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Space Oddities

Dual-band, tri-band, quad-band nebula filters

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Hello!

I was trying to get more information on the rather new "nebula filters", and I thought it would be interesting to share my findings into a Google spreadsheet :)  

I haven't included filters with a broader band pass, like the IDAS LPS V4 or some of the CLS CCD filters, which I believe are a different kind.

Also, regarding the FWHM, it reflects what the manufacturer officially claims. In the case of the STC Duo, it's unclear and I've seen different versions (10 and 12nm, 80 and 90% transmission). So, take it with a grain of salt :) 

Hope that helps!

363873377_Screenshot222.thumb.jpg.022747af1b43df8d786e2589e3149549.jpg

Here are the links to the manufacturer's website:

Edited by Space Oddities
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Anyone knows if  any of these filters or similar come in size of 36mm unmounted ?

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On 17/01/2020 at 18:47, Nikolas74 said:

Anyone knows if  any of these filters or similar come in size of 36mm unmounted ?

As far as I know, they don't :( Mounted 1.25" and 2" filters seem to be the most standard sizes for all of these, if not the only available.

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What about the Astronomik UHC as it is like the optolong l-enhance?

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Posted (edited)

We would need some decent with+without pictures to decide what they're worth...

EDIT: looks like it all depends on the amount of light pollution at your site: the more LP, the tighter the filter bandwidth has to be and the more $$$ we have to pay. Best, U.

Edited by uhb1966

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This is a v useful thread, thank you Space Oddities.  I'm going to move to a cooled camera, and was going for a cooled OSC & then thought maybe mono (but that would be more expensive w filters etc). Then heard about tri-band filters and found this thread!  Will stick to cooled OSC w one of these filters I think.  Happy-kat's idea of the Astronomik UHC sounds the most appealing - I think it needs to be used with a UV-IR filter as well. But since I have that already for a solar mod, it means just a UHC filter needed :)

Cheers & stay safe all!

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On 05/06/2020 at 09:15, vineyard said:

This is a v useful thread, thank you Space Oddities.  I'm going to move to a cooled camera, and was going for a cooled OSC & then thought maybe mono (but that would be more expensive w filters etc). Then heard about tri-band filters and found this thread!  Will stick to cooled OSC w one of these filters I think.  Happy-kat's idea of the Astronomik UHC sounds the most appealing - I think it needs to be used with a UV-IR filter as well. But since I have that already for a solar mod, it means just a UHC filter needed :)

Cheers & stay safe all!

Yep, there is a still a big argument that if you want the absolute best quaility, mono with narrowband filters is the way to go. But for me in the limited clear skies we tend to get, OSC with a dual/tri band pass is too much convenience to ignore. I cant be bothered (to be honest) shooting multiple flats, refocusing etc for each filter.

I prefer just one filter, press go and come back at the end of then night when its done :)

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On 08/06/2020 at 19:33, CloudMagnet said:

Yep, there is a still a big argument that if you want the absolute best quaility, mono with narrowband filters is the way to go. But for me in the limited clear skies we tend to get, OSC with a dual/tri band pass is too much convenience to ignore. I cant be bothered (to be honest) shooting multiple flats, refocusing etc for each filter.

I prefer just one filter, press go and come back at the end of then night when its done :)

Me too! Also sth to think about: the very best filters with bw's of 3 nm cost at least 1000 a pop x3 colors =>3 Grands for the hubble palette!

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On 08/06/2020 at 18:33, CloudMagnet said:

Yep, there is a still a big argument that if you want the absolute best quaility, mono with narrowband filters is the way to go. But for me in the limited clear skies we tend to get, OSC with a dual/tri band pass is too much convenience to ignore. I cant be bothered (to be honest) shooting multiple flats, refocusing etc for each filter.

I prefer just one filter, press go and come back at the end of then night when its done :)

I guess I’m being lazy to not research this myself, but has anybody published a comparison of performance of a high end OSC with dual/tri band filter vs the traditional mono camera and separate filters?

I would be really interested to see what the trade off is in image quality vs convenience.

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Posted (edited)
On 08/06/2020 at 19:33, CloudMagnet said:

Yep, there is a still a big argument that if you want the absolute best quaility, mono with narrowband filters is the way to go. But for me in the limited clear skies we tend to get, OSC with a dual/tri band pass is too much convenience to ignore. I cant be bothered (to be honest) shooting multiple flats, refocusing etc for each filter.

I prefer just one filter, press go and come back at the end of then night when its done :)

Refocus: bear in mind that with mono you can, if you like. With OSC you can't. (My point is that good quality filters of the same make are parfocal. Non parfocality really comes from the optics, so with OSC you make a compromise focus because that's all you can do. You can make the same compromise with mono and filters if you like, or you can focus per filter if you prefer.)

