Star Halo(s)

[Kaliska]

I'm getting these halos from a few of my filters.

Anything I should be doing to get rid of them?

[symmetal]

If you're using ZWO narrowband filters then this thread may help you out. OIII seems to be the worst offender.

Alan

[Kaliska]

No, I'm using the 36mm Baader filters.

And i'm getting them on all the NB filters.

[ebdons]

Hi, what cam are you using and gain etc or on auto, I get them on my sx825 mono which maybe sensitive when using with a F6 and shorter scope and only when using an astronomic UHC with or without a ir cut addon. maybe help?

[Kaliska]

I've got the ASI1600 MM Cool (Gain 139, Offset 21, Unity Gain) with the TSQ100 F5.8

[ebdons]

Hi it maybe a bad filter tho unlikely, f5.8 maybe but I don't always get them depending on the exp time and manual gain and offset, astronomic UHC used to have a issue with halos etc, but that was a few years ago now, and I don't get halos with any other filter bar the UHC, it  could be the ZWO has an issue with sensitivity or has gone "hyper-sensitive" like my QHY10 and they are sending me a replacement as they failed to fix it. maybe an issue with the cooling temp? somebody on here will now  hopefully?

[ollypenrice]

I would send some sample images to Baader Planetarium stating the scope's focal length, focal ratio and the pixel size of the camera.

I'd also send the same to the camera supplier.

Olly

[Adam J]

On 08/11/2018 at 23:51, Kaliska said:

I'm getting these halos from a few of my filters.

Anything I should be doing to get rid of them?

What star is that and what exposure length? Can I see the full image? 

[Kaliska]

Sorry for not replying, but I've had somewhat of a disaster here. The external HD where i download ALL of my data (everything) was dropped accidentally while it was writing my latest batch of files and has subsequently stopped working ? I'm now in the process of having the HD sent away for analysis to see if it can be recovered.

Fingers crossed.

[symmetal]

Sorry to hear about your misfortune Kaliska.  Hope it can be recovered. I suppose now's not the time to give advice about backup disks.

Alan

[Kaliska]

Well, its good news... All data has been saved and recovered and all done for £100, which included a new 1TB USB3 Hard Drive (not too bad I thought).

So, back to my problem with my filters :(

I've attached a single 180sec HA sub of the Horse Head taken last night and it looks pretty bad :(

[Kaliska]

Just had this sent to me from Baader, more of less saying is the reflections of my equipment, rather than their filters.

https://www.baader-planetarium.com/en/downloads/dl/file/id/287/product/2996/faq_problems_with_filters_can_have_the_strangest_causes.pdf

[spillage]

Have you contacted zwo. Sean there is very helpful.

[ollypenrice]

1 hour ago, Kaliska said:

Just had this sent to me from Baader, more of less saying is the reflections of my equipment, rather than their filters.

https://www.baader-planetarium.com/en/downloads/dl/file/id/287/product/2996/faq_problems_with_filters_can_have_the_strangest_causes.pdf

Baader are very knowledgeable about optics. They are not just retailers but optical designers so I'd take their reply seriously, especially as the camera is getting a reputation for this problem.

It is rare not to have problems with Alnitak. I've only used one setup out of many which didn't throw up problems. One processing fix would be like this: 

Ps Curves. Put cursor on background just outside halo and Ctrl Click. This puts a fixing point at the background sky level. Put another fixing point below that.

Pull down the Curve above the upper fixing point and restore it higher up. Careful shaping of the curve will give a fairly natural result. This is just from a screen grab of your original halo.

Olly

 

[Rodd]

18 minutes ago, ollypenrice said:

Baader are very knowledgeable about optics. They are not just retailers but optical designers so I'd take their reply seriously, especially as the camera is getting a reputation for this problem.

It is rare not to have problems with Alnitak. I've only used one setup out of many which didn't throw up problems. One processing fix would be like this: 

Ps Curves. Put cursor on background just outside halo and Ctrl Click. This puts a fixing point at the background sky level. Put another fixing point below that.

Pull down the Curve above the upper fixing point and restore it higher up. Careful shaping of the curve will give a fairly natural result. This is just from a screen grab of your original halo.

