Aukkoluku

Aukkoluku is a Finnish term that translates to "hole number" or "aperture number" and is commonly used in the context of photography. It refers to the diameter of the lens's aperture, which controls the amount of light that reaches the camera sensor or film. This is often expressed as a ratio of the lens's focal length to the aperture diameter, denoted by an 'f-number' (e.g., f/2.8, f/8, f/16).

The aukkoluku is a crucial setting for photographers as it directly impacts two key aspects of an image: exposure and depth of field. A larger aperture (smaller f-number, e.g., f/1.8) allows more light to enter the lens, enabling shooting in darker conditions and creating a shallow depth of field, where the subject is in focus and the background is blurred. Conversely, a smaller aperture (larger f-number, e.g., f/16) restricts the amount of light, requiring more light or a slower shutter speed, and results in a greater depth of field, where more of the scene is in focus.

Understanding and manipulating the aukkoluku is fundamental to achieving desired photographic effects, from isolating subjects with creamy bokeh to capturing sharp landscapes with everything in focus. It is one of the three pillars of the exposure triangle, alongside shutter speed and ISO.