Re: ATM newbie with dumb question

["B. Pepin" <atmjedit@conceptsnet.com>]

Steve,

Your brother's work might be better than you think. Chances are it is an f/6
but longer wouldn't necessarily be bad. 8" x 8 = 64. In other words,
about a five-foot optical assembly. Not a Godzilla-scope.

He's already done the "hogging" for you, and there would be little sense in
redoing it if there is already a good curve to work with. Working with a
"pre-generated" (sibling-generated) curve would be a good way to learn your
way into the polishing process. If the figure is basically correct, just
clean up what is there and live with the focal length. If you want to
practice grinding for the heck of it, try a smaller blank you can make
mistakes on.

You can always make a shorter, wider-field scope on your second try if you
want more portability. An f/8 would make a great planetary scope. The longer
the focus, the better the views you will likely get of Mars, and the less
expert you will need to be to create a usable mirror figure. Heck, you could
almost leave it spherical at f/8, according to some of the list pundits.

Good Luck!

----- Original Message -----
From: The Jester, 69 <jester@zarf.org>
To: <atm@shore.net>
Sent: Tuesday, October 24, 2000 9:02 AM
Subject: ATM newbie with dumb question


>
> hello all,
>
> I will try to keep this brief... i have read all the faq's and a couple of
> books and they have great advice but i wanted to see if i could possibly
> solicit opinions on my specific situation.
>
> I have inherited a mirror project from my brother who lost interest in it
> over 20 years ago. It is an 8 inch pyrex full thicknes blank from Edmund
> Scientific, he believes it to be ground to spherical, polish work has been
> done but its not figured.  He could never get the focault tester he built
> to work right so it is now my job to see what i have and go from there.
>
> My question: I would like to decide what to do before i measure it so i
> will not change my mind out of laziness... but i am new enough to
> astronomy that i cannot make an informed decision. (obviously if he messed
> up the grinding i'll have to start over anyway, heh)
>
> I would prefer f/6 due to transportability, but if it measures f/8 i would
> have to more or less start back to rough grinding and kill the polish to
> meet that end. i have a van so technically i can transport an f/8 8" but
> it would certainly be inconvenient (i prefer a tube vs a truss design for
> ease of setup on site) BUT, if there are distinct advantages to a longer
> focal length i may well be willing to put up with the hassle...
>
> What would you do? I guess i am looking for a good all around scope that
> isnt overly suited to one type of viewing at the expense of another...
>
> Thanks,
>
> Stephen White
>
> P.S. i am a total newbie with a head full of book knowledge.  I am also
> planning on building a copyscope... and am quite looking forward to mars
> being at its closest next year, but deep sky viewing intrigues me as
> well...  I have a few cameras (olympus OM-1, OM-2 and OM-10) and may try
> my hand at photography, but thats not my primary aim... viewing is. i have
> a great hilltop dark sky site acessible :) My recent trip to new mexico
> has inspired me, the sky was so beautiful up in the mountains and high
> desert...
>
>
***************************************************************************
>                      You move like a pregnant yak
>                        http://zarf.org/~jester
>
***************************************************************************
>
>


----- Original Message -----
From: The Jester, 69 <jester@zarf.org>
To: <atm@shore.net>
Sent: Tuesday, October 24, 2000 9:02 AM
Subject: ATM newbie with dumb question


>
> hello all,
>
> I will try to keep this brief... i have read all the faq's and a couple of
> books and they have great advice but i wanted to see if i could possibly
> solicit opinions on my specific situation.
>
> I have inherited a mirror project from my brother who lost interest in it
> over 20 years ago. It is an 8 inch pyrex full thicknes blank from Edmund
> Scientific, he believes it to be ground to spherical, polish work has been
> done but its not figured.  He could never get the focault tester he built
> to work right so it is now my job to see what i have and go from there.
>
\