How do I prevent halo around stars?

lanties

My Imaging train is as follows:

Skywatcher Esprit 100 -> Esprit 100 Flattener -> ZWO OAG - > ZWO Filter Wheel -> ZWO 31mm filter kit -> ZWO 1600MM-Cool. The back focus is exactly 63mm as per the recommendation of the flattener

Running_Chicken_in_Ha_15_x_600_Second_Subs-e1523819692411.jpg

Apologies the file name is wrong. It is actually 15x300 second subs in Ha.

Please note the halos around the brighter stars. I get this with my other filters as well. Some more and some less prominent.

What am I doing wrong and how do I fix this? Your assistance will be much appreciated.

s3igell

1) Check that you mounted the Filters into the Wheel with the "Shiny Side" pointing toward the Scope (not the Camera).

2) Check Focus on each Filter (don't assume all Filters are Parfocal)

3) Check on Forums with Skywatcher users to see if your specific Flattener+Scope combo is known to cause Halos (usually only an issue with certain inexpensive Reducers like some of the SCT 0.63x units).

lanties

^^^ Thank you.

1. I think I may have had this wrong. I have flipped them all. I should be able to see tonight

2. Done

3. Done

Thank you for the advise

lanties

I have done some integration last night and the Halos are still there. Even after flipping the filters. I am attaching 4 images

1. Ha 30 x 300S stacked with Flats, Darks and BPM

IC2944_30x300S_Flats_BPM_Darks_Flipped_Ha_Filter.jpg

2. S2 1 x 300S (Halo Prominent)

IC2944_1x300S_flipped_ZWO_filter_S2.jpg

3. O3 1 x 300S (Halo Prominent)

IC2944_1x300S_flipped_ZWO_filter_O3.jpg

4. No filter 1 x 300S ( Focussing was not perfect on this but there is no halo)

(Could not add this due to limitation)

In the stacked Ha image there is also a glow at the bottom right that seems to be artificially introduced. I am using USB3 to connect the camera to the computer.

Please advise what else I can try to get rid of the Halo's and Glow

lanties

After reading a 100's of pages of forum posts, it appears that this is a known issue with ZWO filters and that there apparently is a work around that will assist in minimizing the halo problem.

May I please have more information regarding the filter masks for 31mm unmounted filters please?

Support@ZWO

Hi there

Sorry to say the halo is cause by filters, it's normal for ZWO Ha filters. We are working on it, next generation of ZWO narrowband filters will have less halo.