Upgrading narrowband filters: is it worth switching from 7 mm to 3nm? - Forums

Topic starter

12 hours ago

Hello all.

With galaxy season coming to a close, I've started a narrowband project for my monochrome camera. With only preliminary data, I noticed a severe problem with my ZWO OIII 7 mm filter. It seems to produce terrible halos around bright stars (I’ve included the images below) and this is apparently a very common problem with this filter. I've upgraded to the Antlia OIII 3 nm filter and I'm waiting for it to arrive.

I wanted to ask experienced people in the community, do you think it's worth it to upgrade my other Ha and SII 7 nm narrowband filters while I'm at it? Those filters don't seem to produce artifacts but I'm mainly asking with regards to the benefit of going to a smaller bandpass.

Thanks very much for your input!

📷 1000012068.jpgfirst image description: HOO image of zeta oph. Very noticable halo around the bright central star.

📷 1000012062.jpgsecond image description: same as first image but only Ha data. No noticeable artifacts.

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Rick Krejci

4 hours ago

How much light pollution are you dealing with? If you’re not at a dark site, then generally the narrower the better. And, even at a dark site, narrower will allow better imaging with the moon out.

I have the Antlia Edge 4.5nm filters as well as Chroma 3nm. They are both solid with no halos. I used to use the Zwo 7nm and, yes, they have halos on Oiii, but they were inexpensive. To me, the Antlias are the best bang for the buck, with high transmission and no halos. Chromas are simply the best, but cost as such.

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Dave Stirling

2 hours ago

Nikhil · May 28, 2026 at 05:02 AM
Hello all.
With galaxy season coming to a close, I've started a narrowband project for my monochrome camera. With only preliminary data, I noticed a severe problem with my ZWO OIII 7 mm filter. It seems to produce terrible halos around bright stars (I’ve included the images below) and this is apparently a very common problem with this filter. I've upgraded to the Antlia OIII 3 nm filter and I'm waiting for it to arrive.
I wanted to ask experienced people in the community, do you think it's worth it to upgrade my other Ha and SII 7 nm narrowband filters while I'm at it? Those filters don't seem to produce artifacts but I'm mainly asking with regards to the benefit of going to a smaller bandpass.
Thanks very much for your input!
📷 1000012068.jpgfirst image description: HOO image of zeta oph. Very noticable halo around the bright central star.
📷 1000012062.jpgsecond image description: same as first image but only Ha data. No noticeable artifacts.

I think halos are a function of the quality of the filter rather than the bandpass. You would likely see improvement in halos around OIII specifically with the higher quality filter, so it would be interesting to see how much halos diminish by swapping out the OIII with the new filter you’ve ordered first. Highly recommend 3nm for high light pollution (I’m in Bortle 6).

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