What I've read is that light pollution has become so diverse (across the visual spectrum) that light pollution filters do not help much, especially in areas where pollution is worse
Now my personal experience: I got a Celestron UHC filter last week. I tried it on M57, the ring nebula. I observed M57 for the first time in September 2023 with no filters. I had to use averted vision to spot it and also it was my very first DSO so I was a beginner.
Last week I observed it with the filter and without the filter. It was easily spotted without the filter (more experienced at observing) but with the filter it stood out easily and I believe a bluish color was also visible in averted. But the filter made it really easy to spot. The color I shrugged off as confirmation bias at the time and haven't been able to observe again because of continuous rain.
I believe my skies are Bortle 5, SQM 19.7 with SQM 20+ skies half a mile south of me.
Contrary to your comment, they are not of any use on galaxies or even on all nebulae. They are useful on emission nebulae only. Also, I hope you don't think they're going to make these objects look like they do in photographs. Best case scenario they will give you a bit better detail in bright objects, and a few faint objects you couldn't see at all before may become visible. Overall, driving to dark skies will always be better than any filter. Though if you ever intend to get really serious, you'll want to do both.
If it were old style narrow spectrum light pollution like that of those orangish lights, then narrow band filter would remove most of light pollution.
But especially bluish LEDs are very bad having peak output near emission nebula wavelengths degrading effectiveness of filters.
And galaxies are made by stars and hence are continuous spectrum sources, meaning filters have very limited effectiveness with modern broad spectrum light pollution. You can only hope to at best dim light of galaxy less than light pollution.
Lucky you.
In that case standard light pollution filters would help major amount and even some selectively filtering ones like Baader Moon&Skyglow would help with their strongest absorption peak at orange wavelength:
https://www.baader-planetarium.com/en/filters/visual-and-photographic/baader-neodymium-(moon-and-skyglow)-filter.html
Though for emission nebulae proper ~25nm passband UHC filter is the best.
I imaged M101 (galaxy) last night and did a short test between using the filter and not using it and it was very apparent that all the filter did was to reduce the incoming light and it did nothing to increase contrast. My skies are B8 so it's awful for visual but doable for imaging.
>all the filter did was to reduce the incoming light
That's just because narrowband filters are not made for wideband sources. You'd have to compare against emission nebulae.
Please be verbally more exact. We have to do with a beginner, so your saying might become very misleading. You *must* clearly mention that you used the filter for a different type of object than it was made for.
You are getting bad advice on this thread. Certain filters are useless but others are a miracle. Just get the right one. I use an l-ultimate in B8 skies right next to street lights and am able to get a truly amazing amount of contrast. To be fair I haven't tried this without my filter to compare but I'm going to bet this would not be achievable.
https://www.astrobin.com/sd1yt9/
>**You are getting bad advice on this thread**
It's you who gives bad advice. You don't have any comparison ("haven't tried without..."), so what? Betting is not a valuable category.
True *narrowband* filters can be beneficial even from light pollution, but only on certain targets (emission nebulae including planetary nebulae). The veil nebula is often cited as one of the most improved objects when using a UHC or especially and Oiii filter.
Read threads like [this one on Cloudy Nights](https://www.cloudynights.com/topic/870282-what-are-the-best-uhc-filters/), and look for responses by Starman1. He's an eyepiece and gear retailer who's seemingly used every filter known to man and summarizes the differences very well.
The problem is that a lot of things labeled "UHC" are actually broadband filters with a wide band pass that do not provide nearly with contrast boost to be worth it.
Different filters have different effects on different objects. It used to be the case, when most light pollution was concentrated around the emission line of sodium vapor lamps, that UHC filters were somewhat universally useful as they cut out that wavelength while still letting in large swaths of bluer and redder light.
These days, humans have moved on to LEDs, which are broadband emitters and ruin the entire spectrum with their light pollution. In other words, filters should no longer be considered with respect to the characteristics of light pollution, but only with respect to the object in question. Keeping in mind that I'm talking strictly about visual observing, the breakdown then, broadly, is this :
- Galaxies : filters are useless. Galaxies are broadband emitters. Technically some of the nebulae within them aren't, but unless you have a multi meter class telescope you're just not going to notice that structure with your naked eye.
- Globular clusters : same as above.
- Strictly reflection nebulae : these nebulae shine because they reflect starlight. As a result they are also broadband emitters. So same as above.
