So I bought the Antlia 3nm Ha filter a few months ago. I have used it extensively and like it a lot. The O3 and S2 filters then came in and I did a comparison of all three filters versus my Baader filters.
The Baader filters have various bandpasses of 7nm for Ha, 8.5nm for O3 and 8nm for S2. The Antlia's are all 3nm. The Antlia's are the most recent filters. In my case all these filters are 2" mounted and this comparison was done with a Tak FSQ 106 and an ASI 6200mm camera.
There has been a lot of discussion on CNs about these Antlia filters and whether they are a poor man's version of Chroma or Astrodon filters.
My general observations are as as follows:
1. The Antlia Ha filter produces next to no halos and is a nice alternative to the Baader Ha filter.
2. The O3 filter is better than the Baader O3 filter. There are still halos. They are not as pronounced, but they are there. O3 filters are tough in this regard.
3. The Antlia S2 filter is again slightly better than the Baader filter w.r.t. halos. Seems to work fine.
4. 3nm filters gather less light. That might be great in light polluted skies. I was able to stretch the 3nm data and get good images. But the wider bandpasses allowed more light to pass.
5. Personally, I think processing is more important thant filter issues such as halos. Either set gives good images.
6. For the price difference I would buy the Antlia filters. IMHO I don't think filters 2-3x more expensive are worth the cost.
7. 2" mounted filters work with full frame cameras. There is vignetting. There are reflections off the metal mounting rings. My Baader 7nm Ha filter had pronounced reflections. It showed up in flats and made it hard to calibrate out. I took the filter apart and painted the metal rings flat black which helped with reflections and made the flats work much better. This is a drag. I think it is an issue with all 2" mounted filters. 2" mounted filters are more than enough for APS sized sensors without having to worry about this issue.
The next posts will show some comparisons. These are stacks of 27x5m images with simple level stretches to bring out the halos. If you looked at one sub you would see the same. The stacks were done in APP with dark, bias and flat frames. I am showing crops on the few bright stars in the image. I think this is representative of most imaging. There have been some Antlia images posted on very bright stars including Sirius. Personally,I wouldn't make a decision based upon performance on the brightest stars in the sky.