Multiple flats: I use luminance flats for all filters.  What's the problem? In a sealed wheel bunnies don't come from the filters - in my experience.

Come back at the end of the night: you'll be very lucky to get away with no refocus during the night. Temperature change clobbers focus. If you focus robotically you can build that into your filter changes.

Olly

Edited by ollypenrice
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Don't really see why these filters need to be used with OSC camera?

Usage with mono is allowed and if I have something to say - encouraged :D

We use LRGB as imaging model - why not Multiband + H/OIII/SII model?

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Posted (edited)

@vlaiv: Yes, indeed you can. It gives you a light pollution type filter on your luminance.

What you cannot do is separating the channels, something what you can do on OSC - at least on a red (Ha+SII) and green+blue (OIII) and blue (Hb) level.

There is another quality that separates these filters, aside from bandwith.

And that is the effectiveness of anti-reflection coatings. I have used two of the filters mentioned and one of them has larger reflections around stars in my imaging system. It is difficult to give a general recommendation on this as you need to test filters in the same light train to compare (and also compare high speed systems with lower speed systems).  Given adequate funds and a bit of time, this would be a worthwhile addition to the price/benefit comparisons.

Edited by Annehouw

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On 18/06/2020 at 14:04, uhb1966 said:

Me too! Also sth to think about: the very best filters with bw's of 3 nm cost at least 1000 a pop x3 colors =>3 Grands for the hubble palette!

Dont forget buying the filter wheel as well. They can cost a fair bit as well.

On 18/06/2020 at 19:10, tomato said:

I guess I’m being lazy to not research this myself, but has anybody published a comparison of performance of a high end OSC with dual/tri band filter vs the traditional mono camera and separate filters?

Yes! Would love to see this.

23 hours ago, ollypenrice said:

Refocus: bear in mind that with mono you can, if you like. With OSC you can't. (My point is that good quality filters of the same make are parfocal. Non parfocality really comes from the optics, so with OSC you make a compromise focus because that's all you can do. You can make the same compromise with mono and filters if you like, or you can focus per filter if you prefer.)

Multiple flats: I use luminance flats for all filters.  What's the problem? In a sealed wheel bunnies don't come from the filters - in my experience.

Come back at the end of the night: you'll be very lucky to get away with no refocus during the night. Temperature change clobbers focus. If you focus robotically you can build that into your filter changes.

Olly

Yep, maybe I exaggerated just setting up and leaving it for the night :). I still think that Mono/narrowband is the best but the ease of use on OSC can't be ignored.

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@CloudMagnet Yep, narrowband gives the most dramatic images! But i like to see the stars as they are as well. Decisions!🤔

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2 hours ago, uhb1966 said:

@CloudMagnet Yep, narrowband gives the most dramatic images! But i like to see the stars as they are as well. Decisions!🤔

In theory there is no reason one can't have both, taking some RGB frames along with your narrowband and using starnet++ to extract the stars from them and pixelmath them into the narrowband images. Planning on trying this myself over the next week with the veil nebula.

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Posted (edited)

Sadly I cannot edit the original post, but Hutech announced a new filter, the IDAS NBX. It seems to be optimized to work with fast f/2 optics.

https://digiborg.wordpress.com/2020/06/29/new-idas-narrow-band-filter-nbx/

I can't edit the image, but the spreadsheet is updated!

Quote

We proudly announce a new IDAS dual narrow-band filter – NBX, which is scheduled to be commercially available at following sizes early of August.

NBX-48 : $299.00

NBX-52 : $299.00

NBX at 300 to 1200nm

Features :

  • 10nm bandpass for Ha and OIII respectively.
  • IDAS-proprietary “flat-top”, “steep cut-off” and “off-center” design eliminates the emissions’ signal loss due to the spectrum shift until F2 speed.
  • Available 48mm and 52mm mounted (2.5mm thickness)
  • No IR blocker required
NBX at 400 to 700nm

Spectrum shift at F2

comparison

Left : on-axis & Right : F2 cone

 

As shown above, NBX maintains original transmission rate even the spectrum shift occurs while the conventional design dramatically looses the emission signal. They are still 10nm vs 7nm comparison. But we should consider at the viewpoint of S/N ratio.

 

Edited by Space Oddities
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Posted (edited)

New Filter is available, Optolong L-eXtreme, (7nm H-alpha and O-III)

 

Must be also very interesting..

 

REgards

 

Martin

Edited by artem

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Quick example of Optolong L-eNhance image. Cygnus Loop, RASA8/Zwo ASI071MC Pro. 158 x 40" Gain 95, 80% Moon

My reason for using the filter is just for Moon compromised nights as I am in Bortle 3 and get great definition and colour with an OSC.

This was developed in StarTools using 3 channels in the Compose mode and RGB:RGB preset 'colour' with minor adjustment.

Cygnus Loop3Channel.jpg

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