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PeterCPC

New LED street lights and filters

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We recently had the new LED type street lights installed and it has had an adverse effect on light pollution. I generally use a modded 1200d with a CLS clip filter and this was good for the sodium lights but now my shots seem more affected by light gradients than before.

Has anyone come across a way to reduce the effect of these new LED lights?

Would a Baader Neodymium filter in addition to or instead of the CLS do any good? I am wary of spending over £100 on a filter if it is not going to improve matters markedly.

Any suggestions would be welcomed.

Thanks.

Peter

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I think the best solution for everyone is the Local authorities fitted cloud sensors to streetlamps, cloudy Street lights on --clear skies Street lights off.

Seriously I really do not know the answer but always read these posts just in case the solution is available.

Sorry I am not much help.

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LED's emit light all across the spectrum. This explains why people engaged in astronomy, and other activities that rely on dark skies, are encouraged to approach their town-city councils before they install these things. They can be fitted with directional masks to keep their light from lighting up the whole sky. Doing this before they are up is less money than a retro-fit.

As they emit their brilliance across the whole spectrum, filters are virtually useless. Except perhaps this:

http://www.telescope.com/Astrophotography/Astrophotography-Filters/Orion-125-Dark-Frame-Imaging-Filter/pc/-1/c/4/sc/63/p/113382.uts

Sorry - couldn't resist.....

Dave

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Yes.... thanks for that Dave. Actually, I asked for and got masks retro-fitted on two nearby lights but it doesn't seem to make much difference.

Peter

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As there are no further responses I assume that this is a wild goose chase. In short, LED lights are like clouds - sent to try us.

Peter

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Hopefully they at least go off at 1am in Summer and 12 am in winter though means less sleep!

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I know have quite a few expensive LP filters (including a 77mm IDAS) that do little or nothing to handle the LED light  related sky gradients... :cry::(

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Peter, I used to work for an LED producer and the light emitted is pretty much as is, the only benefit is the light is directional as stated above and is normally shrouded at the top and faces downward. The warm white is the best colour for astro but unfortunately most are white light. The effect I am afraid renders all current filters useless.

I am in discussions with my local council to fit a shroud as there is a new LED light directly outside my house, it is proving to be quite a challenge for reasons unbeknown to me. It doesn't affect my observing but the bright LED stops me going back to sleep should I wake up in the early hours.

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Peter, I used to work for an LED producer and the light emitted is pretty much as is, the only benefit is the light is directional as stated above and is normally shrouded at the top and faces downward. The warm white is the best colour for astro but unfortunately most are white light. The effect I am afraid renders all current filters useless.

I am in discussions with my local council to fit a shroud as there is a new LED light directly outside my house, it is proving to be quite a challenge for reasons unbeknown to me. It doesn't affect my observing but the bright LED stops me going back to sleep should I wake up in the early hours.

That means you could be tired during the day with all sorts of other possible consequences. Health and safety springs to mind. I wonder how they'd react if you mentioned this, particularly if it was on a solicitor's letter head. Just a thought :)

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Richard,

I was hoping not to go down this route due to the hidden costs involved on the tax payer. I have just involved the local councillor and hopefully this will be enough, after all it is only a shroud that is needed. But you are right about tiredness etc.... and if I have to I will tread this path.

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Yes it was a bit tongue in cheek, but you have a very strong case for a shroud, there is plenty of evidence to show that bright light affects our bio rythems. Even if they can't do it straight away they could at least acknowldge they'll get around to it eventually but I got the impression they were being difficult. It's none of my business of course and I should have realised you would have thought of this. I hope it doesn't take too long to resolve. :)

Edited by Scooot

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Thanks Stuart...

I have Spent the last 25 years working In Optoelectronics R&D mainly in the Medical and Industrial uses of Lasers and intense pulsed light using custom multiband di-electric filters and the last 8 years working with LED's including custom multi chip packages...

I would like to think that I know what can and can' t be achieved... Which is why I'm so  glum :(

Peter...

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Thanks to all for your input. I would say that you should not get your hopes up about shrouds on these lights. The Council have fitted 2 on nearby lights and it makes no difference at all.

Oh well, I have saved money on a Baader Neodymium I suppose.

Peter

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I keep saying this but once more  won't hurt...  The lights around me are very directional but stupidly bright from a visual observing point of view they are an "improvement"

My problem at least for long exposure  imaging isn't direct illumination but rather the back scatter of the ground etc... Which is especially bad when the grounds light coloured, wet, frosty or  (and I am going to dread this one) covered in a layer of snow...

Peter...

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I did have some success with the involvement of local councillors. Here is my story. I am still affected though, and tend to stick to narrowband.

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I've looked at a few of the LEDs around with my portable spectroscope and notice that the spectrum is not truly continuous and smooth: there is a darker band in the emission spectrum between the bright blue emission band and green. I suspect that this would enable some increase in contrast to be obtained in an image if a broadband filter were used centred on this "darker" band?

350px-White_LED.png

This is the classic pattern:- Filtering at 500nm will reduce a lot of the emission, particularly the bright blue part which scatters more of course from haze and water droplets in the air.

Chris

Edited by chiltonstar

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