Summary of the effects of the parameters in the Exposure Triangle

Primary Effect Secondary Effect(s) Tertiary Effect(s)
Shutter Speed Control the amount of time the sensor is exposed to light Blurring or freezing of subject in motion Rolling shutter
Aperture Control the amount of light from the scene that hits the sensor Depth of field/Bokeh Diffraction; Starburst
ISO Control the sensitivity of the sensor to light Noise (grain)

One of the more puzzling and confusing aspects of this (and the motivation for me to write this manuscript) is how the secondary effects of the legs of the exposure triangle change with sensor size.   A full explanation of how this works requires that we bring in the definition and meaning of “focal length”.

Another time.