A&P Aperture Math

Discussion in 'Lifestyle' started by hurleyint1386, Sep 22, 2008.

  1. hurleyint1386

    hurleyint1386 Someone has sand in their vagina

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    I've been looking at some f/stops and I've been thinking, there must be some kind of math behind it. I can't seem to find the pattern between 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, 45... etc I know it can go up to 256 (pinhole) but I was wondering where I can find out the math for this. Or are they just common f/stops with no pattern?
     
  2. wizeguy4

    wizeguy4 New Member

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    http://www.uscoles.com/fstop.htm

     
  3. hurleyint1386

    hurleyint1386 Someone has sand in their vagina

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    Awesome, thanks a lot.
     
  4. Tedrzz

    Tedrzz New Member

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    they are roughly half of each other, and each time you go to the next smaller (in physical size) f-stop it will change your exposure 1 whole stop if you didn't adjust anything else.
     
  5. hurleyint1386

    hurleyint1386 Someone has sand in their vagina

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    That stuff I knew. I was just curious about the math between 1.4, 2.0, 2.8, 4, etc because 1.4 doubled isn't 2.0, and 2.0 doubled isn't even roughly 4.0 because 4.0 is 2 stops above 2.0. But with the ratios, it makes more sense to me.


    Are you the guy that lives 3 blocks away from me? :noes:
     
  6. Tedrzz

    Tedrzz New Member

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    no i think that was the other dude, i live on elmwood
     
  7. hurleyint1386

    hurleyint1386 Someone has sand in their vagina

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    Still only a couple miles away! Rochester OTAP meet?
     
  8. DR-GSR

    DR-GSR Old Member

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    fstop x sq root of 2 = next f stop

    1x 1.4 =1.4
    1.4 x 1.4 =2
    2x 1.4 =2.8

    etc
     
  9. NetChemica

    NetChemica OT Supporter

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    F stop * 1.4142135623730950488016887242097 = next f stop.


    pretty easy to remember :)
     
  10. QWIKSNK

    QWIKSNK New Member

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    think about it in 2 stop increments..

    1.4 -> 2.8, 2.8->5.6, 5.6 -> 11

    2 -> 4, 4 -> 8, 8 -> 16
     
  11. David

    David New Member

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    So, using that math thingy, how does f/.95 work if you had a 50mm lens, wouldn't the diameter of aperture have to be like ~53mm?
     
  12. QWIKSNK

    QWIKSNK New Member

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    I believe so... so the front element would have to be at least 60+mm

    remember, the size of the lens has nothing to do with its focal length. There are some decent sized lenses with not a lot of reach, and some small lenses with a lot of reach (I hope that makes sense)
     

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