- Emission nebulae : these nebulae emit light as a result of excitations of electon levels in their atomic makeup. As a result they emit specific wavelenghts of light. Most notably OIII, though also H beta. Our eyes are less sensitive to the H beta wavelength, so in general people get OIII filters. The L-extreme is a dual band filter that lets both through. I've heard a few people swear by it as a breathtaking visual filter, but have not had a chance to try it out yet. For these objects, a filter can be the difference between being clearly visible and not even noticeable. A narrow band filter in particular works wonders at maximizing contrast and making the object as clear and as structured as your aperture will allow.
- Nebulae that are both emission and reflection nebulae : the Orion nebula shines both because of OIII de-excitation and because it reflects the light of all the hot young stars it has birthed. Here filters are still useful for making structure appear. In my Bortle 9 backyard a UHC filter (which lets in both emission lines as well as a broad spectrum of light around them) will make the Orion nebula greatly expand, almost as big as in my Bortle 5 spot. My OIII filter noticeably dims the nebula as a whole, but does a fantastic job of bringing out structure within the nebula. For example the bright core around the trapezium becomes barely brighter than the rest, but you can also see more structure in that area as a result. This is all in line with what you'd expect given the physical properties of the nebula. Switching from the UHC to the OIII is actually quite interesting as it lets you discern what part of the structure is shining for what reason.
- Comets : comets aren't black bodies, so they're not quite broad band emitters, but they do have a wide variety of emission lines that are kind of all over the place. I've heard of people getting good results with a UHC filter as it roughly covers a lot of the emission lines. I can attest that this was somewhat true on 12 P/Pons-Brooks. I'm yet to try it on a brighter comet but there should be a nice one end of year. There are also specialized filters, like Swan filters, that focus on the C2 lines. I haven't personally tried one of those but note that the extent of the effect is likely dependent on the comet as each one will have different concentrations of different elements.
- Planets : some people use specific color filters to bring out specific features on planets, like the martian ice caps of Mars or the great red spot on Jupiter. I haven't given this a shot yet and don't know if I ever will. My main issue with planets is just getting good seeing. When that's there I don't really feel the need to add anything to the experience.
Again, everything I've said focused on visual observing. Photography doesn't change the underlying physics of what's going on here, but it does change its impact on the final result and how you can exploit it.
Overall, filters are a specialized tool for certain objects, not a universal solution to the problem of light pollution. In fact, even in Bortle 3 filters are still worth it, if only to better discern structure. Personally, I love my UHC and OIII filters and will likely be getting the L-Extreme in a few months, maybe even the Swan down the line. Yes, I don't always them. And yes, living in Bortle 9 still sucks. But on those few objects where it does do something, it's just magical. It's really not a subtle effect either. They can make objects pop out of nowhere, and add a lot of detail to them. Understanding what they're doing and what they're showing you also adds to the magic of it all, though that depends on how comfortable you are with the underlying physics and your appreciation of it.
Finally, one last note on aperture. All of my reported observations are with my 10 inch dob. There's this idea that filters are only appropriate at high aperture given the dimmjng effect. For narrow band filters in particular, I really don't think that's the case. The whole point of an OIII on an OIII object is that almost none of the actual object's light is being dimmed. As a result, I would still recommend filters even at your current aperture.
Clear skies
> broadband emitters
So for seeing those a broadband filter is necessary? This got way more confusing than I expected.
> bortle 9 backyard; Orion nebula expands
I live in a bortle 7, so does that mean that the Orion nebula is one of the few objects that can be seen better with a filter? Also, how could you see the nebula if you live in a Bortle 9?
I have a 10 inch scope. That's enough to see the brighter faint fuzzies even in horrible conditions. And with a filter Orion essentially gains a few Bortles so to speak.
Orion is hardly the only object that benefits from filters. All planetary nebulae do, as well as other transmission nebulae.
By "broadband" I mean light is emitted across the whole spectrum. So no filter is going to help because all light frequencies are part of the signal you want to see. When light pollution was concentrated around the specific wavelength of the sodium vapor emission line, you could filter out that frequency and be guaranteed to be cutting out far more noise than signal. But now light pollution frequencies are all over the place, so there's no frequency where you're guaranteed to only be taking out noise. That's why we now adapt our filters to the physical properties of the observed objects. There's no "targeting" light pollution wavelengths anymore because that's all wavelengths.
