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Thread: Lens F number

  1. #1

    Default Lens F number

    Can anyone enlighten me on wat does the F number on the lens refers to? What the difference between the lens F number and the camera F number? Does using a Lens with a small F number = a smaller allowable F number on the camera? For example we use 50mm F1.4 len does it means that we can shot at 1.4 on the camera??

  2. #2
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    Default Re: Lens F number

    Capital F means focal length, it should be f

    The usable aperture (f) is as the glass allows, f/1.8 means it's maximum aperture is f/1.8, if f/2.8 means it's maximum aperture is f/2.8.

  3. #3

    Default Re: Lens F number

    Quote Originally Posted by espn
    Capital F means focal length, it should be f

    The usable aperture (f) is as the glass allows, f/1.8 means it's maximum aperture is f/1.8, if f/2.8 means it's maximum aperture is f/2.8.
    That means if a len is rated f4 means even i set f2.8 on my camera its also not possible??

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    Default Re: Lens F number

    Quote Originally Posted by flowerpot99
    That means if a len is rated f4 means even i set f2.8 on my camera its also not possible??
    If the glass is rated f/4, you cannot set it bigger. The glass's aperture can only open at f/4, it will notify the body it's maximum aperture is f/4. Even if you managed somehow to put it at f/2.8, the glass still only opens up to f/4.

    You can set smaller aperture values, but never larger.

  5. #5

    Default Re: Lens F number

    Quote Originally Posted by espn
    If the glass is rated f/4, you cannot set it bigger. The glass's aperture can only open at f/4, it will notify the body it's maximum aperture is f/4. Even if you managed somehow to put it at f/2.8, the glass still only opens up to f/4.

    You can set smaller aperture values, but never larger.
    Wow thanks man. Haha ESPN you like the admin here so fast reply.

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    Default Re: Lens F number

    Quote Originally Posted by flowerpot99
    Wow thanks man. Haha ESPN you like the admin here so fast reply.
    Eh, no lor. Admin faster, I just happened to be infront of PC. Cheers.

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    Default Re: Lens F number

    Quote Originally Posted by espn
    Capital F means focal length, it should be f

    The usable aperture (f) is as the glass allows,
    f (lowercase) is the focal length as well. Apertures in photography are specified by their diameter, which is usually written as a fraction of the focal length. E.g., for a f=50mm lens, f/4=12.5 mm aperture.

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