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Old 15-10-2020, 10:08 PM
MarkInSpace (Mark)
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How Narrow do I need for mom filters?

I see 6,28,35nm for Oiii, Ha etc.
Do they need to be in the <10nm range to be good for monochrome filters?
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Old 16-10-2020, 05:08 PM
jahnpahwa (JP)
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I'm not highly qualified to answer, but its nearing 24hrs with no response.
My answer is yes, you want to be below 10nm, especially with Oiii. Some people go 5 or 6nm for Ha and Sii, and 3nm for Oiii. Oiii seems to be most impacted by moonglow. I use zwo 7nm across the three and definitely notice the extra noise with Oiii. I wonder about getting 3nm version for that one in particular. But yeah 5 or 6nm are the standard, it seems. I went 7nm zwo for cost reasons
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Old 16-10-2020, 05:42 PM
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Here you go...

Less bandwidth = more contrast.
5nm is best when used under light polluted conditions.
3nm O3 can be used successfully under bright moonlight.
3-5 nm cost a LOT more but are well worth it!
Top of the range are Astrodon & Chroma, but Chroma represent considerably better value than Astrodon for exactly the same quality.
Bottom of the price bracket - ZWO, Optolong etc. produce haloes around bright stars
= You get what you pay for!

Hope that's useful.
Cheers
Andy
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Old 16-10-2020, 05:44 PM
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Is that a typo "mom filters"? No such term.

But to answer your question its common to use 5nm for Ha and 3nm for O111 and S11. Ha needs to be a bit wider as it allows N11 to be captured.

Greg.
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Old 16-10-2020, 06:32 PM
Emuhead
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Any harm in going 3nm across the board? Is NII significant enough to make me want to buy a 5nm also? I've seen your photos Andy and am blown away. . If I can get that kind of detail using just 3nm then that would save some dollars, but if 5nm has to be done, well I've come this far..
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Old 16-10-2020, 06:46 PM
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Nikolas (Nik)
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Quote:
Originally Posted by Andy01 View Post
Here you go...


Bottom of the price bracket - ZWO, Optolong etc. produce haloes around bright stars
= You get what you pay for!

Hope that's useful.
Cheers
Andy

I can't speak for mono filters but I've never had haloes around my optolong filters, in particular the L-enhance and L-Pro this is for OSC filters however
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Old 16-10-2020, 09:28 PM
MarkInSpace (Mark)
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oops, yes I mean mono!!!
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Old 16-10-2020, 10:30 PM
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Andy01 (Andy)
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Quote:
Originally Posted by Emuhead View Post
Any harm in going 3nm across the board? Is NII significant enough to make me want to buy a 5nm also? I've seen your photos Andy and am blown away. . If I can get that kind of detail using just 3nm then that would save some dollars, but if 5nm has to be done, well I've come this far..
3nm are more expensive than 5nm which in turn are more expensive than 7 or 10 nm.
As Greg mentioned, 5nm ha also includes N2 signal. 3nm Ha excludes this so most serious narrowband imagers get 3nm O3 & 5nm Ha. The S2 can be either depending on your sky conditions.
Cheers
A
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Old 17-10-2020, 06:10 AM
Emuhead
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Hi Greg, not sure if it's helpful to you but the optolong L-Enhance & L-Extreme will work well with your 294MC. Lots of good reviews on those. You can even split out the RGB channels & process them separately in a mono kind of way, recombining into a narrowband image.

Last edited by Emuhead; 17-10-2020 at 07:08 AM.
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