I previously posted several thread on the issues that I had with reflections and artifacts with my 36mm ZWO filters. The main issue was light leakage and internal reflections that lead to very poor flat frames and artifacts in stacked images that would not easily be removed with various gradient removal tools such as pixinsight DBE. I also posted on the more generic issue of internal reflections in my OTA and how that was also effecting the quality of my images. Here are a bunch of the background threads if you want more of the history:
On reducing reflections in your imaging train:
To get to the point where I could get reasonable images, I had to debug a lot of issues. The main issue was that the ZWO filters were not fully coated to the edge. For the 1.25" filters that came in filter cells, much of this gap was covered by the cell itself. Also most buyers of the ZWO cameras and filter were getting the 1.25" filters since for the most part they were large enough so that vignetting was not an issue and they were less costly. I had the 36mm unmounted filters and along with the 31mm unmounted filters, the uncoated edge of the filters lead to a lot of leakage past the filter that caused lots of reflections and artifacts. Here are posts with a lot of data on this issue:
Once Sam at ZWO was made aware of how serious an issue this was, ZWO provided a set of rings to mask the filter edges.Sam was very responsive and I received my set of rings within about 10 days of contacting ZWO. I was not the only one who reported on this:
With the rings in place, I used my set of ZWO LRGB and NB filters for a while since it was a big chuck on change to upgrade to Astrodons. Here are some example of images with the first generation ZWO filters:
I raised a sore subject on Cloudy nights by asking is Astrodon filters were really worth 2-3X the price. I was quite sceptical at first:
However, a little while after I received my filter rings I had already pulled the trigger on a set of 36mm LRGB and NB astrodon filters. It was shortly after I purchased my Astrodons that the company was sold to farpoint. There was some chatter about quality issues with dirty or poorly packaged filters in this transfer period - apparently from vendors and not from Astrodon itself, but I believe that now these issues are resolved. However, since I had both complete sets filters on hand, I conducted my own direct comparison between my Astrodon filters and my ZWO filters to document what I saw as the advantage of Astrodon filters over the ZWO filters to help others judge for themselves whether to invest in Astrodons or not. I am a scientist and I like to both do the experimentation myself and see the data. This was my comparison thread:
In a nutshell, from my review I felt that the ZWO LRGB filters, with a mask to block the filter edge are usable and will do a decent job with few artifacts. There are some halos around bright stars, but not excessive. For the cost difference (675$ vs. 199$ for 36mm), I feel that the ZWO LRGB filters are worth strong consideration. However, due to the halos on the ZWO narrowband filters combined with the edge leakage, I felt that the narrowband filters were not a good buy. I used my Astrodons exclusively for about the last six months and have been happy with them. I have made may best images with them.
About a month ago, there was a thread about an new generation of ZWO Narrowband filters being offered on the ZWO website. I took a look, but since I did not have a need it was just for curiosity. About 2 days later, I received an e-mail from Sam telling me about the new filters and asking if I would do a similar test with the new product. I jumped at the chance. I took me a month to collect and analyze the data. We had lots of clouds and a huge hear wave in Austin. I also had some serious issues with some of my equipment, so this took longer than I would have liked.
Regardless, this thread is my review of the new ZWO narrowband filters (36mm Ha, SII and OII) vs my astrodon filters. I tried as best I could to make this as fair and thorough an evaluation as I could. If anyone has any request for additional data, let me know and I will see if I can squeeze it in. Even though all the data is collected and analyzed, it is going to take some time to get it all posted. So please bare with me. I will cover:
1) unboxing, inspection and mounting of the filters into the filter wheel.
2) flat frame comparisons
3) stacked, drizzled mono images for the filters
4) HSO hubble palette processed image comparisons.