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I am into night photography, and am looking at buying a polarizing filter. What particular advantages and challenges are there to using a polarizing filter at night?

  • reflections from light on materials if it rains: does it decrease the "wet look"?
  • reflections on glass: do they disappear as in the daytime?
  • does it change the star shape of lights?
  • does it create extra glare and flare on lights?
  • does it remove glare from water or long exposure (10min) on the sky?
  • Its been 6months since your question. I would love to hear about your experience. Did the polarizing filter help? – BiGYaN Aug 14 '15 at 18:43
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A polarizer can make some reflections disappear or, if rotated 90 degrees, it can make the reflections stronger. In general, transparent materials, like window glass, water and even air, affect the polarization of reflections, but metallic reflectors do not. So, in answer to your questions:

  • Depending on rotation of the filter, it can increase or decrease the "wet look".
  • It depends on the filter orientation if glass reflections are eliminated or exaggerated.
  • It should not change the shape of lights.
  • A good, clean filter should not create much extra glare or flare on lights.
  • It can remove glare from still water, but is less effective on ripples.
  • It can darken and intensify the color of the sky at 90 degrees from the sun on a clear day. At night, it might have the same effect for moonlit scenes.

Why not buy an inexpensive polarizer for your camera and experiment? Keep in mind that it decreases light by about two f-stops, so can increase noise in a digital camera or induce reciprocity failure with emulsion photos.

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To be honest, the advantages of using a polarizing filter at night are limited. The vast majority of people who purchase a polarizing filter are using it to darken the sky for landscape photographs. Others may also use it to remove reflections in glass or water (or general glare from photographs).

  • It will only decrease the "wet look" or have no impact at all. It will not increase reflections.
  • Same effect for reflections as during the day -- only the light source is different (moonlight, artificial light) versus sunlight.
  • No change to the shape of the stars
  • Should not with a clean, high-quality filter
  • The effects on water will not change -- we're only talking about the light source (same comment as reflections above). However, it will not intensify the colour of the sky. Polarizers do not "make the sky bluer" (although that's how it may appear to us) -- they darken the skies relative to other objects in the frame. At night, the sky is no longer blue and so in this regard a polarizing filter's only effect will be to darken everything... (essentially acting like a 2-stop ND filter).

However, with that said (as pointed out above) you've got to remember that even the best polarizing filters will block 1-2 stops of light, meaning that you will have to compensate to get the exposure back to "normal" which will often mean increasing the ISO at night -- and the impact on image quality from doing so may marginalize any small benefit you get from using a polarizer.

  • Please be explicit about what part of the question you are answering. – damned truths Mar 2 '15 at 7:25
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Although this has an accepted answer, I would like to add my two cents.

I wouldn't recommend using a polarising filter for night photography. This is because:

  • It reduces the exposure. In dark conditions, you normally want to have a reasonably sharp aperture and as low an ISO you can get away with for the desired exposure. A polariser may force you to open the aperture - getting a less sharp image, or increase the ISO - getting a more noisy image.
  • As a rule of thumb, adding more glass reduces image quality. Unless you keep the filter very clean, you may see extra lens flare or dust specks if shooting a scene with bright lights, e.g., the full moon or street lights.

Having said that, there may be some use for a polarising filter. You might want to reduce/increase the reflection of the full moon on a lake, for example. Or maybe you need a longer exposure time at dusk for traffic trails. Maybe if you've got a bright, moonlit scene, you can get a similar blue-sky darkening effect as you get during daytime (this will work at night because the Rayleigh scattering in the atmosphere is exactly same - the sky is blue at night too but there's so much less light).

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