Terrible halos with ZWO filters - what´s wrong?

martinf

Tonight I tried an imaging run on the area around Sadr and noticed that my ZWO filters give me really nasty reflections from bright stars (see attached)!! My Astrodon Ha-filter is miles better!

My ZWO filters are unmounted 31mm filters and I use the EFW-8 with my ASI1600MM-Cool.

The attached images are stacks of 180 second OIII subs and 300s SII subs. As you can see, the halo covers a large part of the frame and is layered into different sizes.

Is this to be expected from the ZWO filters or am I doing something wrong? If the filters are not better than this I cannot use them. Or is it because of the camera?

O3.JPG

S2.JPG

martinf

Here is a comparison using my Astrodon 3nm Ha-filter (1.25" mounted). Sure, there is a halo but not at all that bad.

Ha.JPG

Support@ZWO

It's a unfare comparison. Ha VS OIII.

Ha should compare with Ha filter.

OIII filter because it is between Blue and Green light, glass base is different, so the reflection is worse than our Ha and SII filters.

Another thing is check the positive and nagitive sides of filter, maybe wrong side will make halo worse.

martinf

Sean.Wang wrote:
It's a unfare comparison. Ha VS OIII.

Ha should compare with Ha filter.

OIII filter because it is between Blue and Green light, glass base is different, so the reflection is worse than our Ha and SII filters.

Another thing is check the positive and nagitive sides of filter, maybe wrong side will make halo worse.

OK, maybe OIII is more sensitive but SII is also in the red spectrum and the halo is almost as big on that one (the biggest outer halo a bit dimmer).

What is the positive and negative side?

martinf

Sean.Wang wrote:
It's a unfare comparison. Ha VS OIII.

Ha should compare with Ha filter.

OIII filter because it is between Blue and Green light, glass base is different, so the reflection is worse than our Ha and SII filters.

Another thing is check the positive and nagitive sides of filter, maybe wrong side will make halo worse.

I checked my filters now and the S2 might have been reversed so I changed that, but the OIII is the correct side while giving these reflections.

I read somewhere that you were aware of the problems with these 31mm unmounted filters and provide a filter mask/ring? My ZWO filters are from july 2017, so that would be the old version?

martinf

Reading this thread, it is obvious that the ZWO filters I bought with my camera are not good. The test image for the O3 filter shows exactly the same kind of huge halos that I got:

https://www.cloudynights.com/topic/627187-review-of-the-new-zwo-narrowband-filters-comparison-to-the-old-zwo-and-astrodon-filters/

I will be buying a Baader O3-filter to see if that works better. Don´t want to spend more money on ZWO filters having already spent a lot of money (for me) on the original NB filter set...

Support@ZWO

MartinF wrote:
Reading this thread, it is obvious that the ZWO filters I bought with my camera are not good. The test image for the O3 filter shows exactly the same kind of huge halos that I got:

https://www.cloudynights.com/topic/627187-review-of-the-new-zwo-narrowband-filters-comparison-to-the-old-zwo-and-astrodon-filters/

I will be buying a Baader O3-filter to see if that works better. Don´t want to spend more money on ZWO filters having already spent a lot of money (for me) on the original NB filter set...

Hi there

I saw the pervious reply said it is bought in 2017, I think the narrowband filter must be the old ones.

We start to sell the new narrowband filter in 2018. now there won't be much halo of Ha and SII filters.

Support@ZWO

To be honest, your Astrodon narrowband filter is quite great.

martinf

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Support@ZWO

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suvowner

you have definitely improved ha and SII for 2018, but not much change in OIII ??

why not on OIII ??

Support@ZWO

suvowner wrote:
you have definitely improved ha and SII for 2018, but not much change in OIII ??

why not on OIII ??

OIII filter is different, 500nm , can't use same red glassbase as Ha and SII. We still make improvement, the quality is better than before.