see
http://www.astrosurf.com/buil/filter...#Lumicon%20UHC
and
http://www.lumicon.com/images/2.htm and
http://www.lumicon.com/images/1.htm .
Astronomik UHC passes more Ha than Lumicon Ha .
Lumicon DSF looks superior to both if you want Ha too.
Want to cut Hg emission bands at 405, 436, 546 and 579 nm
and airglow at 558 nm ,
and Na emission bands at 570, 583 ,600 and 617 nm. Lumicon Deep Sky Filter fits the bill and still passes broad bands.
I wonder how the Hutech drop LPFs compare ? append ...
http://www.sciencecenter.net/hutech/idas/filtdata.htm . Looks like these pass a bit of Na 570 and 600 nm and airglow 558 nm.
append added
http://www.astronomik.com/english/eng_uhc-e.html
http://www.astronomik.com/english/eng_uhc.html
http://www.astronomik.com/english/eng_cls.html ...looks to best of this 3.