I have made this post on CN but I also think it is worthwhile posting it here on Astrobin as it addresses a differene audience, and it might be useful for some here.
I have recently moved to a full frame imaging setup to combine with the AG Optical Convergent f/5 scope. The 6200mm pro second hand package came with a set of Chroma LRGB filters and 8nm Ha, 5nm Sii/Oiii 50mm unmounted round filters. I image from suburban Bortle 6/7 skies according to light pollution maps. I never attempted measuring my sky quality with a SQM. I decided it might be worth while to upgrade to a 3nm set of SHO filters to combat light pollution and the moon. The Chroma 3nm SHO filters are a nearly 2.5 times more expensive than the equivalent Antlia 3nm SHO set. I have seen numerous favorable reviews for the Antlia filters, and as such I thought I'd take a plunge and get the Antlia, with the ultimate plan to sell the Chroma filters instead. I recieved the filters and decided to do a head to head comparison just to make sure they are actually an "upgrade". I had a clear night last week. I decided to go for the Rosette, since it is the most reliable target in the sky with a strong signal in all three emission lines.
Here is how I designed this comparison:
All 6 filters were installed on the ZWO 7 position EFW. I made sure the orientation for both filters is the recommended orientation.
The imaging setup is:
AG Optical FA12 Convergent (12.5", f/5, FL of 1570mm). 6200mm pro cooled to -5cHAE69ecOAG-L / 174mm miniASIair.
The plan:
1) I set to image the Rosette core for a total of 6 hours, each light frame was 300s. I cycled through each filter after 6 frames and refocused with the EAF between each filter change. The idea here is to try to average out the sky conditions through the night. The moon was just over 30% illuminated and came out about 1:40am. Each filter had a final 1 hour of integration over the night. So the imaging through the night was: Chroma O > Antlia O > Chroma H> Antlia H> Chroma S> Antlia S> Antlia H> Chroma H> Antlia O> Chroma O > Antlia S>Chroma S
Total integration time for each filter was 60 minutes.
2) I took separate flat frames for each filter at the end of the imaging session, and I stacked / calibrated the frames in WBPP with 50 bias frames, Darks and Flats, under the same settings in one batch. Images were drizzled x1. Drop Shrink factor was 1.0.
3) I then processed each stack as follows: Graxpert AI (Smoothing factor was 1.0) > BlurXterminator (Correct only mode) to fix any minor guiding differences / tilt / collimation issues on equal footing. > StarXterminator > STF Autostretch histogram transformation. I elected to use starless images to just be able to judge the emission nebula details which is what we are concerned with in this comparison. Most folk replace their narrowband stars with RGB stars anyway.
Here are the limitations of this comparison:
1) I am imaging from a Bortle 6/7. The results maybe different from a more light polluted sky.
2) I only chose one target. The results maybe different on other targets.
3) The moon was only about 30% illuminated after 1:40am. Maybe on a brighter moon night the 3nm filters would be more effective? That again I am not sure of.
4) These images are JPEGs. So there maybe more details missing than the XISF file. I also have downsampled these images. I will be happy to post the full resolution of these images if requested. I think the differences could be more noticeable.
Here are the results:
Antlia Ha 3nm:
Chroma Ha 8nm: 
Antlia 3nm Sii:
Chroma 5nm Sii 
Antlia 3nm Oiii: 
Chroma 5nm Oiii:
Here are some Gifs overlying the frames with labels:
Ha:
Sii 
Oiii 
Here is also a quick comparison regarding halos tested on the star Alkaid. Frankly it looked the worst on the Chroma Oiii 5nm filter. I did not see a hint of it in my Rosette image on most other stars. I don't think this matters much imo.
There weren't any discernable halos in either the Antlia or the Chroma images that I can see in the Rosette, certainly no residuals after StarX either. Here are the the Rosette images with the stars:Chroma Oiii: 
Antlia Oiii: 
Please feel free to make any suggestions. Happy to compare the data in any other way you like.
I have recently moved to a full frame imaging setup to combine with the AG Optical Convergent f/5 scope. The 6200mm pro second hand package came with a set of Chroma LRGB filters and 8nm Ha, 5nm Sii/Oiii 50mm unmounted round filters. I image from suburban Bortle 6/7 skies according to light pollution maps. I never attempted measuring my sky quality with a SQM. I decided it might be worth while to upgrade to a 3nm set of SHO filters to combat light pollution and the moon. The Chroma 3nm SHO filters are a nearly 2.5 times more expensive than the equivalent Antlia 3nm SHO set. I have seen numerous favorable reviews for the Antlia filters, and as such I thought I'd take a plunge and get the Antlia, with the ultimate plan to sell the Chroma filters instead. I recieved the filters and decided to do a head to head comparison just to make sure they are actually an "upgrade". I had a clear night last week. I decided to go for the Rosette, since it is the most reliable target in the sky with a strong signal in all three emission lines.
Here is how I designed this comparison:
All 6 filters were installed on the ZWO 7 position EFW. I made sure the orientation for both filters is the recommended orientation.
The imaging setup is:
AG Optical FA12 Convergent (12.5", f/5, FL of 1570mm). 6200mm pro cooled to -5cHAE69ecOAG-L / 174mm miniASIair.
The plan:
1) I set to image the Rosette core for a total of 6 hours, each light frame was 300s. I cycled through each filter after 6 frames and refocused with the EAF between each filter change. The idea here is to try to average out the sky conditions through the night. The moon was just over 30% illuminated and came out about 1:40am. Each filter had a final 1 hour of integration over the night. So the imaging through the night was: Chroma O > Antlia O > Chroma H> Antlia H> Chroma S> Antlia S> Antlia H> Chroma H> Antlia O> Chroma O > Antlia S>Chroma S
Total integration time for each filter was 60 minutes.
2) I took separate flat frames for each filter at the end of the imaging session, and I stacked / calibrated the frames in WBPP with 50 bias frames, Darks and Flats, under the same settings in one batch. Images were drizzled x1. Drop Shrink factor was 1.0.
3) I then processed each stack as follows: Graxpert AI (Smoothing factor was 1.0) > BlurXterminator (Correct only mode) to fix any minor guiding differences / tilt / collimation issues on equal footing. > StarXterminator > STF Autostretch histogram transformation. I elected to use starless images to just be able to judge the emission nebula details which is what we are concerned with in this comparison. Most folk replace their narrowband stars with RGB stars anyway.
Here are the limitations of this comparison:
1) I am imaging from a Bortle 6/7. The results maybe different from a more light polluted sky.
2) I only chose one target. The results maybe different on other targets.
3) The moon was only about 30% illuminated after 1:40am. Maybe on a brighter moon night the 3nm filters would be more effective? That again I am not sure of.
4) These images are JPEGs. So there maybe more details missing than the XISF file. I also have downsampled these images. I will be happy to post the full resolution of these images if requested. I think the differences could be more noticeable.
Here are the results:
Antlia Ha 3nm:
Chroma Ha 8nm: Antlia 3nm Sii: Chroma 5nm Sii Antlia 3nm Oiii: Chroma 5nm Oiii: Here are some Gifs overlying the frames with labels:
Ha:
Sii Oiii Here is also a quick comparison regarding halos tested on the star Alkaid. Frankly it looked the worst on the Chroma Oiii 5nm filter. I did not see a hint of it in my Rosette image on most other stars. I don't think this matters much imo.
There weren't any discernable halos in either the Antlia or the Chroma images that I can see in the Rosette, certainly no residuals after StarX either. Here are the the Rosette images with the stars:Chroma Oiii: Antlia Oiii: Please feel free to make any suggestions. Happy to compare the data in any other way you like.
