Filters to match my situation.

[Entropy]

Hi everyone,

I recently purchased a SBIG STL 11000m to go with my FSQ106EDXIII (On an EQ8). My job will probably have me living in moderate to heavily light polluted areas at least for a few more years so I have decided to purchase a set of NB filters.
While I understand that buying a full set of 3nm filters is the absolute best way to cut through light pollution they're not in my budget at this stage.
I have been looking at something like this...
Link.
The person who sold me my camera suggested that around 7nm is a fairly good bandwidth to be using. My questions are.

Does it matter that all the bandwidths of these filters are slightly different, will that cause complications when stacking/combining?

Would holding out, continuing to save (for quite a while) for a 5nm set be significantly better or am I chasing 1%'ers at this stage? (Also noting that I have 0 filters for my camera at this stage)

Is Hb beneficial to have or is it more a nice if you've got it, will not miss it if you don't (ie. would I save money by buying the filters individually?)

Am I biting off more than I can chew by jumping straight from OSC unmodded DSLRs to NB imaging, should I just purchase a sset of LRGB filters and deal with light pollution until I get used to this new paradigm (Currently living in moderately light polluted area, Brisbane suburbia)?

Is there any other considerations I should be thinking of?

Note... At this stage I am using a separate guidescope and camera (SSAG) so no concerns about finding guide stars behind the filter... however I would like to at least try out OAG at some stage and understand that finding a suitable guidestar can be difficult behind filters, especially very narrow ones.

Thank you

Entropy

[glend (Glen)]

Have a look at the Baader Narrowband filter sets, i use them and they are excellent and are reasonably priced. Stick with the7-8nm filters, 3nm us just too small and you need a longer exposure to get the same results. Especially as your just starting, stick with the 7-8nm filters.The Baader filters are parafocal so you don't have to refocus between filters if you don't wish to do so. Forget Hb, all you need is Ha, Oiii, and Sii, and really most of your data will be Ha and Oiii. Don't forget that Oiii can be Moon affected due to its spectrum position, i try to shoot Oiii before the Moon rises, Ha anytime, but keep the moon away from the front of the scope if you can, 45 degrees is the minimum. Stick with a guidedcope until you have mastered NB imaging.
Re software i highly recommend SGPro for controlling your imaging sequence, very easy to setup your run, filter changes, etc.
Obviously you need to match your filter size to your filter wheel and type, many filter wheels use unmounted filters, so make sure you order the right type and size. I bought my Baader narrowband set from Teleskop-Express in Germany, good price for the set (they knock off the euro VAT tax for export to Aus), great service and fast shipping.Good luck.

[Entropy]

Thank you for your help.
There are some good deals on that site, and at quite good prices (Do you take 19% off their listed price?)
Something I didn't know, is that teleskop-express recommend not using 7nm filters, but use much wider ones, why is that? Is it really that much of an issue?

Thanks again

[RickS (Rick)]

Originally Posted by Entropy

I recently purchased a SBIG STL 11000m to go with my FSQ106EDXIII (On an EQ8).

The FSQ106 and STL11K is a nice combination. I used this pairing for a while.

Originally Posted by Entropy

Does it matter that all the bandwidths of these filters are slightly different, will that cause complications when stacking/combining?

Using NB filters with different bandwidths is not a problem.

Originally Posted by Entropy

Would holding out, continuing to save (for quite a while) for a 5nm set be significantly better or am I chasing 1%'ers at this stage? (Also noting that I have 0 filters for my camera at this stage)

5nm will be better and 3nm will usually be better still (see note below) but plenty of people get good results with wider bandwidth NB filters. If you'll have to wait quite a while for better filters then I'd be inclined to get what you can afford and give it a go.

Originally Posted by Entropy

Is Hb beneficial to have or is it more a nice if you've got it, will not miss it if you don't (ie. would I save money by buying the filters individually?)

I don't know of anybody who bothers with Hb. It is a lot dimmer than Ha so you'll need really long integration times to get decent SNR and you can simulate it with mixing red+blue to match your Ha.

Originally Posted by Entropy

Am I biting off more than I can chew by jumping straight from OSC unmodded DSLRs to NB imaging, should I just purchase a sset of LRGB filters and deal with light pollution until I get used to this new paradigm (Currently living in moderately light polluted area, Brisbane suburbia)?

If you're not committed then you may struggle but if you're willing to put in the effort you should be able to do it.

Originally Posted by Entropy

Is there any other considerations I should be thinking of?

Note... At this stage I am using a separate guidescope and camera (SSAG) so no concerns about finding guide stars behind the filter... however I would like to at least try out OAG at some stage and understand that finding a suitable guidestar can be difficult behind filters, especially very narrow ones.

Your hardware all sounds fine. A guide scope will be perfectly adequate at 530mm focal length so long as you have a reasonably rigid coupling. No need to consider an OAG for a short FL system like that.

Originally Posted by glend

Stick with the7-8nm filters, 3nm us just too small and you need a longer exposure to get the same results.

This is a misconception. Unless you are dealing with a very fast system (f/3 or faster) where the angle of the light cone causes spectral shift there is no benefit from a wider bandwidth filter. There is one exception to this: a 5nm Ha filter will pick up Nii as well as Ha so some planetary nebulae (the Helix is a good example) will give a stronger signal with 5nm than 3nm Ha filter.

Cheers,
Rick.