SHO Filter for OSC Camera

Hi!

Any recommendations for a narrowband filter for the ZWO ASI2600MC camera?

I am seeking a SINGLE filter that has 3nm bands in sulphur, hydrogen and oxygen, 2" filter.

Thanks,
Jerry

From what I know there are no such duo-/tri-band filters as I suggest it’s technically not possible to separate Ha (651nm) & Sii (672nm) signal with one single coating… also it’s not possible to separate afterward Ha & Sii channels from RGB data to do SHO processing because the photons will be all registered into the same RGB bayer pattern pixel.

Ha and S2 are both red light… if you used a filter that collected both at the same time, you would not be able to separate them. The only filter that I am aware of that collects both s2 and Ha along with H beta (blue light) and O3 (teal light) is the Triad ultra.

If you want to capture true SHO data with a OSC, you'd need 2 filters. Askar has a set out of two different duo filters, one filter collects Ha and O3, the other collects S2 and O3. Something like that would be your best bet.

James:
Ha and S2 are both red light... if you used a filter that collected both at the same time, you would not be able to separate them. The only filter that I am aware of that collects both s2 and Ha along with H beta (blue light) and O3 (teal light) is the Triad ultra.

If you want to capture true SHO data with a OSC, you'd need 2 filters. Askar has a set out of two different duo filters, one filter collects Ha and O3, the other collects S2 and O3. Something like that would be your best bet.

Yes, you are right. But they are all +/- 40nm…? I he want’s to go that narrow there is no other option than single narrowband filters?

James:
Ha and S2 are both red light... if you used a filter that collected both at the same time, you would not be able to separate them. The only filter that I am aware of that collects both s2 and Ha along with H beta (blue light) and O3 (teal light) is the Triad ultra.

If you want to capture true SHO data with a OSC, you'd need 2 filters. Askar has a set out of two different duo filters, one filter collects Ha and O3, the other collects S2 and O3. Something like that would be your best bet.

Yes, you are right. But they are all +/- 40nm…? I he want’s to go that narrow there is no other option than single narrowband filters?

Triad ultra is 5nm Ha, 4nm on the rest of them.

The Askar duo NB filters are 6nm.

So no 3nm options exist.. but 4nm-6nm is not far off.

He specifically asked for one filter.. not sure if he's aware that Ha and S2 data couldn't be separated with a single filter.

The only filter filter I know of that can meet your requirements seems to be the Triad Ultra Quad band filter.
Very expensive, but in my opinion, worth the money and I do all my imaging with the filter.

The radian triad ultra quad band filter is not 3nm, but close. 4nm-5nm and it seperates Ha, Hb, OIII,and SII
https://optcorp.com/products/radian-telescopes-2-inch-triad-ultra-filter
Steve

Steve Cooper:
The radian triad ultra quad band filter is not 3nm, but close. 4nm-5nm and it seperates Ha, Hb, OIII,and SII

To be very clear - that filter will not separate SII and Ha into two separate channels in the OSC. The combined Ha+SII will be recorded in the OSC's red channel. H-beta will be recorded in the blue channel and OIII in green

True SHO imaging requires separate Ha, SII, and OIII data - which the triad filter will not provide.

As James pointed out - no single filter can physically separate SII and Ha into two separate channels for an OSC - if that in fact is that the OP is asking for. If he simply wants to capture Ha and SII data without bothering to separate them, then the triad will do that.

Roy Hagen:
The only filter filter I know of that can meet your requirements seems to be the Triad Ultra Quad band filter.
Very expensive, but in my opinion, worth the money and I do all my imaging with the filter.

I just looked at your gallery, very impressive. Do you use this filter on galaxy images also?

Steve Cooper:
Roy Hagen:
The only filter filter I know of that can meet your requirements seems to be the Triad Ultra Quad band filter.
Very expensive, but in my opinion, worth the money and I do all my imaging with the filter.

I just looked at your gallery, very impressive. Do you use this filter on galaxy images also?

Yes, I have until now used this filter on galaxies, but I recently bought a light pollution filter from Idaz to try out on galaxies.
R

Thanks all for your input. I don't want to spend over $1000 for a filter. I am using the Optolong L-Enhance filter which works pretty well. I am thinking about getting the L-Ultimate filter.

