Register    Login    Forum    Search    FAQ

Board index » Products » Cameras




Post new topic Reply to topic  [ 23 posts ]  Go to page 1, 2, 3  Next
Author Message
 Post Posted: Fri Oct 20, 2017 10:05 am 
Offline

Joined: Sat Jul 01, 2017 8:58 pm
Posts: 10
Hello,

Two days ago I integrated IC 443 in H alpha - after stacking the frames a bright halo / reflexion of my f/4 Newton's mirror was visible around a bright star next to IC 443.

So yesterday, I took for every filter (R G B L Ha OIII SII - all ZWO filters) a 4min test exposure of beta And (2,1mag) and the halo appeared more or less with every filter. Moreover, even other symmetrical patterns and rings are visible. In case of SII the main reflexion is visible faintly several times throughout the whole field!

See here: Image

So what is this and how can it be fixed? It simply ruins all images with bright stars?!

Cheers, Stephan


Top 
 Profile  
Reply with quote  
 Post Posted: Sun Oct 22, 2017 8:47 pm 
Offline

Joined: Tue Oct 17, 2017 11:55 am
Posts: 12
Same problem for me and also other people with ZWO filters. I have these terrible reflections even on mag 7,5 stars on f/5,6 scope :(


Top 
 Profile  
Reply with quote  
 Post Posted: Mon Oct 23, 2017 2:18 pm 
Offline

Joined: Sat Jul 01, 2017 8:58 pm
Posts: 10
dansemacabre wrote:
Same problem for me and also other people with ZWO filters. I have these terrible reflections even on mag 7,5 stars on f/5,6 scope :(


So it is known as a filter problem? Would be replacing the filters with e.g. Baader filters solve the issue?


Top 
 Profile  
Reply with quote  
 Post Posted: Mon Oct 23, 2017 4:51 pm 
Offline

Joined: Tue Mar 21, 2017 7:55 pm
Posts: 10
[/attachment]
Attachment:
Halos.jpg
Halos.jpg [ 106.19 KiB | Viewed 569 times ]
I'm having the same problem. I using a 10" Truss Tube RC @f6. It shows up more on the narrow bands and is not there without a filter.
Also the star is off center like I'm out of collimation, but it's position shifts with different filters. Maybe the filters aren't laying flat in
the filter wheel? I looked back at some older shots I took with an 8" steel tube RC @f6 and I don't see the halos.
Dave


Top 
 Profile  
Reply with quote  
 Post Posted: Tue Oct 24, 2017 3:44 pm 
Offline

Joined: Tue Oct 17, 2017 11:55 am
Posts: 12
schurig wrote:
So it is known as a filter problem? Would be replacing the filters with e.g. Baader filters solve the issue?

I can't say "its a known problem", I'm just saying that in my experience and experience of my friends using same filters, ZWO narrowband filters makes this kind of reflection. For me particullary, reflection with OIII/SII filters is present for 7,5mag stars on f/5,6 scope! LRGB seems to be OK for me, Ha has SOME reflection, but not as huge as SIII or OII. I'm still not sure if its common problem with ZWO narrowband filters, or just my bad luck with particular pieces. As far as I discussed it and compare pictures of same objects: Astronomic/Baader has reflections too, but not such terrible as these. Which is sad for ZWO as they cost the same price :(


Top 
 Profile  
Reply with quote  
 Post Posted: Wed Oct 25, 2017 9:19 am 
Offline
User avatar

Joined: Thu Feb 21, 2013 2:51 am
Posts: 2292
did you try change the face of the filter?

_________________
ZWO Founder
Location:lon=120.6 lat=31.3
SuZhou China


Top 
 Profile  
Reply with quote  
 Post Posted: Wed Oct 25, 2017 4:56 pm 
Offline

Joined: Tue Mar 21, 2017 7:55 pm
Posts: 10
Quote:
did you try change the face of the filter?


I assume you mean turn the filter over. I will try that. I did change the spacing between the filter and the CMOS
and it may have made a slight difference, but still there. I will turn them over today and report back tomorrow.

Dave


Top 
 Profile  
Reply with quote  
 Post Posted: Fri Oct 27, 2017 12:26 am 
Offline

Joined: Tue Mar 21, 2017 7:55 pm
Posts: 10
I turned over my narrowband filters and shot some images, but I can't see any difference. It's really evident on bright stars
during long exposures and even shows up on some not so bright stars in those exposures. I can't afford new filters at this time,
so I'm just going to live with it unless someone finds another solution. Otherwise, I really like the camera (ASI 1200mm cool).
I attached a pic of the bubble, if you look at the brighter star below and left of center, you can see the halo.
Good luck to us all.

Dave

Attachment:
Bubble New Final XS.jpg
Bubble New Final XS.jpg [ 153.19 KiB | Viewed 488 times ]


Top 
 Profile  
Reply with quote  
 Post Posted: Fri Oct 27, 2017 6:55 am 
Offline

Joined: Sat Jul 01, 2017 8:58 pm
Posts: 10
davebl wrote:
I turned over my narrowband filters and shot some images, but I can't see any difference. It's really evident on bright stars
during long exposures and even shows up on some not so bright stars in those exposures. I can't afford new filters at this time,
so I'm just going to live with it unless someone finds another solution. Otherwise, I really like the camera (ASI 1200mm cool).
I attached a pic of the bubble, if you look at the brighter star below and left of center, you can see the halo.
Good luck to us all.

Dave

Attachment:
Bubble New Final XS.jpg


Dave, thanks for you tests last night. I wish I could contribute some tests as well, but here in Germany it has been cloudy and rainy for more than two weeks now :-(

The reflection (the one that is about twice the star diameter) I see in your image is tolerable for me. I see such kind of reflection in many narrowband images around bright stars. But I'm totally at odds with the big reflections around the stars (multiple times bigger in diameter than the star diameter) as seen in my first postings (visible not only in narrowband but e.g. also in R channel). So if you have the opportunity to make one more test... then try to take a pic without any filter. Because I still don't know if the filters is the problem or the protection window of the chip.

Thanks, Stephan


Top 
 Profile  
Reply with quote  
 Post Posted: Fri Oct 27, 2017 6:55 pm 
Offline

Joined: Tue Mar 21, 2017 7:55 pm
Posts: 10
Hey Stephan,

I actually did take an image without a filter inline and the star looked perfect, no hint of a halo. One thing I did
notice last night was after turning the filters over there was a huge bright halo that appears to be bad vignetting except
the corners are still dark. I didn't really catch it the 1st night as I thought maybe I was having an issue with dew. So I
Turned the filters back over last night and will test tonight. The halo appears on the OIII and SII filters. I'll post some pics
tonight or tomorrow.
I seem to have a problem with tilt in my filters. I'm using the 31mm unmounted and they don't set flush in the wheel and
the washers that hold them in are at an angle to make up for it. Seems like they should fit flush with the wheel. It makes it
difficult to get even tension on the filters. If you tighten one screw a little too much you can actually see the filter tilt.
Anyone else notice this?

Dave


Top 
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
 
Post new topic Reply to topic  [ 23 posts ]  Go to page 1, 2, 3  Next

Board index » Products » Cameras


Who is online

Users browsing this forum: No registered users and 11 guests

 
 

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to: