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Thread: Help, please!: Canon 15-85mm IS USM or Canon 18-200mm?

  1. #21
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    Re: Help, please!: Canon 15-85mm IS USM or Canon 18-200mm?



    Quote Originally Posted by Sheiky
    By the way isn't this just a marketing trick/scam and officially illegal?

    I dunno. I do know that Apple does the same thing -- their 16GB iPhones really have a capacity of 13.7 GB, their 32GB iPhones a capacity of 28GB, etc.

  2. #22
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    Re: Help, please!: Canon 15-85mm IS USM or Canon 18-200mm?



    Well every hard-disk or other storage system has that, even on windows pc's. I believe it has something to do with computers seeing 1GB as 1024MB (bits-system) and the product makers state it as 1000MB(decimal system). So if you'd buy a 750GB HDD, devide it by 1.024 and you'll end up with what your PC makes of it...(or something like that [:P])


    But focal length is not touched by any mathematic system or something. It's pure physics right? 200mm focal length "IS" 200 focal length. Got to dig that stuff back up before I can explain it [:P]



  3. #23
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    Re: Help, please!: Canon 15-85mm IS USM or Canon 18-200mm?



    Interesting comparison. I did some shooting this weekend, and the EXIFs
    for 200mm shots came up as 200mm. Go figure.


    Having such a broad range of lenses to choose from is at the same time a blessing and a curse!

  4. #24
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    Re: Help, please!: Canon 15-85mm IS USM or Canon 18-200mm?



    Quote Originally Posted by lynx
    Interesting comparison. I did some shooting this weekend, and the EXIFs
    for 200mm shots came up as 200mm. Go figure.

    I would say you're getting scammed! [A]


    Quote Originally Posted by lynx
    Having such a broad range of lenses to choose from is at the same time a blessing and a curse!

    If you're aware of the abilities of a broad range it's definitely an advantage! It's only a curse if something different happens that you didn't expect to happen []

  5. #25
    Senior Member neuroanatomist's Avatar
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    Re: Help, please!: Canon 15-85mm IS USM or Canon 18-200mm?



    Quote Originally Posted by Sheiky
    Does your exif with the 18-200 still say 200mm?

    EXIF with both says 200mm.


    Quote Originally Posted by Sheiky
    Considering the 135mm of the 18-135 is really 135mm

    True - I almost added that statement to my post. Bryan's review of the 18-135mm doesn't mention anything odd about the long end, and the focal length comparisons shot that 135mm is a lot tighter than 87mm.


    Quote Originally Posted by Sheiky
    By the way isn't this just a marketing trick/scam and officially illegal? ...focal length is not touched by any mathematic system or something. It's pure physics right? 200mm focal length "IS" 200 focal length.

    I doubt it. For a camera lens, focal length is the distance from the nodal point of the lens to the sensor/film. For the EF-S 18-200mm @ 200mm, that distance will be 200mm as calculated by Canon's engineers (depending on lens elements, the nodal point can be well forward of the front element the lens). The relationship of focal length to angle of view makes several assumptions (e.g. perfectly rectilinear and no distortions). Presumably because of distortions in the lens, the angle of view for the 18-200mm @ 200mm is wider than for other lenses at that same focal length.



    <div>


    Quote Originally Posted by Sheiky


    Quote Originally Posted by lynx
    Having such a broad range of lenses to choose from is at the same time a blessing and a curse!

    If you're aware of the abilities of a broad range it's definitely an advantage! It's only a curse if something different happens that you didn't expect to happen

    <div>Is it considered a curse if I have a sore back after carrying them all around for a day? [:P]</div>
    </div>



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