IC434 - Reflections - Artemis 285CCD

[1275rob]

Dear All,
This is my first attempt with IC434 Horse head Nebula and I am having problems with reflections. I have  seen it in other images but this is one of the most effected because of Alnitak.
In measuring the halos it point to CCD internal from the CCD and possibly the CCD chamber window.
There is a slight chance that there may of been a little due on the lens at one point but it looked clear when checking just before shutting up shop for the night.
Looked at various methods of processing with PS and Iris to removing the halo but very very time consuming.
If any one has any ideas would be interested in hearing them.
Otherwise will just have to live with it.
Image was taken with an Artemis 285CCD 40x120sec subs with a Lumicon Deep Sky filter.
Happy New Year.
Regards,
Bob.

[Kinch]

Sorry I did not reply earlier - have not looked in here in a while....

I had the same problem re a halo but I am pretty sure it was my Ha 6nm filter that caused this. I did a test for the filter manufacturer (as I had asked them about the problem.....not sorted yet by the way) and when they had me use two filters in the optical path  (Luminance as well as the Ha filter) it certainly reduced the halo. Not a good final solution as it was very awkward for me to use two filters in line and that will not work for my normal set-up.

........just wondering if perhaps the halo in your shot was also caused by the filter???
Have you tried the same subject without that particular filter?
Kinch

[1275rob]

Hello Kinch,
Thanks for the reply. I am afraid I only just picked up your reply.
I did a test without a filter and the reflection was still there.
On taking measurements it worked out that it is the chamber clear window.
I have a new high transmission glass to fit as a replacement but not had chance to fit it yet.
Hopefully this will help the problem.
The fitting of a second filter is interesting and I will see if I can try this idea.
Many thanks.
Bob.