Photographing street lighting


wasleys

Link Posted 04/10/2012 - 20:53
My son-in-law works in our local Highways Department. He has asked me to take some pictures of areas with different types of experimental street lighting. He will use the pictures in a presentation to councillors who will be deciding which type(s) of lighting to use in future.

This is way outside my experience but apparently nobody in the department can do it and they can't afford to adopt my advice to use the in-house photographers.

As the objective is to allow comparison between the different systems any post-processing (apart from cropping and straightening) is obviously out.

I will be using a K10 with a 16-45 lens.

After thinking about it I came to the view that the best approach may be to use P mode at ISO 1600 with AWB.

Further thought showed one drawback to that is it would not allow comparison of different light levels so it might be better to use M mode and a standard exposure of perhaps 1/5 at f4.

Any advice about the best approach would be welcome.
Last Edited by wasleys on 04/10/2012 - 20:54

Algernon

Link Posted 04/10/2012 - 21:10
Quite impossible I'm afraid depending on the exposure
you give you can make it look like daylight or midnight
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Algi

doingthebobs

Link Posted 04/10/2012 - 21:19
Is it the light levels they want to see, or the light colour, feel?

I would think the only way to do the light level is to measure, and come up with a value at different positions from the light source.

To show the difference in light colour you would need to fix the white balance not allow it to change.

To be honest, I think any pictures will modify the way the light looks. The counsellors will really need to go and see the lights for themselves.
Bob

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pentaxian450

Link Posted 04/10/2012 - 22:03
You should ask what they're looking for.

Do they want to see color temperature or light output?

For the former, you'll need to use a fixed white balance of approx. 5200 to 6000 deg. K.

For the latter, you'll need to show the light coverage, since the coverage is output dependant, so you'll need to put your camera some way out and, preferably, from some height, so the light coverage will be clearly delineated on the ground.

Needless to say it will show much better if cars aren't in, since their lights would ruin what you're trying to show.

They might also want a combination of coverage and light temp.

And you don't need ISO 1600. A good tripod is a must for such a project.
Yves (another one of those crazy Canucks)

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Mannesty

Link Posted 04/10/2012 - 22:14
AWB is a definite no-no in this situation if you want to compare the effects of the different colour temperatures of the various lights. AWB will try and make them all look the same.

Use daylight or cloudy WB setting.
Peter E Smith

My flickr Photostream

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wasleys

Link Posted 04/10/2012 - 23:18
Many thanks to those who have made constructive comments.

Frankly I'm not happy about doing this, it really needs input from a street lighting engineer (apparently not available at present) with proper measuring kit and a professional photographer (too expensive as already explained), however I have said I will have a stab and see what happens. I will be explaining the limitations to my son-in-law very clearly.

Yes, Bob is quite right in saying the councillors should get out on site, doubtless some will have done but I suspect others will not.

I doubt they will know what they want to know. I suspect they will be looking for a general impression of how it would appear to the driver or pedestrian so will be looking for a combination of light level, evenness of light and colour (at least that's what I'd want to see). I think we are talking residential streets rather than main roads.

Yves' point about a tripod is completely taken. I don't have one as I'm not into that sort of photography, only a monopod, so I think I will get the best result in terms of steadiness by wedging myself against something solid - hence ISO 1600 (yes, I know all this is a Fred Karno approach).

Peter, Yves and Bob all make the point about not using AWB and I had been coming round to that when thinking of a set exposure in M to avoid the 'grey' result of automatic exposure. From what I can make out the color temperatures of the lights involved vary from 1700 to 5000+. I'm assuming the recommendations to use WB of around 5500 are made as this will best show colour variations. Is that correct?

On the light level front the best I can probably manage are EV readings underneath and midway between lamps which should give some indication of level and distribution.

pentaxian450

Link Posted 04/10/2012 - 23:26
wasleys wrote:
Yves' point about a tripod is completely taken. I don't have one as I'm not into that sort of photography, only a monopod,

Check with your buddies to borrow one. It' a must.



I'm assuming the recommendations to use WB of around 5500 are made as this will best show colour variations. Is that correct?

Yes.



pentaxian450 wrote:
wasleys wrote:
Yves' point about a tripod is completely taken. I don't have one as I'm not into that sort of photography, only a monopod,

Check with your buddies to borrow one. It' a must.



I'm assuming the recommendations to use WB of around 5500 are made as this will best show colour variations. Is that correct?

Yes.





Yves (another one of those crazy Canucks)

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johnriley

Link Posted 04/10/2012 - 23:53
To be honest, the councillors need to do the job properly if they are making a decision that they hope will make any sense.

Having said that, if you do it then definitely fix the WB. Daylkight and JPEG capture would be close enough to show the variation. Tripod will be essential. As for exposure, you either fix that to compare lighting levels, or use the meter reading of the camera to expose "correctly".

If you don't know what they are trying to compare though it makes it all a bit vague to use to make spending decsions.
Best regards, John

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mikeyscope

Link Posted 05/10/2012 - 00:16
Local authorities are coming under increasing pressure to limit light pollution & save energy mostly in England & Wales so far...hopefully Scotland will follow sooner rather than later!

Sounds like your son-in-law's department is starting to feel the pressure from the drive in this direction, most likely they are looking for examples of good & bad lighting, efficient & non-efficient....everyone wants to see & feel secure in the street..... but nobody likes the streetlight that shines through their bedroom window at night!

Their main interest will be in light throw for streetlight spacing though colour temperature is important too, orange sodium vapour street lighting is slowly being replaced with white mercury vapour lighting and fall into three main forms...

(Globe Lighting) Found in shopping streets & supermarket carparks for example, covers wide areas but horrible light pollution, they often have black caps on top to help prevent lighting upward.

