Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_30_second_exp_2_winners.thumb.jpg.b5430b40547c40d344fd4493776ab99f.jpg

laser_jock99

LED Street Lights Are Bad For Astronomy

Recommended Posts

My first observation is that the floodlights haven't had any thought put into them. Many of them facing out almost horizontal . The car par area is particularly dazzling. 

A number of them seem to have failing drivers as they constantly cycle on/off.

Much of the external lighting was 28w 2D bulkhead fittings which were retrofitted with LED trays. No shielding!D3SWP_MAIN.jpg

The indoor IP56 twin fluorescent fittings were retrofitted with LED tubes and drivers. Perhaps the decision to retrofit was a bad one. Failure rates are high.

It's poor lighting design at it's best, or do I mean worst?

That sounds like a rushed job without much thought going into it. Retrofit trays / bulbs tend to have more issues as the fixture itself wasn't designed with LED in mind (and so heat dissipation, in particular, can be poor). But even taking that into account it sounds like someone's botched it and scarpered.

Share this post


Link to post
Share on other sites

Just recently had led streetlights installed well shielded and directed...i can now see stars...so yep leds gets my vote.

Share this post


Link to post
Share on other sites

I think we need to distinguish between the 'local effects' of LED installations and the overall effect of a complete 'city refit'.

Clearly if your Omni direction local sodium lamps are replaced the initial impression will be favourable. Citywide the impact is less beneficial perhaps?

Another consideration is the low cost of running the new LED lighting. At much lower cost there is always going to the temptation to install brighter lights and more of them......

Share this post


Link to post
Share on other sites

Another consideration is the low cost of running the new LED lighting. At much lower cost there is always going to the temptation to install brighter lights and more of them......

I'm not convinced to be honest, the drive gear on them puts out a huge amount of heat on the units I've had dealings with. There may be a little less energy used but overall like for like for lighting levels I don't think there is much in it.

I know sodium lamps are hot too but not much difference in relative terms

Edited by mapstar

Share this post


Link to post
Share on other sites

Looking at the big picture - the problem is not with LEDs. LEDs are good. They are cheap, they save energy, they allow for many things we couldn't do before ( dimming etc. ). It's poorly designed lamps and their overuse that's the problem. We don't need so many. We don't need them to be that bright. We don't need them to be constantly on even though there's nobody around. A simple motion sensor costs a fraction of what a street lamp does...

Forward thinking - think we're missing that.

  • Like 2

Share this post


Link to post
Share on other sites

No matter how much we complain, the fact is LED street lighting is here to stay, and will replace all the older type of lighting in due course.  With local authorities having budgets cut, the drive for more efficient forms of lighting, and as some have mentioned, more control over the lights by dimming (and thus saving more money) the days of sodium lighting was limited.

Yes it does make all those LP filters redundant, but as others have said, the skies do appear darker and unlike when sodium lights were used, the naked eye observer can see the miky way from town centres.  I agree with some of the comments about design, in that some are less shielded and still spred the light out rather than down, but then I'm sure those can be addressed directly and are not as common as it used to be.

I know we all complain about LP, but I often wonder how things were before they introduced smokless fuels and zones... you can't filter out particulate matter in the air and I bet observing from urban area's back in 50's - 60' was almost impossible !

Share this post


Link to post
Share on other sites

Well, I remember a time between the clean air act and the mad obsession with turning night into day when I could just see the Milky Way from my back garden in Acton, about half way out from the centre of London. I think the last time I glimpsed it was in the mid '80s.

Regarding LEDs, the one over the road from me spills quite a lot of light as it appears to be totally un-shielded, while the ones that a neighbouring borough installed in and around a friend's street are very well shielded, the LEDs themselves almost invisible more than a couple of street lights away. 

Share this post


Link to post
Share on other sites

I went on holiday to mid Wales in April, and right outside the cottage was LED street lights. I have to say, I was really impressed with them. It was a very rural location, so no big towns etc nearby, but there were a few A-roads that you could see in the distance, but the sky was just spectacular. Way better than I have in my (also rural) location at home, where I have to contend with the traditional sodium streetlights. I don't know anything about the type of lights they were, and they were very bright, but the light was directed down. 

I took some wide field images (with DSLR on a SkyTracker) whilst I was there. No filters were used, nor have these images been processed (they are the original jpegs taken) and images and details can be seen below: 

IMG_1705 60s exp, f5.6, ISO 800
IMG_1711 60s exp, f5.6, ISO 800

IMG_1783 147s exp, f4.5, ISO 800

Compared to similar exposure times taken at home, it is a world of difference. 
 

