F/Stop Question

Discussion in 'Photography Talk' started by wiseowl, Feb 11, 2013.

  1. wiseowl

    wiseowl Admin 24/7 Staff Member

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    Good morning ,could anyone tell me what the F stands for in F/stop,I have asked at my club and search the net and have come up with several answer's but not sure which is the accepted one.:scratch::)
     
    wiseowl, Feb 11, 2013
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  2. Dave W

    Dave W Total Gardener

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    I've wondered about this too Woo, but also have found no definitive answer.
    My best guess is that since the f stop is derrived from the ratio of aperture diameter and focal length and a convenient symbol was needed, the "f" from focal length was chosen. Just a guess though. It will be interesting to see any other explanations.
     
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      Dave W, Feb 11, 2013
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    • Scrungee

      Scrungee Well known for it

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      I thought the f in f-stop came from focal ratio.
       
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        Scrungee, Feb 11, 2013
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      • wiseowl

        wiseowl Admin 24/7 Staff Member

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        Hi Dave to be totally honest I only asked because a friend asked me as I was explaining his camera setting etc to him,and I didn't know:redface: :dunno: :)

        Hi Scrungee thank you my friend I have that among several answers ,I need to explain to my friend in layman's terms but the equations seem to be for Einstein graduates :)
         
        wiseowl, Feb 11, 2013
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      • wiseowl

        wiseowl Admin 24/7 Staff Member

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        Scrungee thank you with your Focal Ratio and the explanation below:)

        The f-stop is the focal length:dbgrtmb:
        I think it is safe to assume that f means Focal:dbgrtmb:




        Length Divided by Opening:phew:
        The f-stop is the focal length of the lens divided by the diameter of its opening. Each consecutive f-stop halves the opening of the previous. For example, an 80mm lens with its f-stop set to f8 means that the optics inside the lens create a diameter equivalent to 10mm. Changing the f-stop to f16 creates a diameter of 5mm.
         
        wiseowl, Feb 11, 2013
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