USM lenses

Discussion in 'Beyond the Basics' started by Camper Dave, May 7, 2004.

  1. Camper Dave

    Camper Dave TPF Noob!

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    hi folks,

    my first post! :D

    bit of anewbie question this, but what's the difference between a USM and a non USM lens? and what does it stand for? i'm looking at a new telephoto lens for my camera and it's become a bit of a sticking point.

    thanks in advance
    dave :)

    p.s. nice site!
     
  2. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    USM --> Ultra Sonic Motor. It's the motor that moves the elements to focus the lens.

    USM is great feature to have on a lens. The focus is quicker and much quieter.

    Non-USM lenses, I think they use gears to focus.

    Also, I think (but I'm not sure) that with USM lenses you can simply turn the focus ring to manually focus...while with Non-USM you have to flick a switch before you can use the focus ring.
     
  3. Camper Dave

    Camper Dave TPF Noob!

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    cheers dude :)

    think i might drift toward the USM one then if it's a quicker focus.

    thanks again,
    dave
     
  4. markc

    markc TPF Noob!

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    Canon was a bit deceptive with this, though. Not all USM motors are equal. The ring USM lenses are the ones that are the quickest and the quietest.
     
  5. Camper Dave

    Camper Dave TPF Noob!

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    cheers for that marc, it's a canon i've got. i'll have to keep an eye on that when looking. seems a bit sly selling two different 'types' under one name.
     

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