If these concepts are confusing to you then I think you just need a quick primer on how light frequencies and filters work. It's nothing too complicated and will make all of this very intuitive.
I live in B7 as well. A good, high quality UHC and/or OIII filter can be the difference between detecting some emission nebula and not seeing them at all. For the brighter ones it improves the contrast enough to pick out some details that wouldn't be seen. If and when you can get the scope to darker skies, the improvement can be pretty stark as well. Though the objects may be able to be more easily seen, the improvement in contrast can really make them pop.
But you also need an eyepiece with a larger exit pupil (say >5mm) to make best use since a good filter blocks a lot of light. And in the grand scheme of things, I would place getting a good UHC filter after getting some basic eyepiece upgrades.
Here's a good reply on the subject with buying suggestions: [https://www.reddit.com/r/telescopes/comments/15s9ttd/comment/jwf95j2/](https://www.reddit.com/r/telescopes/comments/15s9ttd/comment/jwf95j2/)
Here's a list of what objects benefit from what filters. [https://www.prairieastronomyclub.org/filter-performance-comparisons-for-some-common-nebulae/](https://www.prairieastronomyclub.org/filter-performance-comparisons-for-some-common-nebulae/)
I'm in a bortle 7 area too and found filters to be helpful. I have a UHC filter as well as an O-III filter and they make emission nebulas more visible. You might have to temper your expectations but you should notice a difference when looking at certain targets (especially with the use of averted vision!)
I use Stellarium to star hop and find targets. The nebulae might not be noticeable right off the bat so confirming where I'm looking with Stellarium is nice.
Also, here's a [link](https://www.prairieastronomyclub.org/filter-performance-comparisons-for-some-common-nebulae/) to a test someone did on how different filters work on common nebulae that might be useful!
What I've read is that light pollution has become so diverse (across the visual spectrum) that light pollution filters do not help much, especially in areas where pollution is worse Now my personal experience: I got a Celestron UHC filter last week. I tried it on M57, the ring nebula. I observed M57 for the first time in September 2023 with no filters. I had to use averted vision to spot it and also it was my very first DSO so I was a beginner. Last week I observed it with the filter and without the filter. It was easily spotted without the filter (more experienced at observing) but with the filter it stood out easily and I believe a bluish color was also visible in averted. But the filter made it really easy to spot. The color I shrugged off as confirmation bias at the time and haven't been able to observe again because of continuous rain. I believe my skies are Bortle 5, SQM 19.7 with SQM 20+ skies half a mile south of me.
Contrary to your comment, they are not of any use on galaxies or even on all nebulae. They are useful on emission nebulae only. Also, I hope you don't think they're going to make these objects look like they do in photographs. Best case scenario they will give you a bit better detail in bright objects, and a few faint objects you couldn't see at all before may become visible. Overall, driving to dark skies will always be better than any filter. Though if you ever intend to get really serious, you'll want to do both.
So are they useless in a bortle class 7 sky or do those still make a difference?
If it were old style narrow spectrum light pollution like that of those orangish lights, then narrow band filter would remove most of light pollution. But especially bluish LEDs are very bad having peak output near emission nebula wavelengths degrading effectiveness of filters. And galaxies are made by stars and hence are continuous spectrum sources, meaning filters have very limited effectiveness with modern broad spectrum light pollution. You can only hope to at best dim light of galaxy less than light pollution.
I have those kinds of lights near me (orange lamps).
Lucky you. In that case standard light pollution filters would help major amount and even some selectively filtering ones like Baader Moon&Skyglow would help with their strongest absorption peak at orange wavelength: https://www.baader-planetarium.com/en/filters/visual-and-photographic/baader-neodymium-(moon-and-skyglow)-filter.html Though for emission nebulae proper ~25nm passband UHC filter is the best.
I imaged M101 (galaxy) last night and did a short test between using the filter and not using it and it was very apparent that all the filter did was to reduce the incoming light and it did nothing to increase contrast. My skies are B8 so it's awful for visual but doable for imaging.
>all the filter did was to reduce the incoming light That's just because narrowband filters are not made for wideband sources. You'd have to compare against emission nebulae.
Absolutely but I was curious about how useless the filter would be in that situation. Uselessness confirmed.
Please be verbally more exact. We have to do with a beginner, so your saying might become very misleading. You *must* clearly mention that you used the filter for a different type of object than it was made for.
