Filters for Singapore sky

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zymon
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Filters for Singapore sky

Post by zymon »

Although the Haze is stopping me using m new telescope I was wondering what filters you all recomend for DSO in Singapore skys?
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Mariner
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Re: Filters for Singapore sky

Post by Mariner »

For astronomical filters (excluding colour filters), the common ones are broadband, narrowband and line filters. These are also split into both visual and astrophotographic uses. I shall assume at this stage you're only interested to know more about the visual ones.

Broadband filters filter off some of the skyglow caused by street lights. Examples are Lumicon Deepsky, Orion Skyglow filter and Celestron LPR filter.

Narrowband filters are more aggressive and only allow a specific set of the light spectrum through. The best examples are the Lumicon UHC, Orion Ultrablock and DGM NPB.

There are 2 examples of line filters , namely Oxygen-III and Hydrogen-Beta. These only allow specific line of the light spectrum through and are specialist filters.

Some filters work best on some DSOs and not others. Here's a good article from the Cloudy Nights' resident filter guru on the efficacy of these visual filters on DSOs:

http://www.cloudynights.com/item.php?item_id=1520

As a guide, the first filter I would recommend you to get is a narrowband filter as it is the most useful of the lot.

However, as a word of caution, do not expect them to work miracles. They can only enhance the contrast by darkening the sky background, they do not make DSOs brighter. And although they help in light polluted skies, these filters tend to work best under dark skies.

Clear skies.
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zymon
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Re: Filters for Singapore sky

Post by zymon »

Thanks a million - so much to read! but its interesting stuff!
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Mariner
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Re: Filters for Singapore sky

Post by Mariner »

I guess Astronomical filters have been overshadowed by N95 filters.

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Re: Filters for Singapore sky

Post by cloud_cover »

Yeah, but the light throughput of N95 filters really... suck.
In Singapore I've only found 1 filter that works: the UHC filter ( its a narrow band)
Get yourself a good one like those made by Lumicon or Astronomiks.
You can also buy them used from astromart or cloudynights to save a bit of cash.
Even then, you must understand that these filters only boost the contrast on emission and planetary nebulas, due to their higher emission of the H2 and O3 spectra. They are not useful on reflection nebula (such as M45) or broadband targets (namely starlight) such as galaxies and clusters. In fact a good UHC will cut down severely on visible stars.
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Re: Filters for Singapore sky

Post by Airconvent »

Under current hazy conditions, your worse friend is the sodium light from our highway lights being reflected off not only the clouds but now the dust as well and giving them that reddish glow. A broadband filter would work best to block out this unwanted part of the spectrum range. Plus broadband filters are the cheapest to buy so good to keep on in your accessories box if you are obbing frequently in Singapore.
But as cloudcover has indicated, this filter blocks out the unwanted spectrum and does not boost the targeted dim object not see through clouds, so don't treat them as cure-all for bad skies.
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ivan
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Re: Filters for Singapore sky

Post by ivan »

zymon wrote:Although the Haze is stopping me using m new telescope I was wondering what filters you all recomend for DSO in Singapore skys?
For narrowband filters, Oxygen III and H-Alpha filters would be the most useful ones, followed perhaps by H-Beta. Whether to use OIII or HA would depend on the type of emissions nebula. Alternatively, you can shoot in monochrome and colour map the images from the different filters.

If your budget is tight and you can only afford broadband filters, I would recommend either the Astronomik CLS or the Hutech IDAS LPS-V4. Once again, these work best on emissions nebulae and are unlikely to improve the contrast on other DSOs.
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Mariner
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Re: Filters for Singapore sky

Post by Mariner »

ivan wrote:
zymon wrote:Although the Haze is stopping me using m new telescope I was wondering what filters you all recomend for DSO in Singapore skys?
For narrowband filters, Oxygen III and H-Alpha filters would be the most useful ones, followed perhaps by H-Beta. Whether to use OIII or HA would depend on the type of emissions nebula. Alternatively, you can shoot in monochrome and colour map the images from the different filters.

If your budget is tight and you can only afford broadband filters, I would recommend either the Astronomik CLS or the Hutech IDAS LPS-V4. Once again, these work best on emissions nebulae and are unlikely to improve the contrast on other DSOs.

I'll have to disagree with that. H-alpha is not a filter for visual use. Not the non-solar ones anyway. Narrow band filters are those of the UHC, NPB, Ultrablock types that limit the light spectrum to that of the 2 O-II lines and H-beta. Line filters only emit either O-III spectra or H-beta.

For visual broadband, you can look into the following, just to name a few: Celestron LPR/UHC, Lumicon Deepsky, Orion Skyglow series, Astronomik CLS.

I would recommend saving your money on a narrowband filter instead as this is the more useful of the lot according to David Knisely's article.
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antares2063
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Re: Filters for Singapore sky

Post by antares2063 »

agree with Mariner...H-alpha filters aren't suited for visual, they are more suited for photography of nebulas like North american neb (Cygnus) or Horsehead (Orion) which glows in the H-alpha wavelength..ours eyes are very un-sensitive to wavelength near the red end of the spectrum..

on a side note, take note that H-alpha filters come in 2 types, one for Solar and one for night sky/DSO use..dont ever mix up the two!

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ivan
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Re: Filters for Singapore sky

Post by ivan »

Mariner wrote:
ivan wrote:
zymon wrote:Although the Haze is stopping me using m new telescope I was wondering what filters you all recomend for DSO in Singapore skys?
For narrowband filters, Oxygen III and H-Alpha filters would be the most useful ones, followed perhaps by H-Beta. Whether to use OIII or HA would depend on the type of emissions nebula. Alternatively, you can shoot in monochrome and colour map the images from the different filters.

If your budget is tight and you can only afford broadband filters, I would recommend either the Astronomik CLS or the Hutech IDAS LPS-V4. Once again, these work best on emissions nebulae and are unlikely to improve the contrast on other DSOs.

I'll have to disagree with that. H-alpha is not a filter for visual use. Not the non-solar ones anyway. Narrow band filters are those of the UHC, NPB, Ultrablock types that limit the light spectrum to that of the 2 O-II lines and H-beta. Line filters only emit either O-III spectra or H-beta.

For visual broadband, you can look into the following, just to name a few: Celestron LPR/UHC, Lumicon Deepsky, Orion Skyglow series, Astronomik CLS.

I would recommend saving your money on a narrowband filter instead as this is the more useful of the lot according to David Knisely's article.
Yes you're right. I was actually thinking of filters for AP when I was answering the question. Didn't realise OP was asking for visual purposes.
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