Olly

 

Wow Olly--I never knew what you meant by "put a fixing point at the background".  I had no idea that you meant to click on the background in a certain area and proceed from there as you describe.  I would have never thought this as PI does not work like this-- nowhere near.   Very interesting.  I am beginning to see that PS could be a very useful ancillary tool for me.  If I had room on my computer and if I could learn how to use it.

regarding the ASI 1600 and halos.  I have seen none in narrowband. I have seen some halos in the blue part of the spectrum, but not many--only on very bright stars.  I have not been feeling bad about it.  Curses if I start to now! ?

Rodd

[ollypenrice]

1 minute ago, Rodd said:

 I am beginning to see that PS could be a very useful ancillary tool for me. 

 

Do it!!!!

?lly

[Kaliska]

1 hour ago, ollypenrice said:

One processing fix would be like this: 

Now that is impressive! I have PI, but now thinking that PS might be my only answer. There are PI routines to dampen down the halos, but I've yet to try them.

[ollypenrice]

8 minutes ago, Kaliska said:

Now that is impressive! I have PI, but now thinking that PS might be my only answer. There are PI routines to dampen down the halos, but I've yet to try them.

Photoshop didn't get to be where it is in the marketplace by accident. I'm no fan of Adobe as a company but Photoshop is a work of genius, particularly in terms of the user interface which creates analogue ways of doing mathematical processing.

Olly

[Kaliska]

@ollypenrice Do you do everything in PS or just certain processing techniques?

[ollypenrice]

13 hours ago, Kaliska said:

@ollypenrice Do you do everything in PS or just certain processing techniques?

Almost everything in Ps, but what I do in PI is important. My linear RGB always goes into PI for DBE to remove gradients and for SCNR green. Sometimes I run Lum through DBE but mostly it's OK from our dark site.

Sometimes I use PI's colour calibration and I like the photometric version of that.

Later on I may try PI's Local Histogram Equalization but I generally prefer Noels Actions Local Contrast Enhancement.

The rest - colour intensification, adding L to RGB, adding Ha to red and OIII to green and blue, sharpening, noise reduction, cosmetic repairs etc is all Photoshop. Almost everything is done as a bottom layer, the modifications selected by erasing parts of the unmodified top layer.

The other software I use all the time is Registar. If I crop a filter's image I can quickly make all the others fit it etc. I also use it for mosaics and for adding high res inserts into widefields.

Olly

[pietervdv]

Kaliska,

Sounds familiar, I too seem to be having some halos around bright stars with my asi1600. The halos were not an issue with my previous camera (an old sbig st8300). I am using an Astrodon 5nm HA filter. Ever since I made the switch from the 8300 CCD to the asi, it started. There are not that huge, but quite annoying.

I read somewhere it has to do with the cover or sensor glass in front of the CMOS that is not AR coated, but I cannot recollect all the details.

Pieter

[Adam J]

On 04/12/2018 at 14:20, Kaliska said:

Just had this sent to me from Baader, more of less saying is the reflections of my equipment, rather than their filters.

https://www.baader-planetarium.com/en/downloads/dl/file/id/287/product/2996/faq_problems_with_filters_can_have_the_strangest_causes.pdf

Stupid question, but I see this lots more when people use un mounted filters in comparison to mounted filters. The reason being that you are physically able to mount the filter the wrong way around. So have you tried reversing the filters in the wheel?

I don't have any reflections at all with my Astrodon 5nm filters and my ASI1600mm pro. Even the micorlens diffraction effect is lesser than in most images. 

The other thing to try is imaging the same star without the corrector. 

 

[david_taurus83]

5 hours ago, Adam J said:

Stupid question, but I see this lots more when people use un mounted filters in comparison to mounted filters. The reason being that you are physically able to mount the filter the wrong way around. So have you tried reversing the filters in the wheel?

I don't have any reflections at all with my Astrodon 5nm filters and my ASI1600mm pro. Even the micorlens diffraction effect is lesser than in most images. 

The other thing to try is imaging the same star without the corrector. 

 

I have the 36mm unmounted. I noticed when fitting the narrowband that there was a silver sheen on one side and more red on the other. I thought the Baader could be mounted either way. How can you tell which way round they all go? I've not had a chance to try out the 3 narrowband yet either.

Is this correct  @FLO

[david_taurus83]

I think I found an answer. Looks like I'm opening the filter wheel then!

https://www.baader-planetarium.com/en/blog/unmounted-filters-which-side-should-face-the-telescope/

 

[david_taurus83]

As the above link, Baader do indeed pencil an arrow onto the sides of the filter indicating to face towards the scope. All mine are marked, LRGB Ha OIII and SII. Out of 7, I had 5 the wrong way round!