(Semi Cut-Off) Most sodium & mercury vapour streetlights are this type, less uplighting with lots of sideways coverage, not great in preventing light pollution or shining in bedroom windows but local authorities love them as lights can be spaced further apart.

(Full Cut-Off) This is the best type of lighting as all the light is directed downwards...at what angle depends on the lamp housing/reflector but spacing between lights is usually closer than semi cut-off, this is the type of lighting local authorities should be installing but probably don't as the initial expense of installation may be higher.

Try & go out on a night during a little mist or fog to clearly demonstrate the light throw of each type.

Here is a link you may find helpful, although astronomy orientated the issues are the same, as well as the interactive skyglow map there is an interactive lighting type/lighting throw demonstration you might find usefull as well as plenty links at the bottom of the page to lighting types/regulations/issues.(copy & paste link into your browser)

http://www.need-less.org.uk/

PS
Make sure your son-in-law pushes in favour of Full Cut-Off!

Mike
My Flickr Site

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andrewk

Link Posted 05/10/2012 - 00:19
In the dim and distant, I did have some limited experience in lighting design generally and a little in street lighting and area lighting using street lighting type fittings.

I agree with the comments about AWB. If you want to get an impression of the colour of the lighting, stick to a daylight setting. Some types of street lighting are completely monochromatic (low pressure sodium SOX lamps) - I don't know what AWB would make of those.

I still have a light meter (lux) and popped outside after reading wasleys original post to see if I could learn anything useful about the illuminance (lighting level - lux) provided by the new LED street lighting that was installed a month or so back. Directly under the a street lamp, the level was about 15 - 30 lux (EV 6-7) but midway between lighting columns was less than 1 lux, I know that because the meter read 0 lux - possibly EV -2 or even lower.

I don't know what the councillors really want to know about the experimental street lighting, but whatever it is they would be well advised to go and have a look, rather than rely on photographs, no matter how well considered they are.

If wasleys has a (photographic) light meter and can take readings in EV, then the conversion table at the bottom of this web page might be useful

Andrew
Flickr photostream
Last Edited by andrewk on 05/10/2012 - 00:35

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andrewk

Link Posted 05/10/2012 - 00:31
mikeyscope wrote:
Their main interest will be in light throw for streetlight spacing

Oldham and Rochdale have recently started to replace much of the street lighting in both boroughs (about 60,000 columns) with supposedly more efficient lamps types (LED, I think). Practically, in most cases, the contractors installed the replacement fittings on new columns in the same locations as the existing column, to minimise the cost of excavation, cabling and reinstatement.

As the new fittings seem to have far less sideways coverage than the old, low pressure sodium (SOX) fittings, the new lighting is very patchy in some places. They are also radio controlled (I think), at least they don't have a standard photocell on top - looks like a small radio aerial. Unfortunately, there is poor radio reception (and very poor mobile phone reception) in the cul de sac in which I live, so the two new street lamps never switch off. Isn't modern technology wonderful?

Andrew
Flickr photostream
Last Edited by andrewk on 05/10/2012 - 00:42

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wasleys

Link Posted 05/10/2012 - 01:42
Thanks to all for further comments.

@mikeyscope, Yes, my understanding is that all this is being driven by a commitment to reduce energy consumption on pollution grounds. I know that on some main roads LED lights have already been introduced but I have yet to see these in action.

@andrewk, My Polaris meter will give EV readings. Initial experiments in our street gave very low/out of range readings in some spots which suggests it might be better to increase the ISO setting on the meter and then scale back for any conversion to lux. But hopefully the authority will already have such figures.

timd

Link Posted 05/10/2012 - 12:19
Street lighting is quite an exact science. It is more than just lighting levels (as per a building) as most of the time the angle of illumination is not vertical. Glare and uniformity is a huge issue as well.

Quite honestly there are sophisticated programmes (Relux is what we use) to predict the final installation based on the photometrics of the luminaires. It is pointless getting a committee to "look" at a photograph and make a decision. Durability, reliability, resistance to insects and dirt as well as life cycle cost are also key.

Mickyscope - I hope that they are not re-introducing mercury vapour lamps. Those went out with the ark as they are inefficient and hazardous. Perhaps you mean metal halides as used in sport stadia floodlights.

It is debatable if Semi-cutoff and full cutoff is better as much of the light is reflected up from the illuminated roadway, especially when wet.

The beauty of low pressure sodium is that it is monochromatic and can be filtered out by any observatory. However high pressure sodium, metal halide and now LED, while less efficient than low pressure sodium, have higher outputs and are more environmentally friendly.

beakynet

Link Posted 05/10/2012 - 12:37
Two points from me:

1) ISO 1600 on the K10 is very limited and the results are likely to be very noisy, and not just in the shaddow detail. The other point with the K10 is the dynamic range is more limited so exposure will be more important and use of RAW advisable.

2) Fixing white balance may give you some issues, I would use a grey card and take a propper custom white balance reading for each shot. Or ensure that the grey card is included in the shot to allow for tuning of the white balance during post processing/RAW development. Without this, you will be guessing the Kelvin light value through the rear LCD!
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Mannesty

Link Posted 05/10/2012 - 12:49
beakynet wrote:

2) Fixing white balance may give you some issues, I would use a grey card and take a propper custom white balance reading for each shot. Or ensure that the grey card is included in the shot to allow for tuning of the white balance during post processing/RAW development. Without this, you will be guessing the Kelvin light value through the rear LCD!

Doing so would negate any colour temperature differences between the street lighting and render them looking all the same, similar to AWB. I don't think that is the objective of this particular exercise.

Taking a grey card reading in daylight and using that same WB for all of the street lighting exposures would be appropriate though.
Peter E Smith

My flickr Photostream
Last Edited by Mannesty on 05/10/2012 - 12:50

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