Strange halos

[Phillyo]

Afternoon all,

Since I bought the new Antlia 5nm ALP-T Dual Band filter, I've been seeing these strange halo's around some stars. They aren't the brightest stars in the image by any stretch of the imagination, and I don't think they're caused by reflections. They weren't there with the IDAS NBX filter, nor are they there with the normal UV/IR filter. 

Any idea what might be causing them? Do I need to send the filter back?

Thanks in advance.

[Shibby]

Can you post a full frame of these two images? To me (certainly the second image) it looks like the halo could actually be an internal reflection of the bright star, not the star that happens to coincide with the halo.

Edited January 18, 2022 by Shibby

[Phillyo]

On 18/01/2022 at 15:29, Shibby said:

Can you post a full frame of these two images? To me (certainly the second image) it looks like the halo could actually be an internal reflection of the bright star, not the star that happens to coincide with the halo.

Hi, yeah I'll post it up later after work. Thanks

[Phillyo]

On 18/01/2022 at 15:29, Shibby said:

Can you post a full frame of these two images? To me (certainly the second image) it looks like the halo could actually be an internal reflection of the bright star, not the star that happens to coincide with the halo.

The more obvious one is top middle. Second, less obvious, is left of the frame just above and left of horse head. This is just a simple stretch and save so the file isn't the best but you can hopefully see where they are.

[inFINNity Deck]

I can see them both and wonder what your flats look like. Did you make and apply any? If you made them, could you post the master flat here?

Nicolàs

PS: nice image!

[Phillyo]

23 hours ago, inFINNity Deck said:

I can see them both and wonder what your flats look like. Did you make and apply any? If you made them, could you post the master flat here?

Nicolàs

PS: nice image!

Master flat below. I don't often use flats as it doesn't change much. Same with darks most of the time.

[inFINNity Deck]

that looks very clean, no issues there then.

Nicolàs

[Phillyo]

6 hours ago, inFINNity Deck said:

that looks very clean, no issues there then.

Nicolàs

Yeah this is what's confusing me. No idea what's causing them.

[Clarkey]

Looking at the positions of the halos relative to the stars, the stars do not even appear to be centred. This suggests something other than standard internal reflections. Do they appear on all the subs?

Another thing to try is to rotate the filter (or camera) to see if they move. If they do, it suggests a filter issue.

Definitely an odd one though.🤔