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Filters and halos, what is the answer?

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#26 DeanS

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Posted 01 September 2012 - 09:47 AM

I went thru a similar experience with filters. I was using gen 1 AstroDons with my ST2k and E160 and got some fairly bad reflections on brighter stars. This is a fast F/3.3 system and made the problem worse that when I used it on my C9.25 at F/5.8.

I got a set of new Baader filters and this did not solve my problem at all. I was very dissappointed and sent them back in to exchange for the newer Gen2 Astrodons.

Here is an image with the Baader.

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  • 5397887-M42cn.jpg


#27 DeanS

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Posted 01 September 2012 - 09:50 AM

And here is an image with the Gen2 Astrodons. Granted not the same object but plenty bright blue stars in this. Still see a small amount of reflections but I can live with it.

I think each optical system is going to be different. I suggest you have an agreement of exchange before you buy a new set.

Dean

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#28 alpal

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Posted 01 September 2012 - 09:50 AM

alpal: I am chep too, for my 50mm round I selected 5nm instead of 3nm because I am not able to spend $1000 on filter but I am able to spend $600. So my 1.25" are 3nm set and 50mm are 5nm set.

as I understand we are all on budgets, there's only Baader 7nm Ha filter that is very good and that I recommend for tight budget beginners. But for the other two emission lines there's unfortunatelly not much to choose from so I recommend to save money for at least 5nm Astrodons :) I also purchased one filter by one, not all in one order :)



Hi Pavel,
I now have a new Baader 7nm Ha filter.
I tried out my new CCD camera for the first time tonight.
I got it to focus on all 5 filters & download pics.
I didn't have any luck with guiding using Maxim DL & a Lodestar -
so at the moment I am trying to learn Maxim DL but it
is an extremely difficult program to use.
PHD guiding is so simple to use in comparison.

My problem is not filters - it's Maxim DL -
the most difficult program to use that I've ever seen in my life.

#29 freestar8n

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Posted 01 September 2012 - 12:16 PM

Hi-

Thanks for providing some example images. Can you describe the imaging setup in each case? Your second example does show a halo, but it is very large around the bottom star. As a halo gets bigger it starts to fade out - so just by changing a spacing you can make a small, visible halo become a large, faint halo.

What you're showing may really be due to an improvement in filter quality - but I would like to confirm the size of the halo matches something truly associated with the filter.

This thread has a mixture of LRGB and narrowband references - and multiple setups as people refine their equipment - so I would like to isolate and identify the filter as the true cause of halos as much as possible - and make sure the referenced filters are the latest "kind" after any fixes to a halo problem.

Many people, including me, use Astronomik 2c filters (the later version that "fixed" the halo problem they had earlier) along with Baader narrowband - and don't have problems with halos. So I think it's worth doing some investigation to find out why some people get halos and others don't.

Frank

#30 blueman

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Posted 01 September 2012 - 12:24 PM

Hi,
Yes, this photo demontrates the halos quite well. I had the same thing with these filters.

The Baader did the exact same thing, but only on the brightest stars, those with less magnitude did not display halos.

As to the cause of halos, well I am very aware of the articles that were written concerning cause and location of the offending surface. However, I went through a great deal of time with measurements and such with my ML8300 and FLI filters. The experts that were looking at my problem all agreed that the halos were the result of the CCD window for the most part. But some thought the CCD Slip Cover was the culprit but still others felt that it was internal reflection in the filter itself. Each was able to show the math that showed the distance from the CCD required to make the halo agreed with their opinion.
Interestingly, the one that turned out to be correct was the one person that said the 3mm distance was not from the CCD to the reflecting surface, but rather the 3mm represented the thickness of the glass of the filter and the reflection was from the two surfaces within the filter.
The reality check for all of this is simple. If the halo disappears when another filter is used, then the filter was the cause. For me this was the case.
Now if you have halos and new filters do not remove them, well then you have another source for the reflection. There can be many reflections shown in one image. Each halo being a different diameter due to the distance between the reflecting surfaces.
I did not write this thread to argue the cause of halos, but rather to report on the filter halos and what filters seem to be free of halos. So, if you do not agree with my assessment that is fine. :cool: I have done the work, spent the money and time to track down MY problem with halos and it was filters. :)
Blueman

I went thru a similar experience with filters. I was using gen 1 AstroDons with my ST2k and E160 and got some fairly bad reflections on brighter stars. This is a fast F/3.3 system and made the problem worse that when I used it on my C9.25 at F/5.8.

I got a set of new Baader filters and this did not solve my problem at all. I was very dissappointed and sent them back in to exchange for the newer Gen2 Astrodons.

Here is an image with the Baader.



#31 blueman

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Posted 01 September 2012 - 12:29 PM

Hi Frank,
When did you purchase your Astronomik 2c filters? Perhaps the filters that I had predated yours. But the filter the Baader sent to me for testing (Ha filter) was their newest version of their filter that was not yet available for sale. It was an improvement, but it was not free of halos.

