From: "Dwight K. Elvey" 
To: atm{at}shore.net
Reply-To: "Dwight K. Elvey" 


>From: "Jerry B. Hillman" 
>
>Hi all,
>I am ready to start parabolizing my 16.5" mirror but first I want to
>determine exactly where I am.  I didn't use the ronchi test with my 10" so I
>am still learning how to interpret problems shown with the Ronchi. The link
>below shows a current pic of the ronchi test on my mirror.  Any evaluation
>would be appreciated. Also any web links with information concerning
>problems and how the Ronchi test shows them would be helpful.  The archives
>have lots of references but most of the associated links are dead.
>
>http://www.convertabarn.com/Page%202.htm
>
>Clear skies, Jerry

Hi
 Your page says that you are ready to parabolize. I don't
think this is a good idea with as much TDE and possible astigmatism as
shows in your Ronchigram. You have to remember that the Ronchigram is not
all that sensitive. Any issues you see here will be major issue in the
finished mirror. Bring it closer to a sphere before you attempt to figure
it, would be my advice.
Dwight

--- BBBS/NT v4.00 MP