Moonlight has a color temperature of 4100K, while sunlight has a higher color temperature of more than 5000K.
But objects illuminated by moonlight don't look yellower to the eye. They look bluer. This holds for indoor scenes (like my hall) and for outdoor. I find it counter-intuitive that moonlight has a lower color temperature. I thought the sun is the yellowest natural source of light we have.
Is that because of the poor color sensitivity of the eye in dim light? In other words, moonlight is actually yellower, but our eyes can't see the intense yellow color?
If one were to use a giant lens to concentrate moonlight to reach the brightness of sunlight, will objects illuminated by this light appear yellower to the eye than the same objects under sunlight? Has anyone done such an experiment? I looked, but couldn't find any.
Alternatively, if I take a long-exposure photo of a landscape illuminated by the full moon, and another one illuminated by sunlight, and equalise the white balance and the exposure, will the moonlit photo look yellower?
Answer
I took a photo during the day, at 2PM:
I took photo at night (4AM) of the same scene, lit by the full moon. This is a long exposure photo (30 seconds) with roughly the same exposure:
I adjusted its color balance to match the day photo (temp=5100 and tint=+3 in Lightroom). The moonlit scene has a strong yellowish color:
This proves that moonlight indeed has a lower color temperature. It's not a slight difference in color, but a huge one.
This experiment excludes the effect of the:
- blue sky making things on the ground look yellow in comparison (because there's no sky in this photo, and the color balance is set to the same for both photos).
- eye being unable to perceive colors or perceiving them wrongly (Purkinje effect) when it's dark.
- sun or moon at horizon (because they are high in the sky for this photo)
No comments:
Post a Comment