Selecting Ha Filter

[Hans Tucker]

Is there a particular rule for selecting a Ha Filter of particular Bandwidth?

I note you can purchase filters from 3nm through to 12nm. Does a 3nm take more skill to image through than a 5nm or 7nm

[Hagar]

From where I sit Hans the extra skill is involved in focusing. Less and smaller stars make it very hard. The other thing is the lower the band pass the more exposure time required to get an image and also to focus it.

[Bolts_Tweed]

Gday Hans - I'll have crack at it

People have their own preferences but as I understand it - 3 nm = narrower section of the spectrum = longer exposures on fainter objects but also = higher contrast. I have heard of people having focusing problems but I suspect that might be with DSLRs and focusing visually - oh yeah good quality = good dollars they cost more to get a good one See Astrodon 3nm for example - I used to pay that for a scope but again they are quality gear.

I use 6 nm Astronomik - double spectral range but still fairly high contrast - still a bit expensive to get a good one - i've never had any drama focusing - a 1 second exposure on a 4th mag star is fine with my camera and scope.

I have even used a 12 nm visual Ha filter - ok if you are starting out but might be a waste of time. Advantage - cheap. Nah stay away from em

I am sure others have more experience and technical knowledge but this is my experience.

Mark Bolton

[jase]

Contributed to numerous threads on this topic before;

http://www.iceinspace.com.au/forum/showthread.php?t=41935

http://www.iceinspace.com.au/forum/showthread.php?t=31029

http://www.iceinspace.com.au/forum/showthread.php?t=28505

If these don't answer a specific question, I'm sure someone can jump in and provide the needed guidance.

[Hans Tucker]

Thanks Doug and Mark for your input and Jase for the links..some excellent information. :thumbsup:

Sorry for resurrecting another previously discussed topic

[Tandum]

How much do you want to pay? My baader 7nm gives me the results I want but in my opinion it was really expensive for a piece of glass.

[Hans Tucker]

Cost is not a factor for me but quality is. I don't want to get into the SII OIII area of Narrowband imaging but I would like to understand Ha better in order to make the right filter selection.

[Tandum]

In that case get a selection and test them :D