Typo in Canon lens specs?

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

  1. Chris Carlen

    Chris Carlen Guest

    Hi:

    Their EF 28-200mm f/3.5-5.6 USM lens shows a maximum "diagonal angle of
    view" of 75 degrees.

    But the EF-S 18-55mm f/3.5-5.6 lens also shows a maximum diagonal angle
    of view of 75 degrees. I would think it must be wider than this.

    As another reference point, the EF 17-40mm f/4L USM has 104° max.

    What is the real max angle for the 18mm?

    Thanks.
    --
    _____________________
    Christopher R. Carlen

    Suse 8.1 Linux 2.4.19
     
    Chris Carlen, Sep 19, 2003
    #1
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  2. Chris Carlen wrote:
    >
    > Hi:
    >
    > Their EF 28-200mm f/3.5-5.6 USM lens shows a maximum "diagonal angle of
    > view" of 75 degrees.
    >
    > But the EF-S 18-55mm f/3.5-5.6 lens also shows a maximum diagonal angle
    > of view of 75 degrees. I would think it must be wider than this.
    >
    > As another reference point, the EF 17-40mm f/4L USM has 104° max.
    >
    > What is the real max angle for the 18mm?


    The crop factor for the Digital Rebel body is 1.6. Thus the
    35mm-equivalent focal length, at the wide end, of the 18-55 on a digital
    body is 18 x 1.6 = 28.8. So logically, it should even be slightly *less*.

    ---
    jouni maho
     
    Jouni Filip Maho, Sep 19, 2003
    #2
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  3. Chris Carlen

    Todd Walker Guest

    In article <>,
    says...
    > Hi:
    >
    > Their EF 28-200mm f/3.5-5.6 USM lens shows a maximum "diagonal angle of
    > view" of 75 degrees.
    >
    > But the EF-S 18-55mm f/3.5-5.6 lens also shows a maximum diagonal angle
    > of view of 75 degrees. I would think it must be wider than this.
    >
    > As another reference point, the EF 17-40mm f/4L USM has 104° max.
    >
    > What is the real max angle for the 18mm?
    >
    > Thanks.
    >


    Well, this is just a guess but the 18-55 only fits one camera -- the
    300D. If you consider the 1.6x focal length multiplier, the 18 mm wide
    end becomes 28.8 mm. The specs for the EF 28-200 are no doubt given
    based on its actual widest focal length of 28 mm. Therefore, the angle
    of view for both lenses would be the same, if you are using the 28-200
    on a film SLR and the 18-55 on the 300D, the only camera it will fit on.
    Of course if you put the 28-200 on the 300D it becomes a 45-320...

    --
    ________________________________
    Todd Walker
    http://twalker.d2g.com
    Canon 10D:
    http://twalker.d2g.com/canon10d
    My Digital Photography Weblog:
    http://twalker.d2g.com/dpblog.htm
    _________________________________
     
    Todd Walker, Sep 19, 2003
    #3
  4. Chris Carlen <> writes:

    >Their EF 28-200mm f/3.5-5.6 USM lens shows a maximum "diagonal angle of
    >view" of 75 degrees.


    Over the 43 mm diagonal of a 35 mm frame.

    >But the EF-S 18-55mm f/3.5-5.6 lens also shows a maximum diagonal angle
    >of view of 75 degrees. I would think it must be wider than this.


    This is over the approximately 27 mm diagonal of the 300D sensor. Since
    18:27 is the same ratio as 28:43, the field of view is the same.

    >As another reference point, the EF 17-40mm f/4L USM has 104° max.


    That's a 17 mm focal length, on an image diagonal of 43 mm.

    >What is the real max angle for the 18mm?


    You pick the diagonal, we can tell you how to calculate the max angle.
    But the lens is *designed* for the 300D sensor diagonal, and probably
    loses image quality and illumination once you get very far outside
    that.

    Dave
     
    Dave Martindale, Sep 19, 2003
    #4
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