Re: Problems with Canon EF 50mm f/1.8 Lens

Discussion in 'Digital Photography' started by J?rg Preddimann, Jul 12, 2004.

  1. The Last Gunslinger <> wrote in message news:<>...
    > Hi All
    > I bought a Canon EF 50mm f/1.8 lens a couple of months ago.
    > The 'in focus' depth (dont know what this is called) appears to be about
    > 1 or 2 cm at f/1.8 at a distance of 1-2 metres.
    > Is this about right?
    > Is there any calculation to work out the 'in focus' depth?
    > Is there a technical term for the 'in focus' depth?
    >
    > The lens is attached to a 300D.
    >
    > Cheers


    This is a frequent occurance with Canon autofocus lenses. The problem
    is poor quality control and very bad sample variation. Canon
    outsources the manufacturing of its non L lenses (and the 300D CMOS)
    to sweat shops in the poorest sections of Asia. The exploitation of
    slave labor by Canon is the reason why you can buy this lense for $60
    USD. Switch to Sigma to avid this problem. Sigma makes lenses for your
    300D, but you would be better of going native and buying the much
    better Sigma SD10 body too. You will gain:

    1--a professional body with excellent lenses, & better image quality
    than anything Canon
    2--a self-cleaning Foveon sensor with 3 colour layers like film
    (instead of the grayscale, poorer version of the already poor 10D CMOS
    outsourced to sweat shops in Asia for manufacturing by slave labor)
    3--built in camera shake stoppage so you will almost never need a
    tripod.


    --

    Jörg Preddimann
     
    J?rg Preddimann, Jul 12, 2004
    #1
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  2. J?rg Preddimann

    Dave Guest

    The bizarre, off topic and biased comments notwithstanding, DOF is
    related to focal length, film/digital format, subject distance, and apeture.
    It is largely unrelated to manufacturer. You could do a google search for
    online free calculators that will give you DOF after you put in the details
    of your lens. For example,

    http://dfleming.ameranet.com/dofjs.html

    DOF is not an exact number, it relates also to human tolerance of focus
    variance. Mathematically this is repersented as a 'circle of confusion'
    correction factor.

    Dave

    "J?rg Preddimann" <> wrote in message
    news:...
    > The Last Gunslinger <> wrote in message

    news:<>...
    > > Hi All
    > > I bought a Canon EF 50mm f/1.8 lens a couple of months ago.
    > > The 'in focus' depth (dont know what this is called) appears to be about
    > > 1 or 2 cm at f/1.8 at a distance of 1-2 metres.
    > > Is this about right?
    > > Is there any calculation to work out the 'in focus' depth?
    > > Is there a technical term for the 'in focus' depth?
    > >
    > > The lens is attached to a 300D.
    > >
    > > Cheers

    >
    > This is a frequent occurance with Canon autofocus lenses. The problem
    > is poor quality control and very bad sample variation. Canon
    > outsources the manufacturing of its non L lenses (and the 300D CMOS)
    > to sweat shops in the poorest sections of Asia. The exploitation of
    > slave labor by Canon is the reason why you can buy this lense for $60
    > USD. Switch to Sigma to avid this problem. Sigma makes lenses for your
    > 300D, but you would be better of going native and buying the much
    > better Sigma SD10 body too. You will gain:
    >
    > 1--a professional body with excellent lenses, & better image quality
    > than anything Canon
    > 2--a self-cleaning Foveon sensor with 3 colour layers like film
    > (instead of the grayscale, poorer version of the already poor 10D CMOS
    > outsourced to sweat shops in Asia for manufacturing by slave labor)
    > 3--built in camera shake stoppage so you will almost never need a
    > tripod.
    >
    >
    > --
    >
    > Jörg Preddimann
     
    Dave, Jul 12, 2004
    #2
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  3. J?rg Preddimann

    DJ Guest

    Predders, you are just full of shit.
     
    DJ, Jul 12, 2004
    #3
  4. J?rg Preddimann

    Miro Guest


    >
    > DOF is not an exact number, it relates also to human tolerance of

    focus
    > variance. Mathematically this is repersented as a 'circle of confusion'
    > correction factor.


