Re: First images with AP1200 GTO



I have SBIG's standard CLRGB filters and I do not experience such a
problem. I image a lot of clusters (ie. lots of starry fields) and I
have never encountered such a problem not even once.

Is it possible that slight ambient temperature changes are affecting
your focus point, thus giving you the false impression that the
filters are doing something? I amvery careful of the ambient
temperature and do refocus if necessary.


--- In ap-gto@..., "Rick Wiggins" <rickwiggins@...> wrote:

Hi Guys,
It is well known (meaning I personally know more than ten imagers
that have had this problem and it is regularly discussed on several
imaging forums) that the blue and green filters cause halos in RGB
images. Many people believe that they are very bad in the AstronDon
filters. They definetly happen with the AstroDons. I don't have
enough data on non-AstroDon filters to do an objective comparison.
It is obviously more prevalent around bright stars and is worse the
more you stretch the image. I have not seen halos with narrow band
filters of any brand.
Thanks, Rick

--- In ap-gto@..., chris1011@ wrote:

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

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.


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