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Old 15-11-2014, 10:21 PM
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Camelopardalis (Dunk)
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Question Light pollution filter for DSLR imaging...

Folks,

I'm looking for a light pollution filter to use at home, but our local streetlights are the white type (LED?).

Would the IDAS LPS-D1 be effective for this kind of light? I'm interested in nebulae, and galaxies if it'd work with that too.

Any thoughts, suggestions?

Thanks,
Dunk
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Old 16-11-2014, 12:18 PM
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kosh (Goran)
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Hi Dunk,

Not sure if this will answer you question but i posted a couple of comparison photos earlier in the year using my Astronomik CLS-CCD LP filter. I have a mixture of orange and white streetlights and it seems to do quite well. Check out about half way dow the thread for the shots. (single frames ).

http://www.iceinspace.com.au/forum/s...d.php?t=118924

Goran.
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Old 16-11-2014, 02:07 PM
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Thanks Goran, that's really helpful...looks like a BIG difference there love the shots btw!
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Old 17-11-2014, 06:02 AM
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ZeroID (Brent)
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Hi Goran,
Your local white lights, are they LED or incandescent ?
I've been reading up a bit on LED lights and one of the problems astronomically is that they are a much wider spectrum and therefore a lot harder to filter out. Sodium or mercury lights have distinctive peaks in their output which can be selectively filtered whereas LEDs not so easily. Their advantage is they are normally more efficient with how they are directed and the usual save power factors.
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Old 19-11-2014, 07:04 PM
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Quote:
Originally Posted by Camelopardalis View Post
Thanks Goran, that's really helpful...looks like a BIG difference there love the shots btw!
Thanks! Unfortunately not alot of activity lately though.

Quote:
Originally Posted by ZeroID View Post
Hi Goran,
Your local white lights, are they LED or incandescent ?
I've been reading up a bit on LED lights and one of the problems astronomically is that they are a much wider spectrum and therefore a lot harder to filter out. Sodium or mercury lights have distinctive peaks in their output which can be selectively filtered whereas LEDs not so easily. Their advantage is they are normally more efficient with how they are directed and the usual save power factors.
I think they are incandescent. I had no idea that they even used led for streetlights.
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Old 19-11-2014, 07:13 PM
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ZeroID (Brent)
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Currently our local streetlights are predominantly Sodium (Yellow cast) and the Astronomik CLS CCD filter seems to work although it lengthens exposure time quite a bit. I haven't got anything else to compare it with although I have been experimenting with a standard Wratten C80A (Light Blue) filter. It seems to be effective and not too hard to counterbalance the bluish cast in processing. Again it requires longer exposure times.
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Old 19-11-2014, 11:03 PM
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I could be wrong my local lights might be normal ones, but they're definitely white and they're fairly directional...doesn't mean they're LED I suppose, but with all of Sydney's light pollution I'm not sure it'd make much difference

I know LEDs are quite popular for their energy efficiency in some places.
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Old 20-11-2014, 12:24 AM
glend (Glen)
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Dunk save your money and use it for fuel to Bretti or Wirunna. Trying to get good images in the city is just too frustrating. A couple of nights a month at a dark sight will get you lots of subs to play with when you get home.
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Old 20-11-2014, 06:33 AM
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Quote:
Originally Posted by Camelopardalis View Post
I could be wrong my local lights might be normal ones, but they're definitely white and they're fairly directional...doesn't mean they're LED I suppose, but with all of Sydney's light pollution I'm not sure it'd make much difference

I know LEDs are quite popular for their energy efficiency in some places.
Mercury Blue\White ?
Incandescent (filament) are actually quite yellow\red in their output and these days pretty rare for street lights unless it's for retro look stuff.
CLS manages the Mercury spectrum according to the specs.
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Old 20-11-2014, 08:29 AM
julianh72 (Julian)
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Quote:
Originally Posted by Camelopardalis View Post
I could be wrong my local lights might be normal ones, but they're definitely white and they're fairly directional...doesn't mean they're LED I suppose, but with all of Sydney's light pollution I'm not sure it'd make much difference

I know LEDs are quite popular for their energy efficiency in some places.
Road lights and industrial floodlights etc (which are the main source of general light pollution) are still pretty well all sodium or mercury these days, but you do see other technologies in areas where lower illumination levels are acceptable (parks, cycle paths, etc), including fluorescent tubes, CFLs , LEDs , etc.

