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Filter Advice Please


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Trying to find a filter that will help me see nebulas and planetary nebulas a little more.

Getting a little confused by it all TBH.

Will a UHC Filter allow me to see more detail in nebulas like M42 and will the work just as well on objects like the Crab and Owl Nebula?

Or are they do they require two different types of filter?

What are the better makes of these filters ?

I'm sure this question has been asked 100's of times before, so sorry for repeating it.....

Thanks in Advance

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I found the following report by Dave Knisely very useful in learning what type of filter to try on which objects.  And it helped me decide which one to get first to test the waters.
https://www.prairieastronomyclub.org/filter-performance-comparisons-for-some-common-nebulae/

I would add that you really need good dark skies to observe these types of objects - and under these conditions the filters really help. 
The scores of 5 in the above list really are that good and the resulting "wow"s I've had with them have made my purchase of good quality versions of the filters worth every penny.   
If you expect a filter to compensate for not having dark skies then I think you will be disappointed.

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Some good advice already provided.

I'll just add that, of the ones that I've owned, the ones that had the most impact visually have been UHC and O-III filters (especially the latter on certain targets) branded Astronomik, DGM and Lumicon (an early one). The Tele Vue Bandmate Type 2 have also developed a very good reputation.

Some lower cost filters that I've tried have much less impact. One exception to that is the Orion Ultrablock (a UHC type) but I'm told those can be variable.

 

Edited by John
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Yes a UHC filter will help with observing all those nebulae and is a good all rounder nebula filter.

You can get more specialist filters that will do better in certain circumstances, which many obervers have, but then you are getting into choices with diminishing returns.

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As I recently said in another related thread, the fairly inexpensive Svbony UHC has performed quite well for me relative to my Lumicon UHC filter.  If your funds are limited, I recommend testing the waters with it.

 

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Thank you to everyone who has replied, your input is greatly appreciated.

@globularThanks for the link, looks like the test that guy has done seem quite comprehensive. I'll have a proper read through over the weekend and hopefully get a better understanding too.

 

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I have one of the old Lumicon O-IIIs. It's excellent but I wouldn't recommend it with small scopes as it is quite strong. It suits my 12" quite well though I need to confess to being in a high LP area.

That one is only 1.25". I have a 2" 'basic' from FLO which seems decent enough for the low price.

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10 hours ago, Ed in UK said:

Thank you to everyone who has replied, your input is greatly appreciated.

@globularThanks for the link, looks like the test that guy has done seem quite comprehensive. I'll have a proper read through over the weekend and hopefully get a better understanding too.

 

Ed,

A good narrowband filter passes the H-ß spectral line at 486.1nm and the two O-III lines at 495.9nm and 500.7nm.

Since those lines in the spectrum seem to be emitted by most nebulae, the narrowband filter is the "universal emission nebula" filter.

You don't have to know the spectrum of the object to figure out which filter to use.

It will enhance just about any nebula that emits light.  It likely won't help on reflection or dark nebulae.

The important specs are: 22-28nm bandwidth, and >90% transmission at all 3 lines in the spectrum.

The filters that do this are:

Astronomik UHC Visual

Tele Vue BandMate II Nebustar

Orion Ultrablock

Lumicon UHC

DGM NPB

Many "UHC" filters have wider bandwidths and enhance the nebula much more weakly.  They go by names like:

UHC-S, UHC-E, UHC/LPR, UHC-L

I suggest staying away from them.

So far, I have not seen a filter from China that met the standards of a good narrowband filter, though a few have come close.

If you stick to the ones above, you'll do fine.

As for size, since the filter will be used below a magnification of 12x/inch of aperture, match your lowest power eyepiece for size.  You won't be using it at higher powers due the darkening

of nebulae with increased magnification.

 

Where line filters like a dedicated H-ß filter or O-III filter come into play is where the nebula emits primarily energy in one or the other, but not both.

A line filter can yield a bit higher contrast.  If you find observing nebulae is what you want to do, then add a good O-III filter to the mix, but you can wait on that.

Spend a little more money on the Narrowband filter first, because it will get the most use.

This summary of what nebula filters are and how they work, and the types might be educational:

https://www.cloudynights.com/topic/901098-light-pollution-filter-reviews/?p=13092087

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Of all the UHC filters I have used my Tele Vue BandMate II Nebustar  is by far the best. Baader also makes excellent filters and have had great success with their Oiii filters, although since I only use a small refractor I now only use the Tele Vue BandMate II Nebustar filter, in fact it is the only filter I use these days. I would personally avoid cheap filters, you get what you pay for ultimately.

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I have an Astronomik UHC filter. It's the only nebula filter I have used so I can't compare with other brands. However, it definitely improves the view of all emission nebulae I have observed with it - M42 and the Crab included. The main difference using the filter is twofold - it increases the contrast with the background sky, and it seems to bring out more structural detail. This first characteristic was invaluable when I was trying to observe the Eagle nebula, which I literally could not see without the filter. I have only used it in skies with moderate to low light pollution, so I cannot speak to how it would help if you were in an area with higher light pollution. 

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I can definitely give another thumbs up for the Astronomik UHC visual filter. I initially bought a Svbony UHC beforehand but on comparing the two I decided to sell the Svbony. It's a must for me when viewing M42 and other emission nebulae. This along with the Astronomik OIII enhances my viewing opportunities. Perhaps I should also add the H beta from the range as well.

