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Re: [APML] The Veil...
Hi Don,
As Chuck has said, it certainly looks like the shot is out of focus. The same for your M8-20 shot posted earlier.
I'm guessing that you're not using a field flattener with the scope--- this is a 120mm f/5 refractor? If so, it's got strong field curvature. The "rotated" looking stars would just then be due to off-axis aberrations. Short of finding a field flattener for it, the best you can do for it is to knife-edge focus near center, and just use the scope knowing that you'll have to crop away the outer section of each shot.
BTW--- A dry air or nitrogen purge is still a good idea in damp conditions. I use a dry air purge based on Herm's system. But I doubt it would have made a noticable difference in these shots.
John Boudreau
http://home.attbi.com/~jeboud/astro.htm
----- Original Message -----
From: "Don Spencer" <ecdon@cox.net>
To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
Sent: Friday, May 30, 2003 3:37 AM
Subject: [APML] The Veil...
> Hi All,
> I just finished processing my first attempt at shooting the Veil.
> http://members.cox.net/ecdon/veil.html
> You'll notice in this shot that the center seems a bit out of focus, the
> edges focused real well, but somewhat rotated. This is the second shot from
> that night that has this appearance, which leads me to believe that dew was
> the culprit(it formed earlier and stayed longer the 2nd night I was out). By
> comparison, my M8/M20 photo shows slight curving at the edges and dew was
> just starting to pick up at the time the photo was shot. I also learned a
> valuable lesson...it is better to take multiple shots of one area, stack
> them, and get a quality photo, than it is to spend 2 nights shooting 1 shot
> of anything in site! I am battling noise in both my Antares region and
> IC4592 shots.
> Thanks,
> Don Spencer
>
>
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