Fordos Moon Posted January 21, 2015 Share Posted January 21, 2015 Afternoon All.Soon I will be getting a 9 position filter wheel.I have ZWO L/R/G?B filters already and intend to buy the Ha/OIII/SII and Hb filters.Question is, while I have the wheel open is it worth sticking in an IDAS LP filter and what would I use this for when I am doing either LRGB or narrowband imaging with the other filters?Many thanksKing of the Stupid Questions Link to comment Share on other sites More sharing options...
MattGoo Posted January 21, 2015 Share Posted January 21, 2015 My ZWO LRGB 1.25" filters don't fit in the Starlight Xpress USB filter wheel, the filter holders are too thick.I may have to swap them for some Astronomik or Baader ones. Link to comment Share on other sites More sharing options...
Fordos Moon Posted January 21, 2015 Author Share Posted January 21, 2015 Thanks Matt I'm looking at the Atik EFW2 and I think it works okay for ZWO filters Link to comment Share on other sites More sharing options...
johnrt Posted January 21, 2015 Share Posted January 21, 2015 I have all my filters, LRGB and Ha / OIII stacked behind a 2" IDAS LP2 which is left in place for everything. Works wonders for my broadband imaging and doesn't effect the narrowband so I just leave it in place and forget about it. 1 Link to comment Share on other sites More sharing options...
Starflyer Posted January 21, 2015 Share Posted January 21, 2015 I have 9 filters in my EFW2 including the IDAS LP filter. I haven't opened it since installing them and there's no dust visible in flats from any filter.I use LRGB when I have dark skies and LP RGB for normal use where I have some LP..I don't use a LP filter in front of everything because it will cause some light loss even with the NB filters and every photon counts 1 Link to comment Share on other sites More sharing options...
johnrt Posted January 22, 2015 Share Posted January 22, 2015 I don't use a LP filter in front of everything because it will cause some light loss even with the NB filters and every photon counts You're not wrong there is a little loss due to the IDAS in front of narrowband filters, but it is an insignificant amount, the LP2 passes over 95% of Ha, OIII & SII and I see no difference in my images with very narrow 3nm pass band filters. But for the purest, you are of course correct, remove it from the light path and you'll gain that extra little bit back. 1 Link to comment Share on other sites More sharing options...
Steve 1962 Posted January 22, 2015 Share Posted January 22, 2015 I have an IDAS in series with my filter wheel too. If I was you I wouldn't bother with Hb - I've got one and never used it. It just gives the same signal as Ha but fainter. Link to comment Share on other sites More sharing options...
Fordos Moon Posted January 23, 2015 Author Share Posted January 23, 2015 I have an IDAS in series with my filter wheel too. If I was you I wouldn't bother with Hb - I've got one and never used it. It just gives the same signal as Ha but fainter.Thanks Steve I did wonder of its purpose, FLO charge an extra £20 to have one included with the HA, OIII and SII package but i guess thats why its so cheap if it has little use could save myself twenty quid Link to comment Share on other sites More sharing options...
Starflyer Posted January 23, 2015 Share Posted January 23, 2015 Hb is a distinct wavelength at the other end of the spectrum to Ha, think Ha = red and Hb = blue.There aren't a huge number of targets that emit much light in Hb, so I can see why these would be viewed as pretty much useless. There's a list of targets here, the page refers to visual astronomy but I don't see why the list shouldn't be valid for imaging.Saying that, I've never used mine Cheers,Ian 1 Link to comment Share on other sites More sharing options...
Steve 1962 Posted February 2, 2015 Share Posted February 2, 2015 (edited) Ian's absolutely right about Ha being red and Hb being blue. The point I was trying make is that they're both generally the same cloud of Hydrogen gas in different states of ionisation. Edited February 2, 2015 by Steve 1962 1 Link to comment Share on other sites More sharing options...
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