Let there be dark

The Shot
The same scene captured four times in the space of half an hour as ambient light levels changed.

Effects of four different styles of ambient light

Four stages of illumination (click for hi-res)

The Story
a) ISO400, f/4, 1/13 sec
With floodlights on, the building is illuminated; the streetlight is visible but having negligible effect on the ambient light; the sky is very dark with no stars visible. This is close to how our eyes would perceive this scene.

b) ISO400, f/4, 1/13sec
The streetlight remains on yet with camera settings the same, such is the change in brightness once the floodlights go off there’s now insufficient ambient light to record an image.

c) ISO400, f/4, 30 sec
Adjusting the camera settings for ambient light, the streetlight becomes by far the brightest object within the scene. Its glow casts a haze well into the sky, hindering our limited view of the stars. Despite the neatness of the four frames above, I didn’t actually capture them with this comparison in mind so for consistency I used PhotoShop to add +1ev to this frame to bring it in line with the exposure value of the frame alongside. There’s no photo manipulation going on here, though.

d) ISO800, f/4, 30 sec
Finally, with the immediate streetlights out, the scene’s lighting becomes more balanced. The building is picking up light from distant streetlights but our night sky view has finally been fairly well revealed. After just a few moments in this darkness our eyes would adjust so, again, this is close to how our eyes perceive the scene (although it’s fair to say the darker it gets, the more monochromatic our vision becomes).

The Tip
Take time to look around you at the way buildings are lit at night. With light comes contrast. The brighter the object on which you’re focused, the darker its surroundings appear. In the series above, the stars were there all along- there was just too much contrast to be able to record them in the same scene as the lit building. The same is true at ground level- dark shadows seem so much more intense when you come to the end of a brightly lit area.

Whilst it’s great that in this instance the floodlights went out eventually, unnecessary lighting does much more harm than good, to our immediate vision and our long-term health. I’m determined to do all I can on a personal level to raise awareness of light pollution matters. If you too feel like making a difference, the International Dark Sky Association has some great resources for looking afresh at light pollution and understanding more about its detrimental effects.

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