copytriada.blogg.se - F stop photography definition

Welborne Piper first proposes a unified system of describing aperture marking called the 'f-diamater' (or fractional diameter) after observing similarities between a half-dozen of the more popular methods of the day. Hodges first champions the 'fractional number' system (which he abbreviated to 'F-number') in defiance of the Photographic Society of Great Britan's use of the 'Uniform System (U.S.)' This is the first recorded instance of the 'fractional number' and is likely the original meaning of the 'f' in F-stop. This is likely the first instance of the use of the word 'stop' as it relates to aperture. He called them ' Waterhouse Stops' because the discs were literally stopping light from entering the camera. In 1858 John Waterhouse invents a system of metal discs with different sized holes to act as the aperture which literally get dropped into a slot in a lens.

(Well-known systems at the time included Sutton and Dawson's 'apertal ratio,' and Dallmeyer's 'intensity ratio')

In the late 1800's there were a variety of aperture systems which all operated more-or-less the way we are all familiar with, which is to say that the concept of letting more or less light through a lens via an aperture system was being used extensively, even if the different systems used different naming conventions.

The Wikipedia F-Number article actually has a rather complete (and well cited) history of how we got here, but some of the 'high points' are:

Finestra Stop (Finestra is Italian for 'window')Īs with many historical 'facts,' the truth is quite a bit messier than many of these sources would seem to indicate, and the real reason that we use 'f-stops' today to some extent defies a quick explanation.

This is a matter of some debate, and the truth is that you can pick up any number of photography books (or visit any number of photography websites) and read a variety of answers to this question, the most common of which tend to be: