(like f-3 for instance) where as you say it most probably will be made
>worse.
>you gotta know your limits... What is the fl of that 8 inch glass?
>
>Ken Hunter
>
>----- Original Message -----
>From: "Chris Feller" 
>To: 
>Sent: Thursday, January 09, 2003 10:31 PM
>Subject: ATM Waineo null test sphere figure question
>
>
> >
> > I am in the process of figuring an 8 inch sphere with a 1 inch hole in
>the
> > center.
> > The figure is quite smooth but there is still a very subtle oblate
>spheroid
> > present.
> > Using a 3 zone Couder mask the results are listed below
> >
> > Zone I   0.097
> > Zone II  0.096
> > Zone III 0.095
> >
> > My question is how good does the figure have to be to get good results.
> > My concern is that the more I work the mirror the more I risk making
>things
> > worse.
> > This is the third mirror I have made however I made the other two 15
>years
> > ago so I am not very experienced.
> >
> >
> > Thanks Chris
> >
> >
> >
> >
> >
> >
> > _________________________________________________________________
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> >


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