Manual Photography. Aperture and Shutter Speed: Here’s how they relate to each other for correct exposure.
Your camera is a box with a hole in it.
The Aperture is in the lens. It is the hole. The ‘f’ you read on a lens, for example 3.5 to 5.6 is the size of the hole.
It is the focal ratio.
It is the focal length, e.g. 50mm divided by the diameter of the hole.
So if the Aperture hole is 25mm then 50/25 is 2 and we would say that your aperture…