Re: [APML] A long time lurker - Finally sharing some of my astrophotos...

[Matt BenDaniel <matt@starmatt.com>]

In a message dated 10/8/2001 10:11:39 PM Pacific Daylight Time,
mgreger@dashmail.net writes: 

I am most proud of some of my more recent images taken at the 2001
Oregon Star Party: 
  
http://rc1s3p9.dashmail.net/~mgreger/astro/gallery/Deepsky/Messier/M27/M27-2350mm/index.html 

--

I would be interested to know what is the cause of the faint blue ghost
images of the stars on the periphery of the image. You
have listed that it is a prime focus shot. I would have thought that it
might be due to some telecompressor optic or field flattener
glass just before the film plane. 

Roland Christen 

--

The C9.25 is supposed to have a flatter field than other Celestron/Meade
SCTs.  Has anyone seen similar ghosting problems with the C9.25?  The
film used (Provia 400F) has decent response out to 400nm.  Maybe the
C9.25 has some chromatic aberration in the corrector in the near-UV. 
Michael's image seems nicely focused.  I notice Celestron's web site
claims many advantages for their SCT designs, but they do not list
apochromatic (or even achromatic) among them.

BTW John Boudreau and others have said that 400F is a good film for some
objects, and I think this is a good example.  Looks a little less
sensitive to red, but that's OK with this object.  And it's available in
120.
-- 
Matt BenDaniel
http://starmatt.com

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