I understand that things may be different when taking pics using a telescope, but I have to say, I was impressed with the lighting.  I can appreciate though, that this was a very rural location - and views of the night sky may be worse when viewing from a town or city with LED lighting. 

post-24939-0-43586800-1444337732_thumb.j

post-24939-0-32400600-1444338060_thumb.j

post-24939-0-32638800-1444338126_thumb.j

  • Like 4

Share this post


Link to post
Share on other sites

Since the sodium lights around me were replaced with LEDs, the milkyway can be seen from my garden on almost every clear night with ease. I prefer them over the sodium alternative every time, though I'd prefer no lights at all if I had my way.

Mike

  • Like 2

Share this post


Link to post
Share on other sites

The LED lamps in Plymouth are waaay too bright. When I stood at the furthest point away from them in my ront garden they still glared in my eyes... Making it difficult to see the ISS. I went into my back garden and I can see what little of the milky way is at the zenith and many more stars.

LED lamps really do turn night in the streets into day. At wembury beach, though, the MW is easily visible at all altitudes. I think Plymouth would be an excellent place for astronomy if those LED lamps were half or 1/3 the brightness.

I saw around mag 5.2 at wembury, although that was a struggle and close to the best part of the sky.

  • Like 1

Share this post


Link to post
Share on other sites

A simple motion sensor costs a fraction of what a street lamp does.

But doesn't the benefit (to astronomers) of a motion-sensor rather depend on the area over which the sensor operates? It seems to me that, for a streetlight to be of any use to drivers, that the distance involved is going to have to be quite large, or the car would be past before the light turned on. And, with no fewer than seven streetlights needed to keep my front garden "safe" (based on the number the council have installed that spill light directly onto it) isn't me moving around with my telescope likely to set off at least one of them?

Not trying to be argumentative ... I genuinely do not know.

Share this post


Link to post
Share on other sites

Visually (at least when the grounds dry) they are better you can even see stars fairly low to the horizon over the top of the lamps and the MW is visible overhead, the gardens pretty dark away from the bright pools of light (which don't help with preserving dark adaption) .. The house is a lot darker inside which has taken a bit of getting used to - especially for those midnight trips to the neccessarium...

The problem is when I'm imaging gradients appear in even relatively short exposures and you can't do anything about them....

Peter...

Share this post


Link to post
Share on other sites

 It seems to me that, for a streetlight to be of any use to drivers, that the distance involved is going to have to be quite large, or the car would be past before the light turned on. .

Don't cars have headlights? Streetlights are for pedestrians.

Share this post


Link to post
Share on other sites

I was attempting to build on some of the posts above:
#19 "when driving humans ideally need ... "
#25 "Driving through the lanes fitted with them ..."

But whether for cars or pedestrians, the distance at which the sensor operates would surely still be important. If it operates for pedestrians walking on the other side of the road (and the way streetlights around here seem to alternate one side to the other would seem to suggest that the intent is that one streetlight should help light the side of the road opposite to it), moving around in my garden is still going to activate the one closest to me.

Do any of the LED-lights mentioned in this thread actually have motion sensors (or does anyone have any other actual experience of this) that can give an indication of how they work in practice?

Thanks.

Edited by Demonperformer
  • Like 1

Share this post


Link to post
Share on other sites

Hertfordshire County Council have juts completed the upgrade of all A roads in the county to LED lighting.  The lights are centrally managed and will be dimmed during the night to save money, presumably based on the amount of traffic at the time determing the levels, so I'm guessing that some form of camera monitoring system, or if automated then through motion detection.  Here's a quote from the contractors site


Ringway, working on behalf of Hertfordshire County Council, has completed the upgrade of more than 12,000 street lights to LED lighting with a Central Management System (CMS) on Hertfordshire’s A-roads. The £6.5m project has taken eight months to complete. Ringway has an ongoing commitment to carry out dimming pilots; this includes a comprehensive consultation and three-month trial of A-road lighting to explore the possibility of further energy savings. Through the CMS system, street lighting maintenance will become more proactive, further enhancing the service to the council and residents alike.

LED (light emitting diode) lights considerably reduce maintenance costs, use much less energy than conventional lighting, improve visibility and reduce light pollution.

The new lighting is controlled by a wireless Central Management System (known as CMS), allowing the lights to be monitored from a central point. As faults are automatically reported, this reduces inspection costs and makes it easier to schedule repairs.

A-road lights were not converted to part-night lighting with other streetlights across the county, so remain lit all night. The new CMS system will allow lighting levels on the A-roads to be reduced during the night, rather than turning lights off completely. 

The project to convert A-road streetlights to LED lights cost £6.5m and will bring savings of around £660,000 each year from the end of 2015 onwards.

I can't find any info on plans to change local roads / b roads, so we still have a mixture of technologies and IMO if the new LEDs are cutting light pollution , then current LP filters would still work as only the older sodium light would be radiating upwards, but given that Herts CC have a policy to turn off street lights on local roads after midnight all I see is darker skies after midnight, and like others have commented, see the milky way more now from the centre of town than I used to.

