technique - How do you make a shot look like it was taken at night?

Okay, so I was watching a movie recently, and there was a night scene. The whole valley could be seen in light, and there were some stars as well, and the actors could be seen, but it just looked like it was night. How do you make a shot look like it was taken at night, especially if there is no signs of civilization around?

Answer

The effect is called day-for-night and it's particularly common in old movies.

In old movies it can often look pretty unconvincing, but more modern techniques, and stills instead of motion picture, can improve this.

Counter-intuitively, often the more authentic-looking examples of night light heavily use artificial lighting.

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  It's often characterized by a blueish hue - this can be achieved by white balance - and by underexposure. Boosting the contrast may help too.

  
  


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  Sometimes, day-for-night involves very powerful lighting setups where the lights "overpower" the sun and can provide local highlights. This can be quite effective if done well.

  
  


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  It's often better just to actually shoot at night, or at dusk/dawn, and use lots of side/edge lighting.

  
  


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  Post-processing can be useful in dampening the bright sky (though it's often best to just avoid including any sky) and removing highlights from clouds, etc which are dead giveaways.