#1  
Old 29-05-2017, 04:09 PM
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traveller (Bo)
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light pollution filter for mono imaging

Hi all,
Just starting out in mono imaging so I want to get it right.
Just for background info, I live 10km from Melbourne CBD, so light pollution is moderate to heavy.
Based on my limited reading, I will need a light pollution filter when imaging with the luminance filter only and not with RGB filters.
Of course, imaging with NB filters will not be an issue in light polluted areas due to the narrow band pass.
Can someone please confirm this?
thanks
Bo
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  #2  
Old 30-05-2017, 08:48 AM
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rustigsmed (Russell)
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Hi Bo,

Yes most (good) RGB filters cut off where the common light pollution emission lines occur.

I can recommend the astromik ccd cls filter. there are others out there as well.

and also correct regarding nb.

Cheers,

Rusty
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Old 30-05-2017, 09:17 AM
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Atmos (Colin)
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In the city it may just be better shooting pure RGB.
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Old 30-05-2017, 09:21 AM
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I am using L-Pro filter (by Optolong bought from Cyclps Optics), it is as good as it gets (I even checked the spectral response with my spectrograph, and it is behaving like published transmission graph).
See here:
http://www.iceinspace.com.au/forum/s...ighlight=L-pro
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Old 30-05-2017, 09:56 AM
glend (Glen)
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Cyclops Optical in Hong Kong has a new multispectral filter for imaging from light polluted cities:

https://www.cyclopsoptics.com/filter...pectra-filter/

I don't know much about it, just received an email from them about its release. The web page details its spectral profile and some example photos with and without it on the same target. Just pull up the Description link to see the spectrum and photos (page down).
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Old 30-05-2017, 12:27 PM
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Bart
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Ive always been happy with my IDAS LPS P2 filter. easy colour correction, if at all.
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Old 30-05-2017, 01:37 PM
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+1 IDAS Filter
That being said, I find LRGB challenging to say the least from home (Burwood, Melbourne) which is one of the reasons I prefer NB.
I've done some LRGB imaging though, and yes only filtering the Luminance.
When I shoot RGB stars for overlaying on NB images I use no filter and limit my exposures to 60-120 secs.
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Old 30-05-2017, 01:38 PM
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Thank you all,
Russell, I have the Astronmik CLS CCD EOS clip in filter and am very impressed with its performance. I also have a Baader 2" UHC-s which I found a bit too aggressive.
Bojan and Glen, I will look up those options you mentioned.
Bart, yes, I have heard good review of the IDAS filter, but good to have verification.
Bo

Edit, thanks Andy for the exposure tip!
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Old 30-05-2017, 07:36 PM
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I use a 2" CLS CCD filter in front of all other filters on the coma corrector.
I have LRGB Ha 2" filters.
I find that it's good to just leave it there as
it also protects the inside of the filter wheel from dust.

If I was imaging outside Melbourne at a dark site I would take it off.

see here:
https://www.flickr.com/photos/247194...in/photostream
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Old 31-05-2017, 06:00 PM
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traveller (Bo)
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Thanks Al,
It's a toss up between the CLS CDD and the IDAS LPS P2 at the moment.
Bo
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Old 31-05-2017, 07:08 PM
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PRejto (Peter)
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I've used both the IDAS and CLS filters on my TEC refractors imaging from Sydney. They are both good but in heavy LP I think the CLS does a better job for luminance. With the IDAS I just put it in front of all my LRGB filters and was quite satisfied with the result. With the CLS I replaced the luminance filter and selected RGB filters that offered some help in cutting LP frequencies. When I last checked Baader seemed to feature this more than the Astronomic filters. One thing has become quite clear to me imaging from a LP site is that you cannot collect too much data; the more the better!

Peter
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Old 31-05-2017, 07:38 PM
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Quote:
Originally Posted by traveller View Post
Thanks Al,
It's a toss up between the CLS CDD and the IDAS LPS P2 at the moment.
Bo

Thanks Bo,
there's a good "mouse over picture here:
http://www.cwjames.info/astro/howto/...k_CLS-CCD.html

I used to image from a street with a whole row of sodium orange street lights.
If I just unscrewed the filter & looked down the street
it looked almost completely dark.
It's amazing as without the filter the sky noise was terrible.

You still need to take much more data than from a dark site
when using such a filter but you can get great results
from a light polluted location with nebulas.
Galaxies are however quite difficult without huge amounts of data.

cheers
Allan
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Old 31-05-2017, 08:22 PM
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traveller (Bo)
Not enough time and money

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Thank you Peter and Allan,
I have an Astronomik CLS CCD EOS clip in filter, which I am very happy with.
Totally agree with data, esp for galaxies as Allan said.
That or hope my lotto hits the jackpot and I can get a bush block.
Bo
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