    The threshold at which an image is seen as in-focus is a precise number. The
    final judge is perceptual acuity not mathematical probability. At any given
    range an image is sharp for a given set of conditions.

    There is no need to limit the tolerance to infinite precision if the goal is
    attained.
     
    Miro, Jul 12, 2004
    #4
  5. J?rg Preddimann

    Chris Down Guest

    DJ

    What on earth do you have against shit?




    "DJ" <> wrote in message
    news:...
    > Predders, you are just full of shit.
    >
    >
     
    Chris Down, Jul 12, 2004
    #5
  6. J?rg Preddimann

    DJ Guest

    On Tue, 13 Jul 2004 03:16:07 +1000, " Miro" <> wrote:

    >
    >>
    >> DOF is not an exact number, it relates also to human tolerance of

    >focus
    >> variance. Mathematically this is repersented as a 'circle of confusion'
    >> correction factor.

    >
    >The threshold at which an image is seen as in-focus is a precise number.


    Yeah??

    The
    >final judge is perceptual acuity not mathematical probability. At any given
    >range an image is sharp for a given set of conditions.
    >
    >There is no need to limit the tolerance to infinite precision if the goal is
    >attained.
    >


    And in English ... ?
     
    DJ, Jul 13, 2004
    #6
  7. J?rg Preddimann

    DJ Guest

    On Mon, 12 Jul 2004 17:27:17 GMT, "Chris Down" <> wrote:

    >DJ
    >
    >What on earth do you have against shit?


    On reflection nothing, it makes things grow. Preddy's rantings OTOH simply
    diminish the discussions.

    >
    >
    >
    >
    >"DJ" <> wrote in message
    >news:...
    >> Predders, you are just full of shit.
    >>
    >>

    >
     
    DJ, Jul 13, 2004
    #7
  8. J?rg Preddimann

    Miro Guest

    "DJ" <> wrote in message
    news:...
    > On Tue, 13 Jul 2004 03:16:07 +1000, " Miro" <> wrote:
    >
    > >
    > >>
    > >> DOF is not an exact number, it relates also to human tolerance of

    > >focus
    > >> variance. Mathematically this is repersented as a 'circle of confusion'
    > >> correction factor.

    > >
    > >The threshold at which an image is seen as in-focus is a precise number.

    >
    > Yeah??
    >
    > The
    > >final judge is perceptual acuity not mathematical probability. At any

    given
    > >range an image is sharp for a given set of conditions.
    > >
    > >There is no need to limit the tolerance to infinite precision if the goal

    is
    > >attained.
    > >

    >
    > And in English ... ?


    What you see is what you get. You dont need an Excel spreadsheet to figure
    that out.
     
    Miro, Jul 13, 2004
    #8
  9. J?rg Preddimann

    DJ Guest

    On Tue, 13 Jul 2004 20:40:28 +1000, " Miro" <> wrote:

    >
    >"DJ" <> wrote in message
    >news:...
    >> On Tue, 13 Jul 2004 03:16:07 +1000, " Miro" <> wrote:
    >>
    >> >
    >> >>
    >> >> DOF is not an exact number, it relates also to human tolerance of
    >> >focus
    >> >> variance. Mathematically this is repersented as a 'circle of confusion'
    >> >> correction factor.
    >> >
    >> >The threshold at which an image is seen as in-focus is a precise number.

    >>
    >> Yeah??
    >>
    >> The
    >> >final judge is perceptual acuity not mathematical probability. At any

    >given
    >> >range an image is sharp for a given set of conditions.
    >> >
    >> >There is no need to limit the tolerance to infinite precision if the goal

    >is
    >> >attained.
    >> >

    >>
    >> And in English ... ?

    >
    >What you see is what you get. You dont need an Excel spreadsheet to figure
    >that out.
    >


    So you are saying "if it looks sharp it is sharp"?
     
    DJ, Jul 13, 2004
    #9
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