Re: [APML] NGC 2392 revisited

["John Boudreau" <jeboud@mediaone.net>]

>
> Both are very nice John.  When you say on your web page that this is a
> "stacked combination of 30, 45 and 60 minute exposures", do you mean that
> you added all of the exposures to increase the effective exposure time?
>
> Best Regards,
>
> Dean Jacobsen


Thanks Dean. Film exposure lengths don't total up like CCD exposure times
do. If anything they just average out. The big advantage is stacking
smoothes out the grain in the final result, and also allows more digital
processing with out "blowing out" the subject.

It's usually best to stack exposure of similar exposure times, but since
this subject is seldom photographed and I was still unsure of the best
exposure for NGC2392 with the 400F film, I varied the exposure lengths from
30 to 60 minutes. Turns out that about 50 minutes would probably be best for
this subject and film @ f/11. This is a fairly bright object, and exposures
aren't dependant on the sky fog limit, just it's surface brightness.

John Boudreau
jeboud@mediaone.net
http://people.ne.mediaone.net/jeboud/astro.htm

----- Original Message -----
From: Dean Jacobsen <deanjacobsen@earthlink.net>
To: <astro-photo@seds.org>
Sent: Tuesday, January 01, 2002 9:50 PM
Subject: Re: [APML] NGC 2392 revisited



>
> Both are very nice John.  When you say on your web page that this is a
> "stacked combination of 30, 45 and 60 minute exposures", do you mean that
> you added all of the exposures to increase the effective exposure time?
>
> Best Regards,
>
> Dean Jacobsen
> www.astrophoto.net
> deanjacobsen@adelphia.net
>



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