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Thread: Basic question about fast/slow lens

  1. #1

    Default Basic question about fast/slow lens

    Why call a lens with a small maximum aperture a slow lens? Why call a f/1.4 lens a fast lens? It doens't make sense to me. Aperture has nothing to do with speed right? Isn't aperture just the size of the hole that lets light in? The shutter speed is controlled by the body of the camera.

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    Default Re: Basic question about fast/slow lens

    Quote Originally Posted by red_ryder
    Why call a lens with a small maximum aperture a slow lens? Why call a f/1.4 lens a fast lens? It doens't make sense to me. Aperture has nothing to do with speed right? Isn't aperture just the size of the hole that lets light in? The shutter speed is controlled by the body of the camera.
    Aperture bigger more light goes in ? So shutter speed will be faster when compared to a lens with smaller aperture ?
    Eg. 135 F2 shoot at 1/100 while 135 F4 will be at 1/25 in the same lightning conditions ?
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    Default Re: Basic question about fast/slow lens

    Quote Originally Posted by red_ryder
    Why call a lens with a small maximum aperture a slow lens? Why call a f/1.4 lens a fast lens? It doens't make sense to me. Aperture has nothing to do with speed right? Isn't aperture just the size of the hole that lets light in? The shutter speed is controlled by the body of the camera.
    Haha...

    Many possible analogy and explanation through times....

    Imagine a boat with a large hole.....and a boat with smaller hole....which sinks faster...?

    In the photography sense which will allow more light in a particular shutter open/close instance...? obviously alens with a larger aperture.

    Also as mentioned...allowing faster shutter speeds given the requirement of "desired exposure"...not changing ISO...

    rgds,
    sulhan

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    Default Re: Basic question about fast/slow lens

    ditto the above and also the fast lens makes your money disappear faster as well

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    Default Re: Basic question about fast/slow lens

    Quote Originally Posted by ortega
    ditto the above and also the fast lens makes your money disappear faster as well
    Not really.. a 50mm f1.8 is a fast lens..
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    Default Re: Basic question about fast/slow lens

    but the faster one?

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    Default Re: Basic question about fast/slow lens

    is there anything regarding sharpness of the pic if we snap by using lens with aperture below 1.8?

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    Moderator ortega's Avatar
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    Default Re: Basic question about fast/slow lens

    less dof

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    Default Re: Basic question about fast/slow lens

    Quote Originally Posted by ortega
    ditto the above and also the fast lens makes your money disappear faster as well
    *choke* *cough* erhum haha easy ortega dun scare away potential buyers haha they help us to bring prices down

  10. #10

    Default Re: Basic question about fast/slow lens

    Quote Originally Posted by majere2sg
    Not really.. a 50mm f1.8 is a fast lens..
    For a 50mm no. 50mm f/1.0 is fast.

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    Default Re: Basic question about fast/slow lens

    Quote Originally Posted by litefoot
    For a 50mm no. 50mm f/1.0 is fast.
    no no.. 50mm f1.8 is fast.. 1.4 is faster.. 1.0 is fastest
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  12. #12

    Default Re: Basic question about fast/slow lens

    Oh another thing, you need to fast a lot inorder to buy "fast" lenses.

  13. #13

    Default Re: Basic question about fast/slow lens

    Quote Originally Posted by majere2sg
    no no.. 50mm f1.8 is fast.. 1.4 is faster.. 1.0 is fastest
    No, No,...

    0.95 is the fastest of the fastest!

  14. #14

    Default Re: Basic question about fast/slow lens

    Quote Originally Posted by student
    No, No,...

    0.95 is the fastest of the fastest!
    What makes 1.2? Fasterer?

  15. #15

    Default Re: Basic question about fast/slow lens

    Quote Originally Posted by litefoot
    What makes 1.2? Fasterer?
    what is "Fasterer"?
    deadpoet
    my portfolio

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    Default Re: Basic question about fast/slow lens

    f1.8 is fast
    f1.4 is faster
    f1.2 is faster-er
    f1.0 is fastest
    f0.95 is the fastest of the fastest

    all know your lenses here... but all fail your england!!!

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    Default Re: Basic question about fast/slow lens

    Quote Originally Posted by red_ryder
    Why call a lens with a small maximum aperture a slow lens? Why call a f/1.4 lens a fast lens? It doens't make sense to me. Aperture has nothing to do with speed right? Isn't aperture just the size of the hole that lets light in?
    You're absolutely correct. "Fast lens" is slang, but unfortunately in common use.

    [QUOET]The shutter speed is controlled by the body of the camera.[/QUOTE]

    "Shutter speed" is another of these expressions. With a few exceptions, the parts of a mechanical shutter move at a speed that is independent of exposure time. Exposure time is controlled by a variable delay between the shutter opening and closing process, not by the speed (velocity).

    To make the trinity complete, the term "film speed" is obviously also nonsense.

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