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Re: [APML] RE: September Images
Thanks to all who responded to my mail.
M16 image:
Tracking: Glenn, I'm using a Giant Easy Guider and the pick off mirror is
before the reducer lens, so I am guiding at f/10 @ 2800mm so the
tracking is better then what was calculated. I also thought I read somewhere
that the reducing lens helps with the image quality (helps reduce field
curvature or something like that).
Collimation: Kolovso, I recently installed a Losmandy Side by Side
mounting plate and removed my equipment several times to get
the two scopes aligned. I forgot to recheck the collimation on the SCT so I
will definitely check it tonight (if its clear).
Its also possible that I got sloppy with my focusing on this shot but I
ruled that out do to the fact "I don't make mistakes" <g>
IC1805:
Jeff, I am still learning how to keep the level histograms correct on my
images and I wish Jerry Lodriguss will finish his new book soon. I hope
it can correct some of my image processing problems.
Thanks, Joe Schaefer.
----- Original Message -----
From: Glenn Ray <glennlray@mail.ev1.net>
To: <astro-photo@seds.org>
Sent: Sunday, October 06, 2002 1:30 AM
Subject: [APML] RE: September Images
> Joe Schafer wrote:
>
> This image to me looks out of focus or something's wrong with it, but I
can't figure it out. Any suggestion? I use the STI knife edge focuser but on
the SCT it's not as easy to use.
> http://www.starfillednights.com/image_data/M16_image_data.htm
>
> ------------------
> Well, it definitely shows signs of coma, but it looks more like an
out-of-focus refractor image rather than one for an SCT. I would have
expected to see donut-holes instead.
>
> Have you examined the slide (under high power) to see if the image appears
out of focus? If not, I'd suspect the scanner (although I can't recall
seeing a scanner produce coma like that).
>
> You also mentioned that you had A3-A4 errors w/ the ST-4. This would
equate to 2.0-2.7 arcseconds error (@ 1825 mm) which is borderline
acceptable for that focal length. That may also be a factor.
>
> Glenn Ray
>
>
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