Canon lenses: EF EOS USM IS WTF (made that last one up)

Discussion in 'Digital Photography' started by Rabid, Jan 21, 2004.

  1. Rabid

    Rabid Guest

    OK newbie here,

    I bought a 300D with kit lens and want a telephoto lens for it.

    I thought I'd try Ebay for a bargain (!), and straight away I found I don't
    know enough to bid.

    Is there a guide anywhere of what all the letters mean??

    And will all lenses be autofocus? even Sigma ones??

    Any help greatly appreciated.

    Rabid, Jan 21, 2004
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  2. Rabid

    Tony Spadaro Guest

    Don't get a Sigma lens, there is a good chance it will not work on your
    camera and Sigma will only re-chip for the original owner of the lens, and
    only if they deem the lens not to be too old for re-chipping - My 6 year old
    lens was "too old". Sigma is a crap company anyway.

    home of The Camera-ist's Manifesto
    The Improved Links Pages are at
    A sample chapter from my novel "Haight-Ashbury" is at
    Tony Spadaro, Jan 21, 2004
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  3. First of all check B&H- ( for lens prices,
    many lenses sell on eBay for MORE than they cost new!

    Any Canon lens marked with the letters "EF" will work on your camera.
    EF is the lens mount for the EOS line, and other than the kit lens
    (EF-S) all Canon auto-focus lenses are EF lenses.

    USM means "ultra-sonic motor". This is a special, very fast and
    quiet, lens motor to drive the auto-focus. Ring-USM motors allow you
    to manually focus a lens even in AF mode, but this does not work well
    on the 300D. Micro-USM motors are almost as fast and quiet, but do
    not allow "full time manual" focus. Most lenses use much cheaper DC
    motors. "HSM" is the Sigma designation for a similar technology.

    IS is Canon-speak for "image stabilising"- the lens has mechanical
    parts that actually move a lens element to compensate somewhat for
    motion blur and create sharper images.

    Most Sigma lenses markes as being "for Canon EOS" or some such will
    work fine on the 300D, however some older lenses may not. This is a
    software compatibility issue, and may or may not be resolved by
    sending the lens to Sigma to be "re-chipped".

    Canon's pro lenses are marked with an "L". Sigma's high-end lenses
    are marked "EX"

    In addition you will see:

    A focal length or range or focal lengths for a zoom, eg. 18mm-55mm.

    The largest aperture of the lens, may be marked as f/2.8 or 1:2.8. A
    zoom lens will usually have a range gives as f/2.8-5.6 or 1:2.8-5.6.
    The smallest aperture (e.g. f/22) is usually not marked on the lens.

    The diameter will be given, usually using the diameter symbol- a
    circle with a slash through it. The kit lens accept 58mm filters.

    Finally you may see something to identify the version of the lens, for
    example "Mark II", etc. You may also see "Macro", which means the
    lens has some (often limited) close-focussing abilities.

    Always check carefully before buying a lens, many version may exist
    and they are not always equal. There are, for example, three
    different Canon EF 75-300mm lenses on the market.
    The Black Sheep, Jan 21, 2004
  4. Rabid

    philipp Guest

    As discovered in my search of Ebay - Forget them and buy from B&H or
    local shop.

    I just ordered a new 1.8 50MM for my DRebel today. $75 over the
    counter. They will call me when it comes in - ???
    philipp, Jan 22, 2004
  5. Don't get a Sigma lens, there is a good chance it will not work on your
    Agree 100%. Smegma is garbage.
    Randall Ainsworth, Jan 22, 2004
  6. Peter,

    Some basic info for you on this. First off, if you are sifting through
    ebay, unless it is by Canon, in general look to see if it is autofocus (over
    90% will be). I am not sure how well manual focus lenses work on the
    Digital Rebel, on the Elan 7 Series there are some issues.

    Now if you want to know about a lens check the following places: This place has ratings on how sharp the lenses are. The
    higher the better (most of the time). Now they are not perfect, but so far
    they are the best for raw data. Now this place has user reviews of everything
    photographic. Check them out and see commentary. Oddly enough an english based site on a german domain.
    Well check all the basic info on just about ANY lens here. They also
    compile relevent opionons on different characteristics of each lens for some
    rather basic info.

    As to what the letters mean:


    ASP / ASL / XR / DO: Lighter glass.

    APO / LD / AD / UD: A special design that removes chomatic abberations
    (problems) from your picture.

    IF: Internal Focusing, the lens does not move when focusing.

    RF: Rear focusing, basically the same as IF.

    USM / HSM: Ultrasonic motor, a quite and fast drive system for the lens.

    L / EX / SP: The very best of that manufacturer.

    AF / EF: Autofocus.

    IS / OS: Optocal stabilized (makes photography easier when a tripod is

    FT-M: Full time manual.

    There is a quick primer.

    Good luck!

    Robert Meyers
    Robert Meyers, Jan 22, 2004
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