I think it is great that the filters you have do not halo, so it would probably be a good thing to know when your filters were purchased, so those thinking about buying them might know what to look for with this brand.
Blueman

Hi-

Thanks for providing some example images. Can you describe the imaging setup in each case? Your second example does show a halo, but it is very large around the bottom star. As a halo gets bigger it starts to fade out - so just by changing a spacing you can make a small, visible halo become a large, faint halo.

What you're showing may really be due to an improvement in filter quality - but I would like to confirm the size of the halo matches something truly associated with the filter.

This thread has a mixture of LRGB and narrowband references - and multiple setups as people refine their equipment - so I would like to isolate and identify the filter as the true cause of halos as much as possible - and make sure the referenced filters are the latest "kind" after any fixes to a halo problem.

Many people, including me, use Astronomik 2c filters (the later version that "fixed" the halo problem they had earlier) along with Baader narrowband - and don't have problems with halos. So I think it's worth doing some investigation to find out why some people get halos and others don't.

Frank



#32 freestar8n

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Posted 01 September 2012 - 12:43 PM

Hi-

I don't know the actual date, but it was after the 2007-8 timeframe in which Astronomik addressed the issue some customers had with halos. They describe it here along with a ten year warranty on their filters.

It's not just me, for whom Baader and Astronomik filters don't halo. Many people are getting good results with them. That's why I'm trying to confirm that the people who do get halos can match the spacings and f/ratio to the filter itself. And for that I would need actual data and images with which to make my own assessment.

Frank

#33 blueman

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Posted 01 September 2012 - 01:34 PM

Hi Just for reference sake, I checked my records. My Astronomik filters were purchased about Jan 08 and the replacement Ha filter was sent to me 4-27-08 from Astonomik, it came from Germany direct to me. I purchased Baader filters after selling these 8-1-08 and then purchased the Astrodon Gen2 filters 1-12-09.
I can only state what I actually saw in my images. When I put the Astrodon filters in the wheel, I NEVER saw another halo with the ST-2000 camera. I sold the camera with filters and wheel a while back.
Then as I stated, I bought the ML8300 and FLI filters, then Baader filters and now again a set of Astrodon Gen2 filters and had the exact same experience.
Blueman

Hi-

I don't know the actual date, but it was after the 2007-8 timeframe in which Astronomik addressed the issue some customers had with halos. They describe it here along with a ten year warranty on their filters.

It's not just me, for whom Baader and Astronomik filters don't halo. Many people are getting good results with them. That's why I'm trying to confirm that the people who do get halos can match the spacings and f/ratio to the filter itself. And for that I would need actual data and images with which to make my own assessment.

Frank



#34 Gregk

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Posted 01 September 2012 - 01:41 PM

There is a good tutorial re:Replace color in photo shop
I have Gen I Astro Don so i know the drill. Fixing Problems I

Halo Removal here

#35 blueman

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Posted 01 September 2012 - 01:45 PM

Hi,
Unfortunately, I became quite good at removing halos. :tonofbricks:
;)
But! There are some cases where they just can not be removed without significant degredation of he image. M-45 or The Horse Head with Alnatak are good examples.
Blueman

There is a good tutorial re:Replace color in photo shop
I have Gen I Astro Don so i know the drill. Fixing Problems I

<a href="dg-imaging.astrodonhttp://flic.kr/p/cYhDU.com/tutorials/" target="_blank">Halo Removal here</a>



#36 DeanS

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Posted 01 September 2012 - 01:48 PM

I have used my ML8300 with 36mm astrodon filters on my E160 and do not get the halos or reflections. Did not even think about any other brand after my previous experience.

I have also used an SXV-H9 with old astronomik 2" filters and got bad halos.

I think the faster the system the more prone the halos??

Dean

#37 blueman

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Posted 01 September 2012 - 02:34 PM

HI,
The speed would probably be a factor, I image a f/5.4 with my TEC-140.
Blueman

I have used my ML8300 with 36mm astrodon filters on my E160 and do not get the halos or reflections. Did not even think about any other brand after my previous experience.

I have also used an SXV-H9 with old astronomik 2" filters and got bad halos.

I think the faster the system the more prone the halos??

Dean



#38 starhopper-de

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Posted 06 October 2012 - 04:44 PM

Hello Blueman,

Filters and halos, what is the answer?


I think, it depends. Baader and Astronomik deliver high quality products to the astronomical community, but it is obviously difficult to make ccd-filters for a great range of focal lenghts and telescope-filter-camera cases. I have read your posting years to late, so I will to tell you my story.
In 2008 I bought a used STL Camera with Astronomik 2C LRGBHa Filters. Everything was all right until I built a new 12" astrograph in 2009, I got reflections (now I call it halos). Example. But I haven't yet heard of that problem so I thought it was my Astrograph. One year later I switched to unmouted Baader Filters to get less vignetting. My first light was a surprise, no reflections any more. Example. Another year later I heard of the halo problem of some filters. Astronomik stated, that the halos now are gone. So in March 2011 I bought a new CCD-Camera with 31mm Astronomik narrowband Fflters, other brands do not supply unmouted 31mm for Moravian Cameras. I did my first shoots and was very surprised to see halos again. Astronomik replaced 2 of 3 filters without charge and the halos are greatly reduced.
Thanks for your posting.


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