Civil Twilight

Morning civil twilight begins when the center of the sun is 6º below the horizon (-6º) and ends at sunrise. Evening civil twilight begins at sunset and ends when the center of the sun reaches 6° below the horizon (-6º). Learn more on Wikipedia.

Compass

Instrument for determining directions (azimuth), as by means of a freely rotating magnetized needle that indicates magnetic north. Learn more on Wikipedia.

Crop Factor

The ratio of the sensor format relative to a 35 mm frame. Learn more on Wikipedia.

Circle of Confusion (CoC)

It is the largest on-film/sensor circle that you can see as a well defined point on an 8''×10'' print when viewed at from a "normal" viewing distance of 2 to 3 feet. Anything larger is seen as a small circle, not a point and is therefore perceived as out of focus. Learn more on Wikipedia.

Clip Length (Time lapse)

The desired length of the video clip that portrays the event.