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Old 20-02-2020, 03:41 AM
Grantd53
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Narrow Band Filters for visual

Hello, I am interested in buying some narrow band filters for visual use.
I am looking at either baader or astrnomik filters.

Before I purchase anything, I thought I wuold ask for some
recommendations and advice on which filters work best ...

Some questions I have are ...
Which visual filters are best ?
What can I expect to see from the different filters ?
Can visual filters also be used for astrophotography ?

Any advice and or recomendations would be appreciated ....
Regards Grant
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  #2  
Old 20-02-2020, 07:51 AM
glend (Glen)
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Well first off, some narrowband filters are well down the visual range of the human eye, Ha and Sii specifically, in the deep red band. Oiii and a few others are within the visual range. Secondly, narrowband filters, as used in imaging, have steep cutoffs, so only the particular frequency is allowed to pass. When used in imaging long capture times are required to gather the passed through signal, and the human eye lacks the ability to take time exposures, so your limited to what you can see at the moment, unless your doing EAA (Electronically Assisted Astronomy, which is a form of imaging that uses frame stacking in real time to build an image). There are some filters that are primarily light pollution filters, that block the usual wavelengths of some street lights, but as more and more councils move to be had spectrum LED lighting these filters are less effective. However, selective broader band filters can be useful for visual use in light polluted skies.
The filters you choose need careful selection for your particular area and situation. Research is key.
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Old 20-02-2020, 08:17 AM
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Outcast (Carlton)
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Quote:
Originally Posted by Grantd53 View Post
Hello, I am interested in buying some narrow band filters for visual use.
I am looking at either baader or astrnomik filters.

Before I purchase anything, I thought I wuold ask for some
recommendations and advice on which filters work best ...

Some questions I have are ...
Which visual filters are best ?
What can I expect to see from the different filters ?
Can visual filters also be used for astrophotography ?

Any advice and or recomendations would be appreciated ....
Regards Grant
I have a couple of articles/presentations on this subject but, they are too big to post on the forum. If you would like to send me a PM with your email address, I will happily email them to you. They contain relatively easy to follow explanations of the various filters available for visual work (including narrowband) & explain what they do & how they work. You may find them useful in informing your decision.

Cheers
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Old 20-02-2020, 08:40 AM
Startrek (Martin)
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I observe under Bortle 7/8 skies in suburban Sydney and Bortle 3 skies rural south coast NSW
My Astronomic UHC filters work extremely well under Bortle 3 skies observing emission nebulas , clusters and galaxies etc... but donít really help a lot under Bortle 7/8 skies
In most cases UHC and LP visual filters are only as good as your sky conditions allow and sometimes donít offer an improved view at all
The only filters I use that work in both sky conditions are my planetary and moon filters
Hopefully other visual astronomers can offer some more advice
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Old 20-02-2020, 11:18 AM
Grantd53
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Glen,
Thank you for your reply.
It has helped me understand the filter graphs a bit better.
Electronically Assisted Astronomy sounds very interesting.
Grant
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Old 20-02-2020, 11:27 AM
Grantd53
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Carlton,
Thanks for your reply.
I would like to read your articles / presentations.
I have pm'd my email address.
Grant
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Old 20-02-2020, 11:33 AM
Grantd53
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Martin,
Thanks for your reply and advice.
I live in Melbourne, so I expect I will have similar problems.
I will do some research about "Bortle ... skies". I have never heard the term before.
Grant
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Old 20-02-2020, 09:17 PM
ausastronomer (John Bambury)
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Quote:
Originally Posted by Grantd53 View Post
Hello, I am interested in buying some narrow band filters for visual use.
I am looking at either baader or astrnomik filters.

Before I purchase anything, I thought I wuold ask for some
recommendations and advice on which filters work best ...

Some questions I have are ...
Which visual filters are best ?
What can I expect to see from the different filters ?
Can visual filters also be used for astrophotography ?

Any advice and or recomendations would be appreciated ....
Regards Grant
Hi Grant,

I gave a presentation on "Visual Astronomy and the Use of Filters" at the Ice In Space Astro camp about 8 years ago.

You can download a PDF of my Presentation from here on the IIS Website

A couple of things are worth noting.

1) No filter is a substitute for clear dark skies
2) Narrowband (UHC Filters) generally are designed to work with an exit pupil of between 2mm and 4mm

The Astronomik UHC is very good. It has a fairly wide bandpass for a UHC and doesn't destroy the view of embedded clusters within nebulosity, like some other narrowband filters, but still provides a good gain on the nebulosity itself.

If I could only own one filter for visual astronomy it would be the DGM Optics NPB Filter, which is made by Omega Optical and also sold by them, as the Omega Optical NPB Filter

http://www.npbfilters.com/order-international.html

https://www.omegafilters.com/product/4384

https://www.omegafilters.com/product/4385

Of all the visual filters I own, have owned and have used used over the past 40+ years of visual observing (that's quite a few) it provides a decent gain on the largest range of targets and on the largest number of targets, compared to any other filter I have used. The added bonus is that compared to some of the other visual filters it is reasonably priced. It is a fairly tight bandpass UHC filter and it works exceptionally well.

Cheers
John B
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Old 21-02-2020, 09:04 AM
gaseous (Patrick)
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I can second what John has said, despite having a lifetime's less observing expertise than him. The DGM NPB is my most-used filter, and doesn't give the same greenish tinge to all the stars that most straight OIII filters do.
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Old 21-02-2020, 10:34 AM
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Quote:
Originally Posted by ausastronomer View Post
Hi Grant,

I gave a presentation on "Visual Astronomy and the Use of Filters" at the Ice In Space Astro camp about 8 years ago.

You can download a PDF of my Presentation from here on the IIS Website

Cheers
John B
That's one of the presentations I sent him; didn't realise it was your's John...

Cheers
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