Narrow band filter ratio

[simmo39]

Hi all, just a quick question, is there a ratio of time between different filters to get a good narrow band image? So far I have only used my Ha and Oiii. On the project I'm working on at the moment I have done 25 X 240 for the Ha and 25 X 300 for the Oiii. If I get chance this week I will be trying out the Si filter and I'm not sure how much data do I need compared to the other filters. Ant thoughts? 

[Adam J]

3 minutes ago, simmo39 said:

Hi all, just a quick question, is there a ratio of time between different filters to get a good narrow band image? So far I have only used my Ha and Oiii. On the project I'm working on at the moment I have done 25 X 240 for the Ha and 25 X 300 for the Oiii. If I get chance this week I will be trying out the Si filter and I'm not sure how much data do I need compared to the other filters. Ant thoughts? 

Its totally target dependent.

[kirkster501]

Yes, it is target dependent.  That said there are some general rules and of the three Ha is the easiest to collect followed by Oiii.  Si ( you mean SII ??? ) is so faint and requires so much data and time that in UK skies it is generally not feasible and hence bicolour narrowband is very popular where you do Blue and Green with OIII and Red with Ha. Other combinations of OIII and Ha can also be used. 

You may find this thread of interest.

Steve

https://www.cloudynights.com/topic/551868-signal-sanity-check-sii-vs-oiii-ha/

 

[simmo39]

1 hour ago, Adam J said:

Its totally target dependent.

Hi Adam, Im doing the Elephant trunk, the bi image looks ok but i would like to get Sii data.

 

27 minutes ago, kirkster501 said:

Yes, it is target dependent.  That said there are some general rules and of the three Ha is the easiest to collect followed by Oiii.  Si ( you mean SII ??? ) is so faint and requires so much data and time that in UK skies it is generally not feasible and hence bicolour narrowband is very popular where you do Blue and Green with OIII and Red with Ha. Other combinations of OIII and Ha can also be used. 

You may find this thread of interest.

Steve

https://www.cloudynights.com/topic/551868-signal-sanity-check-sii-vs-oiii-ha/

 

Hi Steve, yep meant Sii. thanks for the link. Im just trying to find out if the Trunk is Sii rich.

[Adam J]

I don't even own an SII filter. So can't advise. I don't own one because I nearly get to to do two channels per target in the UK. 

[ollypenrice]

If you want to present an image with the 'right' distribution of gasses you could always take the dominant one, usually Ha, and give it the stretch it will take while recording this as an action. You could then play that action on the other filters' images to see what the noise looked like and add more time as necessary. In reality I doubt that many amateurs are trying to replicate the object's relative intensities.

Olly

[simmo39]

2 hours ago, ollypenrice said:

If you want to present an image with the 'right' distribution of gasses you could always take the dominant one, usually Ha, and give it the stretch it will take while recording this as an action. You could then play that action on the other filters' images to see what the noise looked like and add more time as necessary. In reality I doubt that many amateurs are trying to replicate the object's relative intensities.

Olly

Hi Olly, Thats more or less how I was going to play it. I never give enough time to any target to get real good results as there seem to be so few nights when im not tired or clouded in. I was just hoping for that special formula that works every time out of the box. My new asi 1600mm is very impressive to these eyes I just wish I could maximise the results. Hopefully will get a clear night this week and get some Sii data. I just want to see if I can do a reasonable  Hubble palette image.

[simmo39]

On 15/09/2018 at 19:33, Adam J said:

I don't even own an SII filter. So can't advise. I don't own one because I nearly get to to do two channels per target in the UK. 

I must admit after reading lots the Sii filter looks like a lot of hard work but now i have one I think I must at least give it ago.

[Adam J]

10 minutes ago, simmo39 said:

I must admit after reading lots the Sii filter looks like a lot of hard work but now i have one I think I must at least give it ago.

Some targets are better for it than others. For example I see lots of people do HSS for the California nebula and omit OIII. 

[simmo39]

1 minute ago, Adam J said:

Some targets are better for it than others. For example I see lots of people do HSS for the California nebula and omit OIII. 

I will have to look into this more, do you know if there is a reference which gives you details of which filters are better for which target?

[glowingturnip]

I'm currently in the middle of processing my first ever SHO image.  There's an excellent Pixinsight tutorial on combining the channels, whilst avoiding magenta stars, here - http://www.arciereceleste.it/articoli/translations/75-narrowband-color-composition-eng

From my *very* limited experience of narrowband, the Lagoon is good in Sii (though maybe a bit low and late in the year now), and the Eagle is rubbish.

[simmo39]

57 minutes ago, glowingturnip said:

I'm currently in the middle of processing my first ever SHO image.  There's an excellent Pixinsight tutorial on combining the channels, whilst avoiding magenta stars, here - http://www.arciereceleste.it/articoli/translations/75-narrowband-color-composition-eng

From my *very* limited experience of narrowband, the Lagoon is good in Sii (though maybe a bit low and late in the year now), and the Eagle is rubbish.

Hi Stuart. thanks for the link, Both Lagoon and Eagle are past there best for me. They will have to wait till next year.