A trip down sodium street light lane

I’d been toying with the idea of taking some pics under Ye Olde Sodium Street Lights (the LP or low pressure type) for a while, and suddenly realised the crazy days of DST (or whatever) were almost upon us again, and I would soon have to go out late if I wanted to play this game.

The reason I hadn’t managed it sooner was simply a matter of not having though of it sooner.

There are now very few streets left that have not been converted to LED, were already fitted with white fluorescent lamps, or have had most of their light replaced by LEDs when old lamps failed and were replaced.

I couldn’t find a complete street of sodium lights as they all seemed to have at least one, and usually a lot more, white lights dotted along their length.

I’d almost given up, or thought I’d have to go for some long walks (or rides in better weather), then literally turned into a nearby street and realised I was looking at what I hadn’t been able to find when I was out hunting.

The sodium lighting issue

I suspect most people are unaware of the simple fact that a (low pressure) sodium light emits just one single colour of light (well, two actually, but the two are so close as to make no difference for our purpose here). This makes it quite different from white light, which is a mixture of all the colours of the spectrum, and why white balance is critical. Again, that’s another story.

However, the biggest effect this difference can have on photographs is that while a colour pic taken under white light can be edited to correct or alter its white balance (since it contains all the colours that made up that original white light), the same is not true of a pic taken under sodium lighting. It contains yellow, and ONLY yellow.

I remember the first time I tried to apply colour tools to a street pic (taken on film, of course) – and the sledgehammer of enlightenment struck hard as everything failed, and I realised how stupid I had been.

After all these years, I was curious to see how such pics looked using digital cameras.

Back in the film days, I just didn’t shoot colour in the dark. It was usually a waste of time since everything was going to be yellow. B&W was simpler, and usually looked better.

I wasn’t out to do anything clever with these pics, just see how they looked, and if playing with setting made any great difference.

Bear in mind I don’t use a tripod/support, so rely on tech wizardry for my low light hand held pics.

In terms of processing, all the pics received a similar amount of boost to raise shadow detail only, and a slight reduction in the exposure around the street lights themselves.

Although I didn’t include an example (I think it looks pretty bad now), I did throw these through the auto adjustment tool I was stuck to a few years ago. It effectively just lifts all the shadow and mid-range details far too much, and is not adjustable. It’s good, just not subtle.

I think it used to be acceptable in those days because the camera sensor I had back then wasn’t so good or sensitive as those I use now.

No need for me to include B&W or greyscale versions – if you’re that keen, it’s easy to do online now.

I lost the closest street light, to see how it affected the overall exposure.

Raising more shadow detail – this can wash out areas and lose detail if overdone.

I just moved along a bit in order to catch the lit house, and catch the difference when there is a genuine white light illuminating part of the scene.

The last shot is just the same street, but from the other end.

The exposure of the street lights seems to have been noticeably different compared to the first shots. No idea why. I can’t really see that much difference in the rest of the scene.

It’s funny looking at the ‘Pics from the past’.

Apparently, some people like this effect so much they’ve been complaining about white/LED, and campaigning to have sodium street lights restored.

They’re welcome to it and, I suspect, their scratchy clicking vinyl records too.

I’ll go with all the modern, improved versions.

That weird pic from Ibrox – updated and explained

I couldn’t wait for this analysis, so had to make a special trip back to Ibrox on a dry and su… (well, one out of two will do) day, to see why this pic was so weird.

A quick reminder – I couldn’t remember what this looked like to the eye, and when I applied colour correction tools, they didn’t have any effect (unless I’d wanted some sort of psychedelic result).

I was amazed to see what this looked like in daylight, and a look around the area quickly provided the reason for the difference, which was obvious.

The late night, low light original (which was taken under conditions MUCH darker than the pic might suggest), was found to have been illuminated by a mix of street lighting from the surrounding area.

Only one street light appeared to have been converted to LED (i.e. white), while everything else was either low pressure sodium, which produces a single yellow at around 589 nm, or high pressure sodium, which produces a wider light spectrum, and has a peak around 570 nm, which just happens to correspond to my initial analysis of the original pic, which showed a load of green content.

It seems, to my eyes at least, the LP sodium provided most of the light, as the pic looks like the sodium yellow of the ‘Good Old Days’, while the colour analysis saw mainly the green peak of the HP sodium.

That small sign on the left caused some confusion. Such things are usually white, and can be used for correction – but if they actually turn out to be yellow, then they’re no help at all.

That’s an interesting effect I hadn’t come across before, as most streets with sodium lighting tended to have either LP or HP fitted throughout, and not mixes, as seen at this location.

The single white LED luminaire provided no real contribution to this scene – unlike most sodium luminaires which spew their output in all directions with little effective control, the LEDs only illuminate the area below, rather than all around (and above!).

Interesting – it’s so long since I’ve come across street lighting that is almost wholly sodium, it had almost slipped my mind.

But what an excellent example of the non-existent colour rendition of sodium lighting as compared to daylight, white LED, or the fluorescent white street lighting which appeared in some areas.

Just for the sake of completeness, I caught the whole wall, including the section to the right, where there isn’t really much to see.

