Chapter 3: Elements of Exposure, Aperture

The F-Stop setting determines how much light is allowed to enter a camera through the lens to reach the imaging sensor. F-stop is normally a setting of the lens that is attached to the camera, and is controlled mechanically, by opening or closing the lens aperture . 

 Different lenses have different apertures and so can handle different f-stop ranges.  

 The  Canon EF 24-105mm f/4L IS II USM lens that is normally kept on the SCiL DSLR cameras has an adjustable f-stop range from f/4 (wide open) to f/22 (nearly closed). It will retain the f-stop you set through its entire zoom range from 24mm to 105mm. 

 When the camera is set to video mode , you can set the f-stop on the Canon EOS 5D Mk IV using the  large dial around the "set" button located at the lower right of the camera body. 

 

 Lower f-stop numbers (like f/4) indicate that the aperture is more open , allowing in more light . 

 Higher f-stop numbers (like f/22) indicate that the aperture is more closed , a llowing in less light . 

 

 F-stop settings influence the  depth of field . 

 f/1.2 - f/2.8 - lets in a lot of light , with a correspondingly shallow depth of field . 

 f/4 - f/8 - useful in many scenarios, with a somewhat wider depth of field . 

 f/11 - f/32 - best for bright settings , with a wide depth of field . 

 

 In the chart below, see how different  f-stop settings change the amount of light reaching the sensor and the depth of field :