DSO Imaging in NII - what's available?

[Gina]

This morning I almost bought an NII 3nm Astrodon filter from Ian King - a whole £500 inc. postage!  I think if PayPal had been available I would have gone ahead but I needed my debit card so paused for thought.  I'm keen on trying things that most other astronomers don't and this is interesting.  I know of two or three nebulae that have quite strong NII emissions but are there enough to make it worthwhile?  I know this is a personal decision but wondered if there was a list of DSO emitting the NII wavelength. 

I already have Ha, OIII and SII 3nm filters plus 5nm Ha and SII.  The 3nm Ha is superb and I'm very pleased with it.  SII less so - maybe a mistake.  I've been Googling but not found a lot. 

This is a low light pollution site and I have an observatory (for those who didn't know).  My current main imaging rig is shown in my signature but I also have many other focal length lenses plus Esprit 80ED Pro and MN190 Pro scopes.

Any information would be much appreciated - thank you

[PatrickGilliland]

Hi Gina

I would save your money for now.  If you don't know what you want it for I would park it.  I own one and have not used for over a year!

For nebula work some do have high NII output but consider this - @5nm you are picking up some NII anyway.  If you had another mono channel would you know how to blend and in what ratios?  If you image with HA > 3nm I.E. your 5nm you pick up the additional NII and this is naturally blended into you data with no extra effort.  Targets such as NGC 7822 have masses of NII but you would be very hard pushed to tell any difference in the data from Ha other than marginally weaker signal.  I struggled finding as use for the data even when I did have.  If you was operating at longer FL and going after PN's that might be a different topic as some PN's have distinct NII features that would offer a real different view.

Unless you have a clear 'mission and purpose' I would not worry about.  If your target has NII stick the 5nm filter in and pick up the free NII you get that way to further reinforce you Ha signal and detail.  I am more interested in getting my i-sloan filter than then NII which is now out of the FW!

Hope that helps

 

Paddy

 

[Gina]

Thanks Paddy   No hurry really anyway - I have plenty of stuff to image   I do have scopes for longer focal length to suit PNs but ATM I'm exploring widefield.  May find something better to spend half a grand on

[PatrickGilliland]

10 hours ago, Gina said:

Thanks Paddy   No hurry really anyway - I have plenty of stuff to image   I do have scopes for longer focal length to suit PNs but ATM I'm exploring widefield.  May find something better to spend half a grand on

Welcome Gina - maybe revisit the no guiding route?  I nice guidecam set up <£500 and will increase that signal.....

Paddy

[Gina]

I already have all the kit needed for guiding and I shall certainly be guiding the Esprit 80ED.  This will be using the SX EFW with built-in OAG.  I may also guide the 200mm f4 lens which is not only nearly twice the FL but more than a stop slower.  May want 4m subs with that which might strain the PA.

[Gina]

Another possibility for the future might be a dual rig setup.  This could be either two imaging rigs side by side on the one mount or possibly two mounts.  I might keep one of my Atik 460EX cameras to leave my options open   So much to do - so little time!