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14 hours ago, bosun21 said:

I can definitely give another thumbs up for the Astronomik UHC visual filter. I initially bought a Svbony UHC beforehand but on comparing the two I decided to sell the Svbony.

Was it night and day difference, or was it more subtle?  I've found the difference between my 1990s Lumicon UHC and my Svbony UHC to be subtle.  Both improve the image because the Lumicon rejects more background sky glow.  However, it is subtle and not mind blowingly better.  Stepping up to my 1990s and modern Lumicon OIIIs does show a massive increase in contrast in comparison to either UHC.

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19 hours ago, Moonlit Night said:

Of all the UHC filters I have used my Tele Vue BandMate II Nebustar  is by far the best. Baader also makes excellent filters and have had great success with their Oiii filters, although since I only use a small refractor I now only use the Tele Vue BandMate II Nebustar filter, in fact it is the only filter I use these days. I would personally avoid cheap filters, you get what you pay for ultimately.

Baader's O-III filter is so narrow it only picks up the 500.7nm O-III line and excludes the 495.9nm O-III line.

Visually, this can result in great contrast for the small bright details, but at the sacrifice of size, as the outer parts of O-III nebulae are fainter, and the 25% of O-III light you sacrifice with a single line filter

means it will usually not show the full extent of the nebula.

That's why single line O-III filters are usually considered photographic O-III filters, where getting more nebula just means more exposure, while two-line O-III filters are considered visual O-III filters.

I experimented with O-III filters from 8.5nm bandwidth to (hard to imagine) 28nm (!) bandwidth, and discovered the really good ones picked up both O-III lines and had bandwidths of 11.5-13nm

The 15-18nm bandwidth filters didn't yield the contrast or the full extent of the nebulosity.  Needless to say, the ones in the 20-28nm range were simply close to having no filter at all.

For O-III, I've seen great results with:

Astronomik O-III 12nm (2017 on)

Tele Vue BandMate II O-III (2018 on)

Lumicon O-III (2005-2011, 2018-2022)

Edited by Don Pensack
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30 minutes ago, Louis D said:

Was it night and day difference, or was it more subtle?  I've found the difference between my 1990s Lumicon UHC and my Svbony UHC to be subtle.  Both improve the image because the Lumicon rejects more background sky glow.  However, it is subtle and not mind blowingly better.  Stepping up to my 1990s and modern Lumicon OIIIs does show a massive increase in contrast in comparison to either UHC.

It wasn't a massive difference between them but I found that when observing M42 the lines defining the nebulosity were sharper with the Astronomik UHC. Subtle sums the difference nicely however it was noticeable.

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By way of comparison, my Zhumell OIII is terrible as an OIII filter.  I finally figured out why when I looked at its spectrogram (see my LP Filter thread linked above).  It's right shifted so much that it barely captures one of the two OIII lines.  However, it nicely captures the carbon lines associated with green comets around 511nm (and possibly 514nm), so it makes for a wonderful comet filter.  My two Lumicon OIII filters make green comets disappear, so OIII filters don't normally make for good comet filters.

I just don't want people thinking the Svbony falls into that same category that the Zhumell falls into.  It's better than nothing as a nebula filter if funds are limited.

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One of the least effective UHC filters that I tried was the Explore Scientific. I don't know what it's band pass looks like but the Astronomik UHC and even my elderly Meade 4000 Narrowband made a much more obvious difference to the contrast and extent of the nebulae I tried them on.

I was slightly surprised by this. Most of the other Explore Scientific stuff that I've used has been pretty decent. And they do supply the filter in a very impressive and somewhat over-large decorated and foam filled box as well as the nice little plastic case. Perhaps they should have spent some of their packaging budget on a more effective filter ?

 

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Having tried most, I’ve settled on the DGM NPB and the Televue (by Astronomik, I think) OIII filters.  I concur with @John that the relatively inexpensive Explore Sci ones are comparatively ineffective.

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18 hours ago, John said:

One of the least effective UHC filters that I tried was the Explore Scientific. I don't know what it's band pass looks like but the Astronomik UHC and even my elderly Meade 4000 Narrowband made a much more obvious difference to the contrast and extent of the nebulae I tried them on.

I was slightly surprised by this. Most of the other Explore Scientific stuff that I've used has been pretty decent. And they do supply the filter in a very impressive and somewhat over-large decorated and foam filled box as well as the nice little plastic case. Perhaps they should have spent some of their packaging budget on a more effective filter ?

 

The ES filters have too wide a bandwidth to be effective:

Explore Scientific CLS Broadband Wide 100nm bandwidth
Explore Scientific H-Beta H-Beta Wide 18nm bandwidth 
Explore Scientific UHC Medium Band 48nm bandwidth
Explore Scientific O-III O-III Wide 18nm bandwidth
Explore Scientific O-III O-III Photographic 6.5nm bandwidth (1 line)

 

The H-ß is about twice as wide as it needs to be.

The UHC is closer to a broadband than a narrowband, also about twice as wide as it should be.

The O-III visual is too wide for effectiveness.

And the O-III photographic is fine, but too narrow for visual use and only picks up one line.

The visual filters are cheap Chinese filters and should be avoided.

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