Filters

[GrahamMc]

I joined Stargazers about 5 years ago, and while I haven't been an active contributor I have been actively stargazing. A few years ago I bought my first scope - Celestron 4SE - and now I am excitedly waiting on the delivery of a 10" Dobsonian. With the Celestron I also bought a set of planetary filters; my question is - does anyone know if these are suitable for objects beyond our solar system?

[Dave In Vermont]

I assume you means deep-sky objects - or DSO's - and the answer is not really. For these objects you would be well advised to read up on narrow-band filters and so-called nebula-filters. Representatives of these are the UHC and OIII-Filters, made by several different outfits with slightly different bandwidth cut-offs, as well as various different prices. Here's a couple of links to help untangle what this boils down to:

http://www.prairieastronomyclub.org/resources/by-dave-knisely/filter-performance-comparisons-for-some-common-nebulae/

And:

http://www.prairieastronomyclub.org/resources/by-dave-knisely/useful-filters-for-viewing-deep-sky-objects/

These are both written by David Knisely of the Prairie Astronomy Club in the US. David is a well-known authority on filters and how to employ them. And branching into the application of colour-filter we have these:

http://sas-sky.org/wp-content/uploads/2011/09/SAS-The-Use-of-Astronomical-Filters1.pdf

http://agenaastro.com/choosing-a-color-planetary-filter.html

This should give you a very good idea of what these can do and which types of objects may benefit the most for which. Most would agree that for DSO's, you'd be best off getting either a UHC-Filter or an OIII-Filter. Which to get first? Toss a coin.

Hope this helps -

Dave, who has 35 of the little darlings scampering about in my astro-cases.

 

[GrahamMc]

Thank you very much. A quick browse of those sites tells me I need to go back and study them in more detail