What is an f stop

joshhuntnmjoshhuntnm Registered Users Posts: 1,924 Major grins
edited April 15, 2008 in The Big Picture
I know it measures how big the aperature is.

I know the lower the number the bigger the opening.

I know the lower the number the narrower the depth of field.

Here is my question: what is it actually measuring? When we refer to a 2.8 lens, 2.8 what? And why is the bigger number the smaller opening? A bit of trivia, I know, but just curious.
Josh
Las Cruces Photographer / Las Cruces Wedding Photographer
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  • DI-JoeDI-Joe Registered Users Posts: 368 Major grins
    edited April 15, 2008
    joshhuntnm wrote:
    I know it measures how big the aperature is.

    I know the lower the number the bigger the opening.

    I know the lower the number the narrower the depth of field.

    Here is my question: what is it actually measuring? When we refer to a 2.8 lens, 2.8 what? And why is the bigger number the smaller opening? A bit of trivia, I know, but just curious.

    f stop is a function of absolute aperture size and focal length.

    check out this great article.

    http://www.uscoles.com/fstop.htm
    Modus Imagery
    Moving away from photography and into cinema. PM me if you have questions about DSLR workflow or production questions.
    Film Reel: http://vimeo.com/19955876
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