Are LED Street lights not so bad after all?

[Stephenstargazer]

My experience is that there are two different problems and the effect is not quite the same. The first is local lights (street, housing,security, sport facility etc) that dont get turned off. These can catch your eye and ruin your dark adaption whether directly or reflected. At the moment I am relatively clear of these but at the expense of quite a restricted sky area to work with.

 My problem is the second and less avoidable type which is the general urban areas and infrastructure in the 30- 50 miles around you. This lights the whole sky and reduces contrast. As long as most is sodium and mercury then LPR filters have some effect, but for visual use that can be self defeating. I have used EEA (video) to quite good effect on brighter DSOs such as galaxies which are otherwise impossible with an eyepiece. Those observing well away from such built up areas should count themselves fortunate.

It is a bit out of date (and optimistic)  but the Philip' Dark Skies Map from BAA Campaign for Dark Skies illustrates the latter problem well. LED lights are being put up to reduce power bills and councils and lighting contractors are trying to do it responsibly for local nuisance but the growth of infrastructure is relentless and more 24hr than ever.

[Stephenstargazer]

I just wonder how many of you were aware of or have contributed to this weeks star count ?

https://www.cpre.org.uk/what-we-care-about/nature-and-landscapes/dark-skies/star-count-2021/

[DaveS]

Thread on it already

[reezeh]

2 hours ago, wulfrun said:

It's perfectly possible to make them sodium-colour. Use yellow LEDs instead of white, it's quite a close match and I can verify that a UHC filter cuts it drastically.

Advantage: the LEDs would last several times as long.

Disadvantage: lower efficiency (not seriously so but lower all the same) and no improvement to colour-index. Saying that, we've managed for donkey's years with sodiums.

Indeed: why the insistence on colour index? Personally, I've always had a fondness for low pressure sodium yellow. The pure yellow colour I find appealing and it has the advantage of of being very easy to eliminate. I dislike high pressure sodium though as it is all over the spectrum so is harder to filter out. So LCDs that are true LPS yellow would be a boon.

[Cyril]

One of the problems we have had with LED replacements is that they have been fitted  to lamp post that have been there for forty year plus, the top is fixed and is tilted upwards, the one across the road lit the hillside behind us far better than the sodium lights, a word with the council, bless them, they fitted a hood.