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Re: [APML] coma/film-flatness?
It's coma. Field curvature isn't very noticeable with one of those 102mm f/9 Vixen refractors, so it isn't contributing much to the problem.
I believe Vixen still makes a focal reducer for this scope that should cure this, at the expense of some vignetting.
John Boudreau
http://home.attbi.com/~jeboud/astro.htm
----- Original Message -----
From: "Jeff Crilly" <jlcphoto@myrealbox.com>
To: "apml Astrophotography" <astro-photo@seds.org>
Sent: Tuesday, June 10, 2003 5:52 PM
Subject: [APML] coma/film-flatness?
>
> I just want to ask oh wise apml'ers for a confirmation that indeed this is
> coma on this picture and not 35mm film flatness issues, or some other problem...
>
> http://fototime.com/950EFD3E5310F34/orig.jpg
>
> Thats a picture of the lagoon. 30 minutes on provia 400f.
>
> The stars in the center are round, but at the edge of the image they are all comets,
> "pointing" away from the center (i.e. comet tails go to the center).
>
> The scope is a mid-80s C102F - 102mm flourite refractor from celstron/vixen.
>
> The camera is a Nikon EM.
>
> The mount is G11. I polar aligned and checked the drift just before the shot.
>
> thanks
>
> jeff
>
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