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Millimeters?

  • 29-10-2005 4:24pm
    #1
    Oriel
    Banned (with Prison Access) Posts: 5,154 ✭✭✭


    Ok,
    If a lens has a limit of, say 70mm to 370mm, what exactly is the measurement of? What is 37cm?

    S.


Comments

  • #2
    PurpleFistMixer
    Registered Users, Registered Users 2 Posts: 5,851 ✭✭✭PurpleFistMixer


    As far as I can recall, mm is a measurement of the focal length. Ie, the distance from the lens (though I'm not sure what PART of the lens) to the sensor/film. Lenses don't actually get 37cm long, though, (well some do, but not most typical ones) so that length is made up using mirrors and such.


  • #3
    Oriel
    Banned (with Prison Access) Posts: 5,154 ✭✭✭Oriel


    I thought it had maybe something to do with the difference between the distance between lens and sensor, but then I think the mirror thing sounded a bit to impractical.


  • #4
    FX Meister
    Closed Accounts Posts: 5,217 ✭✭✭FX Meister


    It is the distance from the primary element of the lens to the film plane/sensor. It determines the magnification and view angle of the lens. For a given lens, a longer focal length will produce greater magnification and a smaller view angle.


  • #5
    PurpleFistMixer
    Registered Users, Registered Users 2 Posts: 5,851 ✭✭✭PurpleFistMixer


    The mirror thing is quite practical. It lets you have a shorter and lighter lens with only minimal quality loss. Otherwise everyone would be lugging around massive big lenses.


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