What I want to do is get better multiple colors without having to shoot with a mono camera and expose in multiple filters. Once I started using a CMOS OSC camera I just don't want to shoot with anything else. I live in a Bortle 8 area, so controlling light pollution is also very important, it's my understanding that 3 or 4nm will do that better than 7 or 8nm narrowband.

Jerry

I use the L Ultimate with the 2600mc and it works great. If you use PI with Blanshans pixel math script for HOO normalization you can get very close to SHO.

Jerry Gerber:
Thanks all for your input. I don't want to spend over $1000 for a filter. I am using the Optolong L-Enhance filter which works pretty well. I am thinking about getting the L-Ultimate filter.

What I want to do is get better multiple colors without having to shoot with a mono camera and expose in multiple filters. Once I started using a CMOS OSC camera I just don't want to shoot with anything else. I live in a Bortle 8 area, so controlling light pollution is also very important, it's my understanding that 3 or 4nm will do that better than 7 or 8nm narrowband.

Jerry

If you already have the L-Enhance then the Askar D2 Sii/Oiii filter is what you want. The L-Ultimate or Antlia ALP-T would be slightly narrower than your current filter but anything that tries to capture Sii and Ha at the same time will just give you the same red and let in more light pollution. You can't separate them unless you use 2 filters. Anything that is "more colourful" for example, Ray's excellent work, is all in the processing. Not from some magic from his filter. Here is a link to some work done by using the D2 in combination with filters like your L-Extreme.

https://app.astrobin.com/equipment/explorer/filter/10198/askar-colourmagic-d2-siioiii-duo-narrow-band-6nm-2

Roy Hagen:
The only filter filter I know of that can meet your requirements seems to be the Triad Ultra Quad band filter.
Very expensive, but in my opinion, worth the money and I do all my imaging with the filter.

Very impressive results, Roy - but "very expensive" descrives it well - but what would be cheap in astro photography :-)

By the way:
have you tried to use your color Asi2600mc with 3 narrowband SHO filters instead - what would be up- and downsides?

Jerry Gerber:
Hi!

Any recommendations for a narrowband filter for the ZWO ASI2600MC camera?

I am seeking a SINGLE filter that has 3nm bands in sulphur, hydrogen and oxygen, 2" filter.

Thanks,
Jerry

great question - would love to find a great solution to get better color seperation with my 2600mc without going into mono cams ...

As others have explained, with an OSC you will not get 'true' SHO, but it's possible to do a pretty decent job of extracting the various channels and combining them to produce something good.

I have the same camera as you and I use an Optolong L Extreme (7nm Ha and Oiii) then gather a separate set of data with the Askar D2 (6nm Sii and Oiii). You can see the results on my gallery. Most of them are with the L Extreme only, as I've only recently bought the Askar

Soul Nebula (combining two duoband filters)

Arny:
Roy Hagen:
The only filter filter I know of that can meet your requirements seems to be the Triad Ultra Quad band filter.
Very expensive, but in my opinion, worth the money and I do all my imaging with the filter.

Very impressive results, Roy - but "very expensive" descrives it well - but what would be cheap in astro photography :-)

By the way:
have you tried to use your color Asi2600mc with 3 narrowband SHO filters instead - what would be up- and downsides?

Good point, Arny. There is nothing cheap with this hobby.
I´ve never tried to run separate filters so I am not the expert to answer your question. I guess a mono camera would be more effective for that setup as it has no Bayer filter.
A friend of mine suggested that I should try a filter wheel and several narrowband filters as you thought of, but then, in my mind, the imaging will grow to be lot more complex.
I like to keep it simple
I´ve bought a Idaz light pollution filter for emission nebulae and galaxies that I will try to use in addition to the triad filter, and make the setup as simple as possible.

Roy Hagen:
I´ve never tried to run separate filters so I am not the expert to answer your question. I guess a mono camera would be more effective for that setup as it has no Bayer filter.
A friend of mine suggested that I should try a filter wheel and several narrowband filters as you thought of, but then, in my mind, the imaging will grow to be lot more complex.

