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Date: 31 May 2007 17:07:20
From: brucegooglegroups
Subject: filter suggestions
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( my apologies if this was posted twice- my first message didn't
appear in the group)
Suggestions for a filter for a 4.5 Dob? I want to view Messier
objects- and in general more deep sky objects.
Bruce
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Date: 02 Jun 2007 13:01:04
From: David Knisely
Subject: Re: filter suggestions
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Bruce wrote:
> ( my apologies if this was posted twice- my first message didn't
> appear in the group)
>
> Suggestions for a filter for a 4.5 Dob? I want to view Messier
> objects- and in general more deep sky objects.
>
> Bruce
For diffuse emission and planetary nebulae, I might suggest the DGM
Optics NPB filter. It will help, even under a fairly dark sky, although
the power will need to be rather low (between 16x and 40x) for the best
results in your scope. These filters work best with an observer who is
fully dark-adapted (at least 20 minutes in total darkness) and uses
averted vision, as the enhancement of the detail is strongest for the
fainter outer features. However, these narrow-band "nebula" filters
don't help much for star clusters or galaxies, so for that, you need
mainly darker skies and some aperture. If you have a mild amount of
local skyglow, a broadband "LPR" filter can help slightly (I recommend
the Lumicon Deep-sky filter for that), but don't expect a huge
improvement in the view. Clear skies to you.
--
David W. Knisely KA0CZC@navix.net
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/
**********************************************
* Attend the 14th Annual NEBRASKA STAR PARTY *
* July 15th-20th, 2007, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************
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Date: 03 Jun 2007 00:01:13
From: brucegooglegroups
Subject: Re: filter suggestions
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On Jun 2, 2:01 pm, David Knisely <KA0...@navix.net > wrote:
> Bruce wrote:
> > ( my apologies if this was posted twice- my first message didn't
> > appear in the group)
>
> > Suggestions for a filter for a 4.5 Dob? I want to view Messier
> > objects- and in general more deep sky objects.
>
> > Bruce
>
> For diffuse emission and planetary nebulae, I might suggest the DGM
> Optics NPB filter. It will help, even under a fairly dark sky, although
> the power will need to be rather low (between 16x and 40x) for the best
> results in your scope. These filters work best with an observer who is
> fully dark-adapted (at least 20 minutes in total darkness) and uses
> averted vision, as the enhancement of the detail is strongest for the
> fainter outer features. However, these narrow-band "nebula" filters
> don't help much for star clusters or galaxies, so for that, you need
> mainly darker skies and some aperture. If you have a mild amount of
> local skyglow, a broadband "LPR" filter can help slightly (I recommend
> the Lumicon Deep-sky filter for that), but don't expect a huge
> improvement in the view. Clear skies to you.
> --
> David W. Knisely KA0...@navix.net
> Prairie Astronomy Club:http://www.prairieastronomyclub.org
> Hyde Memorial Observatory:http://www.hydeobservatory.info/
>
> **********************************************
> * Attend the 14th Annual NEBRASKA STAR PARTY *
> * July 15th-20th, 2007, Merritt Reservoir *
> * http://www.NebraskaStarParty.org *
> **********************************************
Hi David,
At this point I am mostly focusing on clusters and galaxies. I also
want to locate the Dumbell nebula, and seems like a easier object to
find, so I suppose I wouldn't need a filter to find it.
You responded to a post of mine about buying a Nexstar SE8. I wanted
more experience finding deeper sky objects, and then I will venture
into buying a bigger aperture- probably the NexstarSE8.
I have been doing astronomy for a year, and I became familiar with the
constellations, using my binoculars most of the time. But it seems I
could still be able to view deep sky objects with the 4.5.
Clear Skies.
Bruce
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Date: 02 Jun 2007 08:54:33
From: brucegooglegroups
Subject: Re: filter suggestions
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On Jun 2, 4:37 am, Clipper the Horse <nostal...@mchsi.com > wrote:
> brucegooglegroups wrote:
> > On Jun 1, 1:21 am, David Nakamoto <david.nakam...@verizon.net> wrote:
> > > brucegooglegroups wrote:
> > > > ( my apologies if this was posted twice- my first message didn't
> > > > appear in the group)
>
> > > > Suggestions for a filter for a 4.5 Dob? I want to view Messier
> > > > objects- and in general more deep sky objects.
>
> > > > Bruce
>
> > > You should try out filters, hopefully at your local astronomy club's
> > > dark sky party night. If you can't, then it's harder to suggest what to
> > > get. Filters vary, and what works for one person doesn't necessarily
> > > work for another.
>
> > > And as another poster wrote, the best filter is a real dark sky. Invest
> > > in traveling every now and again, from one to a few hours, to get to
> > > such a sight. Filters in any case only partially compensate for light
> > > polluted skies, and they don't make objects brighter, they drop the
> > > background light level so there's more contrast.
>
> > > --- Dave
>
> > Thanks all for the replies. I live in a semi-rural area away from the
> > city and I live near a lot of woods and conservation land. So my skies
> > are relatively dark compared to the suburbs. There is light from the
> > neighbors, but I try to go out late enough so most of the fronts
> > lights are out and the only light is from the street lights which are
> > dimmer than the average street light. So it looks like I'll rely on
> > the dark sky as the best filter. My back yard is dark, but is only
> > good for some views, due to the trees.
>
> > I also started reading Gary Seronik's "Binocular Highlights" which
> > include many deep sky objects- and no filter is involved. So I will
> > view the objects in his book, and see how I make out without a filter.
>
> > Bruce
>
> In your situation optimising the scope for contrast will do more
> than a filter.
Hi Clipper,
By optimising- do you mean viewing in optimal condition?
