Light Pollution Filter Recommendations

[scitmon]

Hi all, I've been looking into getting a light pollution filter for my setup for the upcoming dark nights and would appreciate some recommendations on what to get. 

My setup is a Skywatcher 80ED DS-Pro -> FF/Reducer -> Modded Canon 700d under Class 5 Bortle skies.  I think my light pollution is a mixture of LED street lamps and the old style ones but I can't be certain what the dominant light frequencies are.

I am also planning to move to a dedicated astro mono camera with filter wheel one day so in an ideal world I would like it to be compatible with that is possible (so avoiding clip in filters if poss).

[vlaiv]

2" IDAS LPS - in some variant, either P2 or D2

P2 is better if you don't have much LED lighting around, and D2 is their latest, supposedly designed with LED in mind.

Don't go for 1.25" variant, as you will have trouble with that size of sensor, and 2" will be usable when you switch to mono and filters - you will need to "stack" filters, so 2" can be mounted forward in optical chain, and regular filters next to sensor. I use 2" and 1.25" with mono myself.

[scitmon]

Chosing between the P2 or D2 is tricky.  I do see a red shift to all my pictures, would that suggest that my light pollution is mostly from old style sodium lamps?  Which would make the P2 the better choice?

[Hailfire101]

I have the IDAS P2 and I can't fault it. I do live in an area which has been updated to LED lighting too, so it was the one to go for. 

I've only used it with a DSLR camera though. I'm hoping to go narrowband soon, to avoid LP even more. 

[vlaiv]

I think that red shift can come from both. I'm not sure what is the best way to diagnose dominant type of LP. My sky has orange tint to it visually (edge between red and white zone, so Bortle 7 or 18.5mag), or to put it in another words, when cloudy, clouds look grey-orange, and P2 helps quite a bit.

Here is spectra of common types of street lighting:

As you see, red part of spectrum is covered in most cases, so not sure how could you judge what type of LP is dominant.

Can you go to higher ground and survey area visually? Just look at brightest light sources, those that are exposed to sky - not ones that have proper shielding - their impact will be smaller, maybe take note count that you can see. If yellow / orange - put towards HPS/LPS count, if bright/cool white - put towards LED count.

If you happen to have StarAnalyzer or alike - maybe you can use that to identify sources - bring it to your eye and look through it, you should be able to see spectra and identify source - not sure if you can do sky measurement with it to produce actual sky spectra though.

[scitmon]

If that's the case I think the D2 is the way to go because locally my street lamps are LED. 

Thank you for the input.