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

["Bobby Middleton" <bobm@koyote.com>]

----- Original Message -----
From: "Walter Koprolin" <a9125657@unet.univie.ac.at>

Hi Walter.
> I am in search for a decent coma corrector for a 10" f/4.72 Newt which
> will be dedicated for 35mm astrophotography.>
> The Vixen coma corrector is larger (does anyone know the free aperture and
> outside diameter?),

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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