Archived posting to the Leica Users Group, 1999/07/27
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Alex asked: What does the 'f' in f-stop stand for? (I've asked people and looked in books, and had to admit to the person who asked me - haven't got a clue!) According to the Ilford Manual of Photography, relative aperture is the relationship of the focal length of the lens divided by the diameter of the effective aperture. N=f/d. "The numerical value of relative aperture is usually prefixed by the letter f and an oblique stroke, eg f/8. The letter f and the stroke serve as a reminder of the relation between relative aperture, effective aperture and focal length. The relative aperture of a lens is commonly referred to as its f-number" Really not an explanation for Alex, you would think by this we should be talking about "N" stops instead :) Noel Charchuk