Re: [APML] Coma Corrector for 10" f/4.72 Newton

[Walter Koprolin <a9125657@unet.univie.ac.at>]

Hi Bobby,

Thank you for the reply. So, both the Vixen and the Lumicon coma
correctors seem to be interesting options. Does anyone have the
measurements of these correctors (diameter/length)? I need them to specify
the focusser I will need.

I want to guide the Newton, which will be custom-made and (hopefully)
very rigid, with a guide scope mounted side-by-side. I hope to minimize
vignetting by not using a T-mount, but a custom-made adapter for my Nikon
F3, and a secondary mirror of suitable size.

Thanks again,

   Walter Koprolin
   Astrophoto-Gallery, Observation Reports, Telescope Testing:
   http://www.astro.univie.ac.at/~koprolin/


> Hi Walter.
>
> I used the Vixen coma corrector for my f/4.25 homebuilt 8" newt. I can't
> remember its clear apreture but it was the largest corrector availiable. It
> would require the direct-wide adaptor and also a special OAG that would hold
> it plus a custom machined adaptor to fit it to the OAG . I was able to use a
> 2.7" Lumicon OAG that was once availiable but you probably won't be able to
> find one of these now.
> The Vixen corretor was designed for an f/4 system. For my f/4.25 it had good
> correction. Would correction be satisfactory at f/4.7? I don't know.
> The alternative is the Lumicon corrector which is designed for a f/4.5
> system. You should be able to find a used one. It fits into Lumicon's Newt
> ez guider and you probably could find one of these too. You will have some
> vignetting. It won't be objectionable except right at the corners but this
> might be the most practical solution.
> Vignetting and uneven illumination of fast mirrored systems is one of their
> design realities (along with the need for correction). The only way around
> this vignetting is to use expensive custom accessories and after all that
> the T mount of your 35mm camera will cause vignetting also.
> Bobby Middleton
>
>
> I read, and takes a special direct-wide photo adaptor,
> > but will it work for my f/4.72 system? It is built for the R200SS, which
> > is f/4. I also came across a Lumicon model, but found no additional data
> > on that one.
> >
> > I am looking for pin-point stars and no vignetting out to the edges of
> > 35mm format. Any ideas?
> >
> > Thanks in advance for your help,
> >
> >   Walter Koprolin
> >   Astrophoto-Gallery, Observation Reports, Telescope Testing:
> >   http://www.astro.univie.ac.at/~koprolin/
> >
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