Share this post


Link to post
Share on other sites

It's not spill or light directly radiating upwards from the fittings  that is the problem it's back scatter off the ground..

If you are unfortunate to have light coloured ground surfaces in the dry or shinny surface from dew, frost , snow  they cause considerable back scatter of what is at least around me exceptionally bright white LED light...

Peter...

Share this post


Link to post
Share on other sites

Peter, is the backscatter any worse than HPS lighting in he same conditions ?

Wet  roads will always reflect light more than a dry road.

Share this post


Link to post
Share on other sites

I have gone from predominantly LPS (we skipped HPS)  to LED  so for me the imaging situation is a lot worse as I have gone from easily filterable to something  you cant filter out !!!

Peter...

Share this post


Link to post
Share on other sites

I was attempting to build on some of the posts above:

#19 "when driving humans ideally need ... "

#25 "Driving through the lanes fitted with them ..."

But whether for cars or pedestrians, the distance at which the sensor operates would surely still be important. If it operates for pedestrians walking on the other side of the road (and the way streetlights around here seem to alternate one side to the other would seem to suggest that the intent is that one streetlight should help light the side of the road opposite to it), moving around in my garden is still going to activate the one closest to me.

Do any of the LED-lights mentioned in this thread actually have motion sensors (or does anyone have any other actual experience of this) that can give an indication of how they work in practice?

Thanks.

I understand there are motion activated systems being trialed in Denmark & Holland but these are meant to be triggered by cyclists and pedestrians AFAIK. I also expect the position and spacing of the lights is designed for the application of motion sensing.

Share this post


Link to post
Share on other sites

I mentioned above about there being new LED street lights being installed on our street. Well, it seems they are only on the street that runs across the end of ours and just one round the corner on to our street.

They are now powered up and the difference between them and the old sodium lights is breath taking.

I just took a quick snap with my phone camera:

post-28650-0-33703900-1444423395_thumb.j

The sodium lamp over the van on the left side of the road is typically dazzling and totally unshielded, much like all the lighting on the estate.

Over the red car in the middle distance and the car over on the right are two of the new LED fittings. Quite remarkable even when viewed through my poor photography.

The "footprint" of the LED lamps is very clearly defined and the the quality of the light by my eyes is rather "flat" compared to the sodium lamp.

It would be really interesting if those LED lamps were introduced across the Fylde my night sky would be much improved at least visually.

As it is, the few that have been fitted in this instance aren't going to change my sky very much. I don't have any direct sight of any street lights from the back. It's the sky glow from miles around that spoils it.

Edited by Paul M
  • Like 1

Share this post


Link to post
Share on other sites

This is probably for FenlandPaul. Since a lot of the problems of LEDs come from the residual blue exitation light would it be possible to use a fluorescent coating heavy enough to completely soak up the blue light leaving only a warm glow?

Share this post


Link to post
Share on other sites

This is probably for FenlandPaul. Since a lot of the problems of LEDs come from the residual blue exitation light would it be possible to use a fluorescent coating heavy enough to completely soak up the blue light leaving only a warm glow?

Hi Dave

I can't think why that wouldn't be possible (will check with our engineers - they know much more than me) but I suspect there are two main reasons it's not done. Firstly is the impact on the efficiency - the lumens per watt. Soaking up some of the precious photons on their way out would probably lead to a fairly inefficient chip, and the reality is that it would not be very competitive as a result. Secondly, the colour definition of white-light LEDs is a key feature; removing some of the blue light and creating a "warmer" look would reduce the perceived quality of light.

So I think it's possible, but not really marketable unfortunately.

Paul

  • Like 1

Share this post


Link to post
Share on other sites

Had an idea that'd be the case. All we can do is make the case for well designed lanterns with lamps that are only just powerful enough to do their job. "Only just enough, and only where needed", rather than the more usual "As powerful as we can afford, and anywhere we can put them"  :mad:

  • Like 3

Share this post


Link to post
Share on other sites

I live in a rural area and skies are relatively dark.  Cities to the north of my location present the usual sky glow.  I ski resort provides a horrible glow to the east in the wintertime.  Recently, the local elementary school installed new lighting that is so bright that it is like daytime when you are anywhere near the school.  From my "dark site" the view to the west is now wrecked by this lighting in the distance.  Thankfully, my view to the south has not seen any new lighting installed .... yet.

Light pollution is an ever growing problem everywhere and the new LED lighting is most certainly much more obnoxious.  I think that Astronomers must get involved to make the general public aware of the problem.  A nearby Observatory got involved when a local business applied to install new lighting.  Representatives from the Observatory met with the local government and the business owner and explained how the night sky would be affected.  The business owner agreed to install a different lighting system that would produce much less light pollution. 

My point is that we need to educate not only city officials and business owners about light pollution but even home owners.  For most homeowners, security lighting that is controlled by a motion detector would be just as effective as burning a high intensity light all night long.  

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.