Bruce
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Date: 02 Jun 2007 03:37:07
From: Clipper the Horse
Subject: Re: filter suggestions
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brucegooglegroups wrote:
> On Jun 1, 1:21 am, David Nakamoto <david.nakam...@verizon.net> wrote:
> > brucegooglegroups wrote:
> > > ( my apologies if this was posted twice- my first message didn't
> > > appear in the group)
> >
> > > Suggestions for a filter for a 4.5 Dob? I want to view Messier
> > > objects- and in general more deep sky objects.
> >
> > > Bruce
> >
> > You should try out filters, hopefully at your local astronomy club's
> > dark sky party night. If you can't, then it's harder to suggest what to
> > get. Filters vary, and what works for one person doesn't necessarily
> > work for another.
> >
> > And as another poster wrote, the best filter is a real dark sky. Invest
> > in traveling every now and again, from one to a few hours, to get to
> > such a sight. Filters in any case only partially compensate for light
> > polluted skies, and they don't make objects brighter, they drop the
> > background light level so there's more contrast.
> >
> > --- Dave
>
> Thanks all for the replies. I live in a semi-rural area away from the
> city and I live near a lot of woods and conservation land. So my skies
> are relatively dark compared to the suburbs. There is light from the
> neighbors, but I try to go out late enough so most of the fronts
> lights are out and the only light is from the street lights which are
> dimmer than the average street light. So it looks like I'll rely on
> the dark sky as the best filter. My back yard is dark, but is only
> good for some views, due to the trees.
>
> I also started reading Gary Seronik's "Binocular Highlights" which
> include many deep sky objects- and no filter is involved. So I will
> view the objects in his book, and see how I make out without a filter.
>
> Bruce
In your situation optimising the scope for contrast will do more
than a filter.
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Date: 02 Jun 2007 02:07:40
From: brucegooglegroups
Subject: Re: filter suggestions
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On Jun 1, 1:21 am, David Nakamoto <david.nakam...@verizon.net > wrote:
> brucegooglegroups wrote:
> > ( my apologies if this was posted twice- my first message didn't
> > appear in the group)
>
> > Suggestions for a filter for a 4.5 Dob? I want to view Messier
> > objects- and in general more deep sky objects.
>
> > Bruce
>
> You should try out filters, hopefully at your local astronomy club's
> dark sky party night. If you can't, then it's harder to suggest what to
> get. Filters vary, and what works for one person doesn't necessarily
> work for another.
>
> And as another poster wrote, the best filter is a real dark sky. Invest
> in traveling every now and again, from one to a few hours, to get to
> such a sight. Filters in any case only partially compensate for light
> polluted skies, and they don't make objects brighter, they drop the
> background light level so there's more contrast.
>
> --- Dave
Thanks all for the replies. I live in a semi-rural area away from the
city and I live near a lot of woods and conservation land. So my skies
are relatively dark compared to the suburbs. There is light from the
neighbors, but I try to go out late enough so most of the fronts
lights are out and the only light is from the street lights which are
dimmer than the average street light. So it looks like I'll rely on
the dark sky as the best filter. My back yard is dark, but is only
good for some views, due to the trees.
I also started reading Gary Seronik's "Binocular Highlights" which
include many deep sky objects- and no filter is involved. So I will
view the objects in his book, and see how I make out without a filter.
Bruce
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Date: 01 Jun 2007 05:21:03
From: David Nakamoto
Subject: Re: filter suggestions
|
brucegooglegroups wrote:
> ( my apologies if this was posted twice- my first message didn't
> appear in the group)
>
> Suggestions for a filter for a 4.5 Dob? I want to view Messier
> objects- and in general more deep sky objects.
>
> Bruce
>
You should try out filters, hopefully at your local astronomy club's
dark sky party night. If you can't, then it's harder to suggest what to
get. Filters vary, and what works for one person doesn't necessarily
work for another.
And as another poster wrote, the best filter is a real dark sky. Invest
in traveling every now and again, from one to a few hours, to get to
such a sight. Filters in any case only partially compensate for light
polluted skies, and they don't make objects brighter, they drop the
background light level so there's more contrast.
--- Dave
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Date: 31 May 2007 20:52:37
From: Dennis Woos
Subject: Re: filter suggestions
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> Suggestions for a filter for a 4.5 Dob? I want to view Messier
> objects- and in general more deep sky objects.
>
A Lumicon UHC or similar narrow band pass filter is a great accessory, and
really lights up nebulae. 1.25" versions sell for around $100, though I
just got my son one on Astromart for $57. However, filter use is a matter
of taste, and you should try some out at a star party if you haven't already
done so.
Dennis
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Date: 31 May 2007 17:28:20
From: Martin R. Howell
Subject: Re: filter suggestions
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On 31 May 2007 17:07:20 -0700, brucegooglegroups wrote:
> Suggestions for a filter for a 4.5 Dob? I want to view Messier
> objects- and in general more deep sky objects.
Hi,
You didn't say anything about the sky's conditions from where you are
viewing. I would offer this: The best filter you can get is the darkest
sky you can find. If you don't have it, then seek out magnitude 6 and
darker skies if possible. Also, don't be shy about cranking up the power
on a faint fuzzy, be it Messier or otherwise, once you have located it in a
lower power eyepiece. Contrary to the opinion held by many, a shorter
focal length eyepiece can bring out features in a faint fuzzy.
One of my telescopes is a 114mm dobsonian and the only filter in my
possession for it and my 12.5 inch dobsonian is a "moon filter" (for
dimming a bright moon and also, I have found, for improving views of the
surface markings of Mars).
--
Martin R. Howell
Worldwide Amateur Astronomers
Moderated sci.astro.amateur
www.theastropost.com/moderated_sci.astro.amateur
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