I fully agree that "simpler is better", thats why I go with a Color Cam -
but you're touching something I can't get my head around:

- why does Bayer matrix of a color cam makes it less efeective?
I figured binning the color pixels would create similar mono "super"pixels which are more sensitive - but of course I loose details, ok.
Is there that wrong thinking?

- "imaging will grow to be a lot more complex" means, that taking 3x images for SHO is more complex?
or is there more to it I don't oversee?

Arny:
Roy Hagen:
I´ve never tried to run separate filters so I am not the expert to answer your question. I guess a mono camera would be more effective for that setup as it has no Bayer filter.
A friend of mine suggested that I should try a filter wheel and several narrowband filters as you thought of, but then, in my mind, the imaging will grow to be lot more complex.

I fully agree that "simpler is better", thats why I go with a Color Cam -
but you're touching something I can't get my head around:

- why does Bayer matrix of a color cam makes it less efeective?
I figured binning the color pixels would create similar mono "super"pixels which are more sensitive - but of course I loose details, ok.
Is there that wrong thinking?

- "imaging will grow to be a lot more complex" means, that taking 3x images for SHO is more complex?
or is there more to it I don't oversee?

Still I am not an expert, Arny.
Just a simple imager.
But if what I´ve understood is correct, the Bayer filter effective blocks certain wavelengths as S an Ha is red it would be blocked by green and blue, Hb and OIII is close to blue and green, so a red filter would more or less stop them. In a mono camera all pixels would collect those wavelengths.

And yes, in my mind, taking three images is more complex than one, or at least, as I see it.
Three sets of flats and dark flats, filterwheel, taking different sets of images over several nights where I live, with weather changes in minutes and three different possibilities to mess up.
This friend of mine, who is a mono imager, talks more often now about OSC and it`s advantages because he is a little fed up of the complex imaging process.

Well, in the end it pays off to do imaging the "complex" way as we rarely find OSC imagers among the IOTD winners.
This is only to clarify my thoughts and not a scientific approach, that would take experts like john Hayes and others.

If you want to separate the S, H and O channels there IS NOT any way to do so with any single filter on an OSC. Period. End of story.

You can certainly use multiple filters. There are some dual bandpass filters that are Ha and O3 and others that are S2 and O3. There are also the typical single filters that mono imagers use.

The purpose of those extremely narrow bandpass filters is to isolate specific wavelengths of light emitted by excited atoms. The most popular of which are the three I've already listed. You'll notice two of the wavelengths fall in the red spectrum and one falls in the green/blue (it's teal). By definition, you are NOT going to get "natural" colors from them. The Hubble palette creates an image by mapping from longest to shortest wavelength into R, G and B channels. Thus, S is mapped to red, H to green and O to blue. It is a false color palette. As are every other combination like HOO.

If you want "natural" colors, then your best bet is to use no filter at all and allow the entire visible spectrum of light through. Your camera's sensor is built to mimic the color response of our human eyes.

I use this analogy a lot to describe how filters work. Imagine a rainbow. That is our visible spectrum of reds, oranges, yellows, etc. Filters block parts of that. So, if you take a picture of a rainbow with no filter and that OSC, you'll get what you'd expect: red, orange, yellow, etc. Put on a filter like the Radian Triad Ultra and well, you're only going to get a bit of red and some blues and teal. A typical light pollution filter tends to knock out a lot of orange and yellow (because that's where the sodium and mercury vapor streetlights emit). Another funny looking rainbow. Some filters are better than others at preserving most of the rainbow.

At the end of the day, a filter is not a magic bullet. None exists that will turn your Bortle 8 skies into Bortle 2.

Arny:
- why does Bayer matrix of a color cam makes it less efeective?
I figured binning the color pixels would create similar mono "super"pixels which are more sensitive - but of course I loose details, ok.
Is there that wrong thinking?