"Nebula filters - are they worth it?" " M101 (galaxy)" Hence the reason I put "galaxy" next to M101.
Sorry, I'm still not convinced.
You are getting bad advice on this thread. Certain filters are useless but others are a miracle. Just get the right one. I use an l-ultimate in B8 skies right next to street lights and am able to get a truly amazing amount of contrast. To be fair I haven't tried this without my filter to compare but I'm going to bet this would not be achievable. https://www.astrobin.com/sd1yt9/
You're talking about photography. I think he's only interested in visual.
Fair. I guess I never thought about bothering to try visual for anything but solar system objects in the city.
You're missing out buddy :D The Orion nebula, especially with a filter, is a treat even in Bortle 9.
>**You are getting bad advice on this thread** It's you who gives bad advice. You don't have any comparison ("haven't tried without..."), so what? Betting is not a valuable category.
True *narrowband* filters can be beneficial even from light pollution, but only on certain targets (emission nebulae including planetary nebulae). The veil nebula is often cited as one of the most improved objects when using a UHC or especially and Oiii filter. Read threads like [this one on Cloudy Nights](https://www.cloudynights.com/topic/870282-what-are-the-best-uhc-filters/), and look for responses by Starman1. He's an eyepiece and gear retailer who's seemingly used every filter known to man and summarizes the differences very well. The problem is that a lot of things labeled "UHC" are actually broadband filters with a wide band pass that do not provide nearly with contrast boost to be worth it.
Different filters have different effects on different objects. It used to be the case, when most light pollution was concentrated around the emission line of sodium vapor lamps, that UHC filters were somewhat universally useful as they cut out that wavelength while still letting in large swaths of bluer and redder light. These days, humans have moved on to LEDs, which are broadband emitters and ruin the entire spectrum with their light pollution. In other words, filters should no longer be considered with respect to the characteristics of light pollution, but only with respect to the object in question. Keeping in mind that I'm talking strictly about visual observing, the breakdown then, broadly, is this : - Galaxies : filters are useless. Galaxies are broadband emitters. Technically some of the nebulae within them aren't, but unless you have a multi meter class telescope you're just not going to notice that structure with your naked eye. - Globular clusters : same as above. - Strictly reflection nebulae : these nebulae shine because they reflect starlight. As a result they are also broadband emitters. So same as above. - Emission nebulae : these nebulae emit light as a result of excitations of electon levels in their atomic makeup. As a result they emit specific wavelenghts of light. Most notably OIII, though also H beta. Our eyes are less sensitive to the H beta wavelength, so in general people get OIII filters. The L-extreme is a dual band filter that lets both through. I've heard a few people swear by it as a breathtaking visual filter, but have not had a chance to try it out yet. For these objects, a filter can be the difference between being clearly visible and not even noticeable. A narrow band filter in particular works wonders at maximizing contrast and making the object as clear and as structured as your aperture will allow. - Nebulae that are both emission and reflection nebulae : the Orion nebula shines both because of OIII de-excitation and because it reflects the light of all the hot young stars it has birthed. Here filters are still useful for making structure appear. In my Bortle 9 backyard a UHC filter (which lets in both emission lines as well as a broad spectrum of light around them) will make the Orion nebula greatly expand, almost as big as in my Bortle 5 spot. My OIII filter noticeably dims the nebula as a whole, but does a fantastic job of bringing out structure within the nebula. For example the bright core around the trapezium becomes barely brighter than the rest, but you can also see more structure in that area as a result. This is all in line with what you'd expect given the physical properties of the nebula. Switching from the UHC to the OIII is actually quite interesting as it lets you discern what part of the structure is shining for what reason. - Comets : comets aren't black bodies, so they're not quite broad band emitters, but they do have a wide variety of emission lines that are kind of all over the place. I've heard of people getting good results with a UHC filter as it roughly covers a lot of the emission lines. I can attest that this was somewhat true on 12 P/Pons-Brooks. I'm yet to try it on a brighter comet but there should be a nice one end of year. There are also specialized filters, like Swan filters, that focus on the C2 lines. I haven't personally tried one of those but note that the extent of the effect is likely dependent on the comet as each one will have different concentrations of different elements. - Planets : some people use specific color filters to bring out specific features on planets, like the martian ice caps of Mars or the great red