Re: ATM Compliant Focuser

["andrew barrett" <barrett@jolt.mpx.com.au>]

Hi Donald

>Is your new scope a cassigrain? The main reason for moving either the
>mirror or secondary in a cassigrain is to take advantage of decrease of
>the travel distance that the focuser has to move and that accessories

No. The new scope is newtonian. ( but still in the design stage) 
I do have an LX200. That prompted me to think in the direction of moving
the
primary, but still toying with the idea of sliding secondary.
There was a photo of the sliding secondary with the article. The unit
looked
quite rigid and well built. ( lots of adjusting screws to help colimate)

My main question was I guess, how does this perform when you are moving
the secondary in the light cone? is your secondary going to be a little
oversize?


Dave wrote
> It is considerably more difficult
>to construct than a rack and pinion or Crayford, it's heavier, and a
little
>more difficult to collimate, but the advantages completely overwhelm these
>issues.

what type of scope is it best suited to, to achieve these overwhelming
advantages ( big or small mirror, fast or slow focal ratio ) or doesn't it
matter?


andy