LED street lighting

[brajeng]

Good morning, Our local council has set up a plan to change all street lights from the old Sodium vapour to LED. Sounds good, but it raises a query. Is the light from these lights as White as they look?? I've become used to using an Hutec IDAS filter for all work, will I need it any more???

On first sight the lights look very good indeed, directing their light only downwards, with very little out to the side ot upwards.

[Alien 13]

The impact of these lights can vary for me as an imager the sky is much darker but the line of sight intensity of a particular light would be bad news for an observer.

LP filters might still be useful if there is any distant orange sky glow but would have no effect on the white light.

Alan

[michael.h.f.wilkinson]

Sodium light (in particular low-pressure types) emit just a few spectral lines, which are readily blocked by LPR filters. Unfortunately, the continuum emission from LED lights cannot be blocked without reducing starlight by the same amount. If the new lights are well shielded, as you suggest, the net effect may actually be positive.

[PeterCPC]

My experience is that the new LED lights are just as, if not more, troublesome as the sodium lights. The white light does "escape" and is not all directed downwards. Even putting shields on two lights near to me has had very little effect.

Peter

[Starlight 1]

Astro lounge post.

[spaceboy]

LED lights are no good at all unless your local council plans to dim or switch them off at night. They are like football stadium lighting if your garden is anywhere near the vicinity of one. The light is so blindingly white on them if you catch even the slightest glimpse of one you can kiss your night vision good night. As others have also commented there is no filtering out the LED lights either. What I will say though is if you happen to be well off and live out in the sticks you will see an improvement as I do admit the skies directly above seem to benefit from the orange glow of the horizon receding some. But then again if your an astronomer who lives in the sticks you got it made anyway.

[ronin]

The light is white, how "much" white is dependant on what is fitted. One set I drive past/through is actually not very intense and is best described as a pale or weak white - difficult to explain.

Another bit of the problem is we talk of "light pollution" that is generally light going where not wanted, usually a yellow/orange glow over a town when seen from some distance away. These new lights direct the light down more and there is less direct loss upwards, so less "light pollution" - it is going where intended. Makes a difference if you re observing from say 5 miles away and looking over the town, but I would say not greatly relevant if you are in the town. You are in the pool of light.

A white light will just about destroy any chance of getting decent night vision, the rods (think it is the rods) in the eye just will not come into play as the wavelengths other then some of the red will suppress them.

May be a good time to ask about shielding, they may shield as they install, and if you or someone is there it allows the chance to ask/remind the installation people about a shield. Be pleasant or the unit might just end up directed a bit more towards you - it is amazing how a pleasant request can get you further then just about all other options.

[beamer3.6m]

Will red glasses shield the light.

Not practical but just wondering if the lights had a red coating if this would be better.

[Adamar98]

We had them fitted down my street a few months ago. I think they're much better than the old sodium ones. Most of the light is directed down. I now have a fairly dark sky above me and not a horrid glow of orange.

[DaveS]

LEDs *can* be better but they have to be designed and installed correctly. The one over the road from me is pretty dire though not that bright, but the ones on a main road I use quite often are very well directed, in fact nearly invisible beyond the direct light pool. I think councils look at the efficiency / cheapness of LEDs and use it as an excuse to increase the brightness over what the old sodium lights provided, pandering to the night-phobia of the sheeple.

I fear we may have to move to narrow-band imaging and chose our targets carefully, as though imaging in moonlight.

[chiltonstar]

Looking at the spectrum of local LED streetlights with my portable spectroscope, there is a bit of a gap between the blue band and the rest of the emission. I think you may get some improvement in contrast therefore if you use a filter centred on the "gap"  (ie at about 490 - 500nm). This will also have the effect of removing a lot of the blue emission which is mainly responsible for scatter, eg from haze.

Chris (originally a spectroscopist )

[beamer3.6m]

Looking at the spectrum of local LED streetlights with my portable spectroscope, there is a bit of a gap between the blue band and the rest of the emission. I think you may get some improvement in contrast therefore if you use a filter centred on the "gap" (ie at about 490 - 500nm). This will also have the effect of removing a lot of the blue emission which is mainly responsible for scatter, eg from haze.

Chris (originally a spectroscopist )

Can you recommend a filter?

[CSM]

See http://www.britastro.org/dark-skies/cfds_issues.php?topic=bluerich

[chiltonstar]

Can you recommend a filter?

If you have a Lumicon UHC, it might be worth trying as this has a blue/green bandpass in the right place. It lets through some red though, so you might need to filter this out with a pale blue filter added as well. Worth trying.

Chris

[Charic]

.......I just hope they don't  reach  my street!

Their installing them in the town centre and approach roads, and boy are they bright, blinding if you care to look at them!

They have to be bright, see how much taller they are?

[Jambonature]

Hi, I've just been in touch with the local council to address some LED streetlights Infront and behind the house. Recommended some sort of shielding to decrease wasted light, increase effeciency etc

I'll let you know how it goes. Since the light wavelength for LED is not very long the sheild should be enough hopefully. Seems to be a common problem the more you look into it however doesn't feel like they will stop. Only a matter of time before thier everywhere i feel as the concern for excess light has been addressed with a few options. Council will either black out selected LEDs with paint, Add a Light Sheild or Dim the lights at selected hours by having full control on each area. Could have just made them shorter with less power which then equals to more savings.

Anyway In our case the garden is in direct path of a street light which was added after a recent housing development behind the property. A simple straw fence behind my garage would have been a quick solution for the garden however i'm sure others living their would benefit from the less light so only felt right to send them a quick message. Let see how it goes..

added a link to the site i used, Hope it helps

Report it online - Hounslow Highways

[spaceman_spiff]

I think that although the light is broadband (i.e. harder to filter out) the LED lights tend to be better shielded which more than makes up for their colour. I posted a topic on this a while ago.

http://stargazerslounge.com/topic/247896-led-streetlights-not-as-bad-as-i-thought/

Happy holidays!!! 

[rubecula]

We've had them for about a year now.  They do direct the light downward but they are on much taller poles so that they can get a better spread of light.  Ours are a good 1.5 metres taller.  I did contact the council and they sent someone round to look at them.  They said that that the design didn't allow them to fix a shield.  However they did agree to dim them, but this doesn't happen until midnight.