First Quarter

This phase occurs when one-half of the moon is illuminated by direct sunlight. The illuminated part is increasing. The moon squares the sun. Learn more on Wikipedia.

Full Moon

This phase occurs when the visible moon is fully illuminated by direct sunlight. At the full moon, the sun and moon are in opposition. Learn more on Wikipedia.

f-number or f-stop

International sequence of numbers, expressing relative aperture, i.e. lens focal length divided by effective aperture diameter. Each change of f-setting halves or doubles image brightness. Learn more on Wikipedia.

Film speed

The measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system. Learn more on Wikipedia.


Transparent lens attachment used to modify the light coming into a lens, to change the color, or other characteristics of an image. They are used both on the camera and in the darkroom. Learn more on Wikipedia.

Focal Length

The distance (in mm) from the optical center of the lens to the focal plane. Learn more on Wikipedia.

Field of View (FoV)

What is visible through the camera-lens combination at a particular position and orientation in space. Objects outside the FOV when the image is made are not captured.
Field of view is expressed in linear measurements (meters, mm; feet, inches) for a given working distance. Learn more on Wikipedia.

Focal Length Horizontal/Vertical

It refers to the focal length needed to match horizontal or vertical angle of view.

Frames Per Second (fps)

The number of frames per second in your video. For example, if you have selected 25 fps you will need 25 photographs to generate one second of video. Learn more on Wikipedia.