Arny - the Bayer matrix of an OSC is designed with terrestrial photography (RGB) in mind. For that purpose - pure RGB imaging - it is actually more efficient than a mono camera (neglecting light pollution). But for narrowband, we are only interested in specific wavelengths (eg. 656nm for H-alpha). The red Bayer filter, for example, only lets in ~80% of incident H-alpha light. When you add on top of that a second filter, you get efficiencies like 78%. Meantime, a high quality mono filter lets in 99% of the H-alpha light because there is no second Bayer filter to block it. That's a 21% advantage straightaway for mono. The other reason is that the blue pixels in the OSC primarily capture H-beta, which is a less important emission line in many cases. These two reasons are among those why many imagers who are not cost conscious, or are accepting of complexity, or are willing to pay for ultimate performance, will go with the mono option.

The other big advantage of the mono camera is the ability to capture luminance. It is the most efficient way to capture enough signal to go deep on faint objects. Most of my RGB images involve luminance capture and I cannot emphasize enough how big a difference this makes in practice.

At the end of the day, in most cases, astro imaging with OSC involves a series of compromises, some more important than others. There are just fewer compromises with mono, but it comes with significant increase in cost.

Have a look at the Hutech NBZ filter Ha & OIII A 10nm band-pass transmission less expensive than the TRIAD filter.

Also for fast focal ratio scopes the wider bandpass is more forgiving not having major blue halos around the prominent stars in the image

Joe Linington:
Jerry Gerber:
Thanks all for your input. I don't want to spend over $1000 for a filter. I am using the Optolong L-Enhance filter which works pretty well. I am thinking about getting the L-Ultimate filter.

What I want to do is get better multiple colors without having to shoot with a mono camera and expose in multiple filters. Once I started using a CMOS OSC camera I just don't want to shoot with anything else. I live in a Bortle 8 area, so controlling light pollution is also very important, it's my understanding that 3 or 4nm will do that better than 7 or 8nm narrowband.

Jerry

If you already have the L-Enhance then the Askar D2 Sii/Oiii filter is what you want. The L-Ultimate or Antlia ALP-T would be slightly narrower than your current filter but anything that tries to capture Sii and Ha at the same time will just give you the same red and let in more light pollution. You can't separate them unless you use 2 filters. Anything that is "more colourful" for example, Ray's excellent work, is all in the processing. Not from some magic from his filter. Here is a link to some work done by using the D2 in combination with filters like your L-Extreme.

https://app.astrobin.com/equipment/explorer/filter/10198/askar-colourmagic-d2-siioiii-duo-narrow-band-6nm-2

I have got an D1 now and try to combine exposures taken with D1 and my LEnhance now, but struggle to process them properly in Pixinsight:
- extract RGBs from D1 and LEnh stacked subframes and Luminance from a combined D1+Lenh
- CombineRGB Red from D1, Green from D1, Red from LEnh, Luminance from a combined D1+Lenh

Result is not satisfying: red spikes nicely, but the rest looks like only taken with Lenh.

Any recommendations how to process differently?

Arun H:
Steve Cooper:
The radian triad ultra quad band filter is not 3nm, but close. 4nm-5nm and it seperates Ha, Hb, OIII,and SII

To be very clear - that filter will not separate SII and Ha into two separate channels in the OSC. The combined Ha+SII will be recorded in the OSC's red channel. H-beta will be recorded in the blue channel and OIII in green

True SHO imaging requires separate Ha, SII, and OIII data - which the triad filter will not provide.

As James pointed out - no single filter can physically separate SII and Ha into two separate channels for an OSC - if that in fact is that the OP is asking for. If he simply wants to capture Ha and SII data without bothering to separate them, then the triad will do that.

Exactly - you need 2 filters minimum for an OSC to capture both Ha and Sii (assuming you want to do SHO processing). The Antlia duo-band 5nm filters are really good, and would provide Ha & Oiii (1 filter) and Sii and Hb (2nd filter).

This topic is exactly my concern, wanted a 3nm one filter for SHO, but only dual band for 3nm from two brands, and one being said it is not actual 3nm as well.

In all cases, i don't how good Ha and OIII 3nm from this filter with OSC camera compared with let's say Ha 7nm or OIII 6nm with mono doing say double exposure time with OSC than mono, for example 4 hours OSC + dual band and 2 hours of each Ha and OIII with mono [or even 1 hour each to make total 2 hours for both together] for comparison, under Bortle 8/9.

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