Results 1 to 7 of 7

Thread: USM and non-USM ???

  1. #1

    Default USM and non-USM ???

    need help here.

    May i know is that much different between a USM lens and a non-USM lens?
    'EF 75-300mm f/4-5.6 III USM' and 'EF 75-300mm f/4-5.6 III'....

  2. #2
    Senior Member Kit's Avatar
    Join Date
    Jan 2002
    Location
    Upper Bukit Timah
    Posts
    11,650

    Default Re: USM and non-USM ???

    Focus faster, quieter.

  3. #3
    Senior Member zac08's Avatar
    Join Date
    Feb 2005
    Location
    East
    Posts
    11,755

    Default Re: USM and non-USM ???

    USM = Ultra Sonic Motor.

    Without the USM, it'll just be the camera's focusing motor to drive the focusing unit.
    Michael Lim
    My Flickr Site

  4. #4

    Default Re: USM and non-USM ???

    oh ok thanks

  5. #5
    Member
    Join Date
    Nov 2006
    Location
    Toa Payoh
    Posts
    158

    Default Re: USM and non-USM ???

    Quote Originally Posted by zac08 View Post
    USM = Ultra Sonic Motor.

    Without the USM, it'll just be the camera's focusing motor to drive the focusing unit.
    Actually, Canon EOS cameras does not have focusing motor built in. Lens not specified with USM are fitted with ARC motor (the normal electric motor with some gears) to drive the focusing ring.
    Canon 20D,400D,5QD | 17-40mm F4L | 50 f1.8 |100 f2 | 200 f2.8L | 70-210 f3.5-4.5 | 580EX

  6. #6
    Senior Member zac08's Avatar
    Join Date
    Feb 2005
    Location
    East
    Posts
    11,755

    Default Re: USM and non-USM ???

    Quote Originally Posted by LancerCK View Post
    Actually, Canon EOS cameras does not have focusing motor built in. Lens not specified with USM are fitted with ARC motor (the normal electric motor with some gears) to drive the focusing ring.
    Oic, thanks for the clarification.
    Michael Lim
    My Flickr Site

  7. #7
    Member
    Join Date
    Nov 2006
    Location
    Toa Payoh
    Posts
    158

    Default Re: USM and non-USM ???

    Quote Originally Posted by zac08 View Post
    Oic, thanks for the clarification.
    No problem o. That's what online forums are for--to share info
    Canon 20D,400D,5QD | 17-40mm F4L | 50 f1.8 |100 f2 | 200 f2.8L | 70-210 f3.5-4.5 | 580EX

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •