Why is EF17-40mm f/4L USM so expensive?

Discussion in 'Digital Cameras' started by Chris Carlen, Sep 19, 2003.

  1. Chris Carlen

    Chris Carlen Guest

    Hi:

    Compared to the EF-S 18-55mm f/3.5-5.6, that is. I see prices of over
    $700 for the USM lens, compared to the EOS300D kit lens which we know is
    about $100.

    I've looked at the specs, but I just see why the 17-40mm is so much
    more. They have the same focussing distances, but the EF-S is much
    lighter. Of course the 17-40mm is a little more wide angle, but it also
    doesn't go as far into the long end. I suppose the fact that the
    17-40mm keeps f/4.0 at all focal lengths is worth something, but I'm not
    sure that it's so valuable as to warrant a factor of 7 in price.

    I'm new at this and considering buying an EOS300D, so I am eager to
    learn. I will be interested to hear why these lenses are valued so
    differently. I'm looking at options for replacing the kit lens with
    something of at least the same wide angle range, but perhaps a little
    faster, but the options are way too expensive. I would consider
    something in the $300-$500 range maybe, but whew! lenses can be very
    pricey $$$.

    Ooh, I see the 17-40mm has a lot of exotic optics, with three aspheres
    and a UD. Is that it?

    Thanks.
     
    Chris Carlen, Sep 19, 2003
    #1
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  2. Yes. It's an "L" series lens (assuming you've given the model
    designation correctly; but it fits the price issue and the exotic
    optics), which are Canon's top-grade ("pro series") lenses.

    What's worth what is up to you; and depends on your uses. I'm not a
    professional; my camera spends most of its time in the bag. I haven't
    faced this exact decision, since I'm a Nikon user rather than a Canon
    user, but my zooms are all third-party, not Nikor. I even own a Sigma
    lens (105mm macro).
     
    David Dyer-Bennet, Sep 19, 2003
    #2
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  3. The big difference is angular coverage. The 17-40 mm covers an image
    circle of about 43 mm, the diagonal of a 35 mm frame. This gives it a
    very wide field of view in subject space - 104 degrees if we ignore
    any distirtion. It takes a complex design to cover that extreme field
    of view.

    The 18-55 only covers the diagonal of the 300D sensor, about 27 mm.
    This gives an angle of view of about 74 degrees, which is easier to deal
    with. The lens is smaller and cheaper as a result.

    In fact, the field of view of the 18-55 is the same as a 29-88 mm lens
    (approximately) on a 35 mm camera. So all you need is the same number
    of elements, more or less, as a 28-90 zoom for a 35 camera. In fact,
    if you took a 28-90 zoom design and reduced all the dimensions by a
    factor of 1.6, you'd get a 18-55 mm zoom that covers a 27 mm circle.
    It would be considerably smaller and lighter than the 28-90 because of
    the reduced volume of glass (by a factor of 1.6^3), and have a shorter
    back focus (which the EF-S mount can handle).

    Dave
     
    Dave Martindale, Sep 19, 2003
    #3
  4. I haven't seen the 18-55 yet, but my understanding is that it's very
    similar in design and construction to the 22-55/4-5.6 that was the kit
    lens with the EOS IX Lite body. I have one of the latter, bought it
    used for $40, and after not using it for a very long time I popped it
    on the 10D last night.

    Yuck. Compared to my other Canon lenses, it's just very mediocre
    quality, in every respect. I now think it wasn't really worth $40.

    Godfrey
     
    Godfrey DiGiorgi, Sep 19, 2003
    #4
  5. Chris Carlen

    Chris Carlen Guest

    [edit]


    Thanks to all who responded.
     
    Chris Carlen, Sep 19, 2003
    #5
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