High-pressure sodium lights give a yellowish white light, while high pressure mercury lights look white at first sight, but actually have a strong green cast. Because both are emission sources, they have a narrow band emission spectrum, so are responsive to light pollution filters.

LEDs are starting to be used in industrial lighting applications. They cost quite a bit more than the mercury and sodium lights that they replace, but have much longer lifetime between replacement, and much lower energy costs, so are cheaper over their lifetime, despite their higher installation cost. They are also designed to point much more accurately than the older light fittings, so can generate a lot less light spill / pollution. I would expect to see them make their way into public spaces over the coming years, but it will probably be a couple of decades before the transition is complete, because they are still not a viable option for the high-mast lights that you see at major intersections, sports stadiums, etc.
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Old 20-11-2014, 09:56 AM
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Quote:
Originally Posted by ZeroID View Post
Mercury Blue\White ?
Incandescent (filament) are actually quite yellow\red in their output and these days pretty rare for street lights unless it's for retro look stuff.
CLS manages the Mercury spectrum according to the specs.
Thanks Brent - so there is hope definitely on the blue/white side, not yellow/red.
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Old 20-11-2014, 09:57 AM
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Originally Posted by glend View Post
Dunk save your money and use it for fuel to Bretti or Wirunna. Trying to get good images in the city is just too frustrating. A couple of nights a month at a dark sight will get you lots of subs to play with when you get home.
Yeah I hear you glen and I definitely will when I can, but some nights even in the City look just too good to waste. And it's not like I don't need to refine my techniques
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Old 20-11-2014, 10:00 AM
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LEDs are starting to be used in industrial lighting applications. They cost quite a bit more than the mercury and sodium lights that they replace, but have much longer lifetime between replacement, and much lower energy costs, so are cheaper over their lifetime, despite their higher installation cost. They are also designed to point much more accurately than the older light fittings, so can generate a lot less light spill / pollution. I would expect to see them make their way into public spaces over the coming years, but it will probably be a couple of decades before the transition is complete, because they are still not a viable option for the high-mast lights that you see at major intersections, sports stadiums, etc.
Thanks Julian - makes me believe more that they're mercury here, although they're well shielded because they cast mostly down, at least, in my neighbourhood

Where I'm from originally, LED streetlights are commonplace...yes they cost more to install but they use a fraction of the energy and have much lower maintenance costs. Or at least, that's what the local councils told central government when they were suckling for subsidies but some councils are even more faithful to the spirit of saving energy and actually switch the things off late at night! No "coal is our future!" there
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Old 24-11-2014, 11:25 AM
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...but some councils are even more faithful to the spirit of saving energy and actually switch the things off late at night!
They do this in some parts of England also a friend tells me. Wish they did that here!
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Old 24-11-2014, 02:02 PM
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They do this in some parts of England also a friend tells me. Wish they did that here!
The street lights here were blacked out a couple of nights ago. It made no difference since there's so much LP from the rest of Sydney.
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Old 30-11-2014, 01:33 AM
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I use an Astronomik CLS clip in filter. Its nice and dark where I live but when I go to my brother's house in Houston the light pollution is terrible. The CLS works well to kill the light pollution. It will impart a green cast to your images however. Easily taken care of with a free filter called HLVG Hasta La Vista Green. You should also pick up WhiteCal and the other color manipulation filter they have on the site. I use HLVG and WhiteCal but haven't messed with the other one. I really like the clip in filters. I have a large variation in my lens front elements so I would spend a lot of money if I had to equip them all or go to step down rings which I don't like to use. I had their full set of filters on my old rig and the Ha Hb and OIII. That was 15 years ago lots of new filters on the market. I've had good results from their stuff so I didn't really investigate some of the newer entries to the field.

Griz
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Old 30-11-2014, 12:49 PM
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Thanks chaps - overall I'm on the fence about whether or not I should invest. I do like the tranquility of a good dark site, and my skyline is limited at home, although north and east are OK, and overhead of course
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