can anyone suggest easy to undertand fStop reading online

Discussion in 'Photography Beginners' Forum' started by 8ball, Sep 2, 2010.

  1. 8ball

    8ball TPF Noob!

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    can anyone suggest easy to undertand fStop reading online
     
  2. inov8ter

    inov8ter TPF Noob!

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  3. BuS_RiDeR

    BuS_RiDeR No longer a newbie, moving up!

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    Warning: VERY basic explanation.

    The higher the /f number... the more is in focus...
    High f number = smaller diameter of the aperture in the lens...

    for example...

    If you have an aperture setting of f1.8 (assuming your lens can do it)... Then your focal point will be in focus, while things in front of and behind your focal point will be out of focus.

    If you have an aperture setting of f12, then more of the scene in front and behind will be in focus...

    If you have an aperture setting of f22, then even more of the foreground and background will be in focus...
     
  4. MrBarney

    MrBarney TPF Noob!

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    After writing this, I'm not sure it came out as simply as I'd hoped. Never mind...

    Think of the aperture as a circle and the f number as a fraction. You are changing the size of that circle. I find it easier not to read it as f/2 or f/4 - instead read "one half (of the theoretical maximum diameter)" or "one quarter" (or one eleventh, etc.)

    Each "stop" of light is a halving or doubling of the *area* within the circle, which is why the numbers for each stop aren't linear - the relationship between the diameter and area of a circle is not linear. This is how you control the exposure (along with shutter speed and ISO).

    A "side effect" of changing the size of this circle is that it is one of the parameters that defines your "depth of field". The other factor you have any real control over is the focal length. Time for another explanation!

    If you ran a tape measure from the camera off into the distance, you can focus the lens at pretty much any point on that tape. The depth of field is the distance in front and behind that point which is also "acceptably" in focus. The smaller the aperture circle (smaller *fraction* - 1/11 is smaller than 1/4), the larger this area is.

    Why do you care? Well, imagine you have a group of people at differrent distances from the camera, you might want a large depth of field (DoF). Similarly, you might have someone you want to take a photo of in front of a crowd which you are not interested in. You can isolate them from the background using a shallow DoF.
     
  5. Corvphotography

    Corvphotography TPF Noob!

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    good job from above ^
    l
     
  6. 8ball

    8ball TPF Noob!

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    very good reading in the above posts i am goign to have to play around with this

    So let me see if i get this, the lower the f stop f/2 i will be more in focus on a smaller spot where if i have a higher f stop f/22 alot more will be in fous is this right?
     
  7. AdrianC

    AdrianC TPF Noob!

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    Yeah, that's right.
     
  8. 8ball

    8ball TPF Noob!

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    now does the f stop have anythign to do with amount of light being let in or no? thats only the appature correct?
     
  9. MrBarney

    MrBarney TPF Noob!

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    The opening in the lens is the aperture
    f-stop is a measure of the size of the aperture (as a fraction)
    The size of the aperture determines how much light is let in.
     
  10. Bram

    Bram TPF Noob!

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    Woooooowwww
    Great explanation guys.
     
  11. BuS_RiDeR

    BuS_RiDeR No longer a newbie, moving up!

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    :thumbup:

    Yes!

    The aperture is the opening where light comes into the camera... The higher the number... the smaller the hole/tunnel/however you prefer to think of it...

    The Shutter speed determines how long the "curtain" stays open to allow light to go through the aperture to the film/sensor...

    And the ISO determines how sensitive the film/sensor is to light...

    Thus the holy trinity of photography is Aperture, Shutter speed, and ISO... Basicly that is. :)
     
  12. kundalini

    kundalini Been spending a lot of time on here!

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    Whoa right there sonny boy!!! The Holy Trinity of photography is Nikon's 14-24mm, 24-70mm & 70-200mm lenses. :D

    Now the Exposure Triangle of photography is aperture, shutter speed and ISO.



    Listen to MrBarney.
     

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