Re: [APML] Clusters for review

["Jim Janusz" <jjanusz@dc.rr.com>]

Hi Frank,

My guess is that you have two issues here.  One is a hair or other type of
dust caused the prominence by Merope and the other, which you identified, is
a first surface reflection from glass near the focal plane, such as a filter
or focal reducer.  This is usually caused by coating problems.

Nice work.

Jim


----- Original Message -----
From: "Frank Barrett" <frankb02@bellsouth.net>
To: <astro-photo@seds.org>
Sent: Sunday, February 02, 2003 11:47 AM
Subject: [APML] Clusters for review


> OK, after many hours of experimentation I think I'm finally starting to
> 'get' this antivignetting stuff.  Here's a couple of images for your
review
> and comment.  Both had serious vignetting, the worse of which was cropped
> out.
>
> The Double Cluster: http://bellsouthpwp.net/f/r/frankb02/DblClstr.html
> The Pleiades: http://bellsouthpwp.net/f/r/frankb02/M45.html
>
> To see how much my setup is vignetting look here:
> http://bellsouthpwp.net/f/r/frankb02/M45-60m.jpg
> That's the raw image and was not processed in any way, just resized and
> converted to jpeg.
>
> There's an arifact that looks like a huge prominence extending from Merope
> that I didn't remove in Photoshop till I got confirmation from this list
as
> to its cause...I'm guessing this is a reflection from the f/6.3 focal
> reducer?  There's also a ring around Alcyone, but that one's not as
> distracting.
>
> How am I doing and what can I do to improve?  Thanks bunches.
>
> Carpe Noctem,  Frank
>
> Astropix:  http://bellsouthpwp.net/f/r/frankb02/astropix.html
>
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