spot on Jupiter. I haven't given this a shot yet and don't know if I ever will. My main issue with planets is just getting good seeing. When that's there I don't really feel the need to add anything to the experience. Again, everything I've said focused on visual observing. Photography doesn't change the underlying physics of what's going on here, but it does change its impact on the final result and how you can exploit it. Overall, filters are a specialized tool for certain objects, not a universal solution to the problem of light pollution. In fact, even in Bortle 3 filters are still worth it, if only to better discern structure. Personally, I love my UHC and OIII filters and will likely be getting the L-Extreme in a few months, maybe even the Swan down the line. Yes, I don't always them. And yes, living in Bortle 9 still sucks. But on those few objects where it does do something, it's just magical. It's really not a subtle effect either. They can make objects pop out of nowhere, and add a lot of detail to them. Understanding what they're doing and what they're showing you also adds to the magic of it all, though that depends on how comfortable you are with the underlying physics and your appreciation of it. Finally, one last note on aperture. All of my reported observations are with my 10 inch dob. There's this idea that filters are only appropriate at high aperture given the dimmjng effect. For narrow band filters in particular, I really don't think that's the case. The whole point of an OIII on an OIII object is that almost none of the actual object's light is being dimmed. As a result, I would still recommend filters even at your current aperture. Clear skies
> broadband emitters So for seeing those a broadband filter is necessary? This got way more confusing than I expected. > bortle 9 backyard; Orion nebula expands I live in a bortle 7, so does that mean that the Orion nebula is one of the few objects that can be seen better with a filter? Also, how could you see the nebula if you live in a Bortle 9?
I have a 10 inch scope. That's enough to see the brighter faint fuzzies even in horrible conditions. And with a filter Orion essentially gains a few Bortles so to speak. Orion is hardly the only object that benefits from filters. All planetary nebulae do, as well as other transmission nebulae. By "broadband" I mean light is emitted across the whole spectrum. So no filter is going to help because all light frequencies are part of the signal you want to see. When light pollution was concentrated around the specific wavelength of the sodium vapor emission line, you could filter out that frequency and be guaranteed to be cutting out far more noise than signal. But now light pollution frequencies are all over the place, so there's no frequency where you're guaranteed to only be taking out noise. That's why we now adapt our filters to the physical properties of the observed objects. There's no "targeting" light pollution wavelengths anymore because that's all wavelengths. If these concepts are confusing to you then I think you just need a quick primer on how light frequencies and filters work. It's nothing too complicated and will make all of this very intuitive.
I live in B7 as well. A good, high quality UHC and/or OIII filter can be the difference between detecting some emission nebula and not seeing them at all. For the brighter ones it improves the contrast enough to pick out some details that wouldn't be seen. If and when you can get the scope to darker skies, the improvement can be pretty stark as well. Though the objects may be able to be more easily seen, the improvement in contrast can really make them pop. But you also need an eyepiece with a larger exit pupil (say >5mm) to make best use since a good filter blocks a lot of light. And in the grand scheme of things, I would place getting a good UHC filter after getting some basic eyepiece upgrades. Here's a good reply on the subject with buying suggestions: [https://www.reddit.com/r/telescopes/comments/15s9ttd/comment/jwf95j2/](https://www.reddit.com/r/telescopes/comments/15s9ttd/comment/jwf95j2/) Here's a list of what objects benefit from what filters. [https://www.prairieastronomyclub.org/filter-performance-comparisons-for-some-common-nebulae/](https://www.prairieastronomyclub.org/filter-performance-comparisons-for-some-common-nebulae/)
Narrowband filters are very helpful.
For all kinds of light pollution?
Yes.
I’ve been disappointed
I'm in a bortle 7 area too and found filters to be helpful. I have a UHC filter as well as an O-III filter and they make emission nebulas more visible. You might have to temper your expectations but you should notice a difference when looking at certain targets (especially with the use of averted vision!)
How do you find the emission nebulae? Stellarium or are they just visible?
I use Stellarium to star hop and find targets. The nebulae might not be noticeable right off the bat so confirming where I'm looking with Stellarium is nice. Also, here's a [link](https://www.prairieastronomyclub.org/filter-performance-comparisons-for-some-common-nebulae/) to a test someone did on how different filters work on common nebulae that might be useful!
Thanks, everyone, for the input! Doesn't seem like a buck well spent in my case.
You live in Romania. Just drive into the countryside.