Roland, the SBIG filters are from Custom Scientific I believe. I get very strong halos from my green Astrodon. I had thought it was due to the fast f-ratio I was shooting with the scope I've had till now.

Stuart
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From: chris1011@aol.com
Date: 2007/06/21 Thu PM 02:37:23 EDT
To: ap-gto@yahoogroups.com
Subject: Re: [ap-gto] Re: First images with AP1200 GTO

In a message dated 6/21/2007 12:38:25 PM Central Daylight Time,
kgkirkley@aol.com writes:

you say the Baader filter(s?) do
not cause any halos.

I have been testing the Baader filters for the last week under all kinds of
sky conditions. I do not see any halos around any bright stars. My H-a images
are very sharp with no reflections or ghost images around any stars. Maybe I am
mistaken about Astrodon filters (I have not tested them myself, but go only
on what I have heard from others). I do know that several of my RGB filters in
my ST10 camera cause multiple reflection ghosts near bright stars. I don't
know who makes these filters for SBIG, but they are not of the quality level of
the Baader series. In my STL11K camera I have installed 3 of the narrow band 2"
Baader filters and the images they produce are super nice. All Baader filters
have high grade multi-layer coatings on them to insure freedom from
reflections.

It may also be that the original poster's reflections are coming from his
cover glass and filter rear surface, something that can't be avoided unless the
coverglass is coated with a multi-layer.

Rolando


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