Helix Nebula

[gregbradley]

I haven't used an Astronomics Ha filter. I have Baader 7nm and Astrodon 5nm. The Astrodon is quite a bit better but I wonder if I just got a bum Baader. It often gives black specs in the images whereas the Astrodon does not. The Astrodon gets better detail but its not a massive gain.
Ha coatings are apparently hard to do and can be affected by humidity etc. The coatings on my Baader look a tad speckled.

If you image from a dark site the narrower bandwidth the better is the usual formula.

Greg.

[AlexN]

Paul - I'd go for Astrodon or Custom Scientific... I've got a set of 5nm custom scientific NB filters coming shortly... Its very much a game of you get what you pay for when it comes to filters... Baader LRGB filters are actually quite good... but for narrowband I went for the best I could afford... and as narrow as I thought my exposure duration could manage... with your mount, don't be affraid to go for a 3nm Ha filter!

[Paul Haese]

Thanks guys, will chase this up a bit more. More reading. Thanks.