Re: [APML] New Image: M46 and NGC 2438 and a question

["John Boudreau" <jeboud@attbi.com>]

 > Hello all,
> Another image from Camp Sorrow (this is our nickname for our camp in
> Chiefland, FL- it indicates our weather conditions).  This was shot
> through the ever-present haze.  My question is:  is there any reflection
> nebulosity around M47?  I don't know if it is haze or reflection, but I
> have some blue around this group of stars.  Thanks for any help.
>
> http://www.astro-photography.com/m46.htm
>
> Jeff Ball



Hi Jeff,

First of all nice shot! Bummer about the field rotation though.

I looked at your image in PS. The "blue look" in and around the cluster
appears to be mainly due to slightly misaligned color channels showing up
around each star, probably due to atmospheric refraction. The blue channel
is the worst offender here. Fuji 400F's strong blue sensitivity can really
show this problem up, along with any chromatic aberrations from the optical
system.

If you realigned the color channels, especially the blue, the majority of
this blue cast in the cluster would disappear. I did an RGB channel
realignment in RegiStar on your image and the improvement was noticeable. If
you have RegiStar, have a look at: http://home.attbi.com/~jeboud/xchrom.htm

This works well on atmospheric refraction problems, along with the lateral
color problems I originally intended the article for.



John Boudreau
jeboud@attbi.com
http://home.attbi.com/~jeboud/astro.htm



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