Since I’m in a good mood, here is the text from the right:

THAT ONE CAN GIVE WHAT ONE DOES NOT POSSESS – OH THE MIRACLE OF EMPTY HANDS

Unfortunately, what appears to be a signature towards the lower left corner may have a little damage, and is not so clear, so this may be wrong. Also, there seems to be no word spacing, making it hard to read.

FAITHEARTYSEVEN

A little game you can play as the nights draw in

While I’ve never asked anyone about this, I suspect my thoughts are likely to be correct about this.

Referring to the pic below, it should be fairly obvious that the street lights caught in the shot are different.

One is fairly (very) yellow, while the other is white, but is NOT a new LED street light.

The yellow light is a standard low pressure sodium type, used around Glasgow (and the rest of the country of course) for years.

The white light is fluorescent type once common, but eventually phased out.

I know that because a found a web site dedicated to such things a few years ago, when I first noticed these lamps appearing.

Sadly, that web site has gone, but at least I took this quote at the time I found it.

By the 1980s, the fluorescent street lighting lantern was becoming a rarity. Installed on the wave of post-war rebuilding, the original fluorescent tube (born during the war years) was an exciting and practical light source for the 1950s and 1960s. Although far more expensive than lanterns for other bulb types, the fluorescent lantern offered a natural warm light and a wide beam which was good in both the wet and dry. Unfortunately these multiple tube monsters sucked up too much power, were too complex to keep running and simply cost too much to maintain. Throw in the energy crisis of the 1970s and fluorescent street lighting had only limited time left on the streets of the UK.

However, it seems that these continued to be developed for a while, and although they were never adopted, they were around for a while, used in many places, and it seems there are still stores full of spares.

Wandering around Glasgow housing schemes, I have found entire streets still lit by these types.

More intriguing are the (increasing) number of streets I find where failed LP sodium lamps are being replaced by these fluorescent type.

My guess is that Glasgow (and presumably others) are mitigating the cost of LED conversion on main roads by ending purchases of any new LP sodium bulbs, and digging into piles of unused spares when they need to replaced failed lamps, either with a similar LP sodium if available, or with one of these white fluorescent types.

I’m spotting more of them making an appearance nowadays, instead of a yellow sodium lamp when dead lamps are replaced.

You can play the same game if you’re wandering around as the darker evening arrive.

Fluorescent Vs Sodium

I couldn’t quite climb up for a look at the label inside the luminaire, but I did manage to take a pic from below, to get the details.

Although the year is not clear in this pic, it did appear as 2013 in others, but they were less readable overall.

Label

These white lights – remember, they are NOT LED types – are becoming more common, so you should be able to find them somewhere.

There are a couple of features I couldn’t catch in a pic to illustrate them, they just don’t show up in pics taken from the ground, but they are noticeable.

Unlike sodium lights, the covers are made of ‘water clear’ plastic, and have no lenses to shape or direct the beam.

They are very bright, which may be down to the phosphors used in the tubes, but is also due to the lamp having two tubes, although it just looks like a single tube when seen from below. The tubes are usually mounted vertically, one over the other, but more recently, I have come across some which appear to have the lamp mounted on its side compared this, so the tubes are aligned beside one another.

Sometimes they sneak up on you, and watch you looking for them from behind hedges (and there’s also a sodium in the background).

Fluorescent And Sodium

But we’ll still give them their ‘Glam’ shot.

Fluorescent Closeup

Glasgow lighting elves must be emptying the spare lighting stores

Noticed a funny thing a few weeks ago, while cruising the back streets of Shettleston and Sandyhills.

Along with the bigger main streets, these are beginning to see a slow roll-out of new and upgraded hardware.

While the main roads have seen a 100% commitment to LED upgrading, lesser streets seem to be benefiting from an upgrade to many of the ancient lampposts standing in them, but not to a 100% LED upgrade.

This probably makes a deal of sense. Many of the posts must be decades old, and are made of ferrous stock, or the more interesting reinforced concrete.

In either case, these relics are, sadly, suffering the effects of Scottish weather and their age. Many metal poles are now showing advanced corrosion, and the concrete type are failing as the surface concrete lets water in to the reinforcing steel rods within. These corrode, blow off their concrete protection, and accelerate the corrosion process.

While I’ve never seen any of them just collapse, I have seen a number of lesser posts on road signs suffer corrosion to the extent that they have become weak enough to collapse from their own weight, or have just been pushed over.

Now that it’s getting dark early, I get to play with low light hand held pics again.

I’d almost forgotten about the back street lighting updates. This work seems to be carried out by the Street Lighting Elves, since I’ve never seen it actually happen, just see the changes when I pass during the morning after.

But dark nights mean I can see the ‘new’ lights in action, and this confirms an earlier observation that the lights fitted to the new poles appeared to be chosen at random, and are not a general changeover to LEDs.

A couple of view along one street show the effect.

In the first, looking along the left side of the street we have: fluorescent, sodium, sodium, fluorescent, fluorescent; and along the right: LED, LED, fluorescent, LED.

I’m still pretty sure they’re using up existing stock, rather than discarding it, as the upgrade progresses.

Odd Street Lighting Upgrade 1

In this view we have along the left: sodium, fluorescent, sodium, sodium, fluorescent; and on the right: LED, LED (this IS lit although it looks as if there is no light on this pole, spot it in the first pic), fluorescent.

Odd Street Lighting Upgrade 2