[Chaos-l] Narrowband filters?

[Robert Nielsen]

Yeah ... I don't ever remember not being able to focus with an O-III filter.   In fact, I specifically remember what 52 Cygni looks like using the filter ... it had a bluish tint, with some red around the edges when out of focus.    So you can at least see some stars with it!  In fact, I think you can see quite a few.

I agree with Michael ... the H-beta filter should be down on the list ... it just isn't that useful.   The O-III would be the first I would get (and it was!) ... and as Allen said, the Lumicon filters are the gold standard ... you can't go wrong with them.  I've seen some other Chinese-made O-III filters that didn't work nearly as well.   Since you'll only save a few dollars getting one from a different manufacturer, I would recommend the Lumicon.

I would get a polarizing filter to look at the moon second, then probably a UHC.   For me, the choice of the O-III or UHC depends on the target you are looking at (and the star field around it).   In some cases, the nebula is so faint that you can't really see it without blocking out all the other light.  But other objects, like Thor's Helmet (and it depends on the conditions and the telescope) can look better in the UHC.  Since it sits in the Milky Way ... seeing the stars frame the object better.   I've seen the Crescent Nebula in Cygnus look better in the UHC as well.

So getting the UHC might be a matter of taste and telescope (aperture).   But the O-III is better in most cases, in my opinion.

Robert

Sent from my iPad

On Apr 29, 2012, at 11:53 AM, Michael Hrivnak <mhrivnak at hrivnak.org> wrote:

> That's an interesting point I hadn't considered.  FWIW, when I was
> using my 8" all the time, I don't recall ever having a problem
> focusing with the O-III.  I would sometimes just pan around to find a
> bright enough star, focus on it, and then go back to the object.  And
> honestly, that's what I still do sometimes in the 18".
> 
> Michael
> 
> On Sun, Apr 29, 2012 at 11:40 AM, Alexey Toptygin <alexeyt at freeshell.org> wrote:
>> I've heard it's a lot easier to focus a UHC filter because you can see the
>> stars in H-beta (whereas in O-III they're almost completely gone).
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