Which 1.25" Ha filter for imaging?

[Astronutjob]

As above what the best wavelength to go for? When imaging in mono?

[davew]

Do you mean wavelength or band pass ? If the latter I'd go for the narrowest you can.

You can buy them in 3,5,6,7,12 and 35 nm as far as I recall. I got 5nm but they're expensive. The Astronomic and Baader filters look good value. My preference would be Baader if it'll fit the filter wheel / holder you want to use. They have a raised edge that's very tall.

Dave.

[swag72]

I use the Baader 7nm Ha filter and it works well. However I've become something of an Ha junkie and so I'm going to get a 3nm Astrodon later in the year. The 3nm should be better in full moon situations and will increase the contrast in general.

[RikM]

Baader 7nm for me too.

[Astronutjob]

What would the difference be between a 3nm and 12nm say image wise? Is that the 7nm baader one for about £100?

[Freddie]

7nm for me as well. £109 from FLO.

[Astronutjob]

What do you think of this deal? have settled on getting the 7nm Ha one, but what about the Oiii and Sii bandpass? are they the most popular?

http://www.firstlightoptics.com/narrowband/baader-narrowband-ccd-emission-line-h-alpha-filters-125.html

[davew]

I think it's a very good deal in so far as you, in effect, get a free filter. I wouldn't buy an Hb filter but if someone gave me one I'd have it

Re 3nm to 12 nm. There is less unwanted light passed by the tighter filter. This can make a big difference during the Moon pollution period. It can also give a slightly higher contrast.

The only downside I can see to having a greater band pass with the O111 filter is that you may get larger stars in the O111 layer. However, for the price, you can sit at the computer and reduce those stars.

Dave.

Edit. The world needs more Ha junkies.

[Tim]

What camera have you got?

7nm will probably be too harsh for a DSLR, but for a mono camera the Baader 7nm really rocks I use mine in full moon conditions with a mono camera.