Aperture (DE: Blende)

updated: 2021-08-109

Aperture, or f-stops, is the relation between the area over which light can enter your camera or CMOS or CCD chip and the focal length of your lens. 

Aperture symbol

Aperture Unit




B = Fob/d


Fob = focal length of the lens in [mm]

d = diameter of the lens or telescope in [mm]

Other important factors of the exposure triangle are:

  • Exposure time: has an impact on sharpness of moving objects
  • ISO speed or gain: is the sensitivity and has an impact on the grain or noise
  • (Filters: reduce the sensitivity and require changes in the exposure triangle)

Lower f-stop settings (such as F5.6) have a larger diaphragm opening, allowing more light through the lens. 

On the other hand, Higher f-stop settings (such as F11) have a smaller diaphragm opening, allowing less light through the lens

The aperture settings on cameras are commonly referred to as f-stops and have a specific numerical sequence, such as: F5.6, F7.1, F8, F11 and go in sqrt(2) sequence.


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