Re: ATM 90mm f-11 APO

["Brian S. Boothman" <brian@boothman.net>]

 I don't mind spending some money on the materials
as long as it is in the hundreds and not the thousands
of dollars.
  I have done some remedial polishing on commercial
optics with good results. I feel that if I am going to
spend the time grinding and polishing I would like to
do it on a scope that is the best I can afford.
Not the biggest.



Dan Chaffee wrote:

> Brian Boothman wrote:
>
> >I am still in the contemplation stage of this project.
> >I was thinking that at only 90mm the glass could not be
> >all that expensive. Perhaps I was wrong.
> > I was thinking of a refractor because I am limited to
> >a small space and the mess associated with a large mirror
> >is not an option in my location.
>
> I don't see why a 6" mirror would take noticeably more space
> with the project than 90mm of two or three lenses. It would
> out perform it in every way except image stability and blackness
> of background. If you're cleaver enough or copy someone else
> who is, you can make a 6" f/6 newtonian shorter in storage than
> any 90mm apo I've seen.
>
> I'm building a  refractor too, but if I were to do one
> that small, a say,  f/14  90mm crown/flint doublet would be so
> close to unobtrusive color that an "ED" or fluorite combination
> wouldn't be warranted in my book. Much cheaper too. If
> this is your first optics endevour, I recommend staying away
> from expensive glasses.
>
> D. Chaffee