Importance of Moonlight

Just as how daylight photographers pay attention to the position and angle of the sun, night photographers should also pay careful attention to the moon. A low-laying moon can create long shadows on cross-lit objects, whereas an overhead moon creates harsher, downward shadows.

An additional variable is that the moon can have varying degrees of intensity, depending where it is during its 29.5 day cycle of waxing and waning. A full moon can be a savior for reducing the required exposure time and allowing for extended depth of field, while a moonless night greatly increases star visibility. Furthermore, the intensity of the moon can be chosen at a time which provides the ideal balance between artificial light (streetlamps) and moonlight. Gauging exposure times during a full moon can be tricky; use f/2.0 and 30 seconds at ISO100 as a starting point (if subject is diffuse and directly lit), then adjust towards scenarios 1-4 accordingly if OK. Another factor rarely noticed during daylight is movement of the light source (sun or moon). The long exposure time required for moonlight photography often means that the moon may have moved significantly over the course of the exposure. Moon movement softens harsh shadows, however too much movement can create seemingly flat light.

Photograph Under a Full Moon

Note how the 1 minute exposure above clearly shows high contrast and shadows from even the smaller branches, whereas the 4 minute exposure is at lower contrast and only shows the larger branches. The choice of exposure time can also vary by much more than a factor of four-- greatly exaggerating the above effect.

Crop of Tree Shadows on Path:

Choose Exposure Time:

Photograph Under a Full Moon 1 minute 4 minutes  

Shots which include the moon in the frame are also susceptible to moon movement. A rule of thumb is that the moon appears to move its own diameter roughly every 2 minutes. As a result, it can quickly appear elongated if this exposure time is approached.