Diff. between Close-up Filters(diopters) and Telephoto Extenders

Discussion in 'Digital Photography' started by bhaskar, Aug 4, 2003.

  1. bhaskar

    bhaskar Guest

    Hi,
    Since Close-up Filters magnify the subject by factor of 1x,2x,4x etc
    and Telephoto Extenders multiply the focal length by factors of
    2x,1.5x etc.
    Don't both of these acchive the same effect ?

    I realise that I may be confusing magnification as achieved by the
    close-up lens
    versus varying (increasing) focal length length as achieved by
    Telephoto extenders.
    But isn't increasing focal length equivalent to magnifying ? Or are
    they seperate in optical terms ?If so, then in optical terms what's
    the exact difference ? What optical parameters
    change when a close-up filter is mounted or when a telephoto extender
    is mounted ?

    In what situation would one use a close-up lens and in what situation
    would
    one use a telephoto extender ?

    Also is the close-up filter in any way related to macro phtography ?

    Prosumer cameras like Powershots have macro functionality built in,
    but what
    is to be used for macro photography using a D-SLR say 10D ?
    Can the Canon 28-135MM IS USM lens be somehow used for macro
    photography or do
    I need special macro lenses ?

    And lastly is a close-up filter kit just a poor man's macro lens ?
    and is a tele photo extender a poor man's Super Tele (focal length >
    300) Lens ?

    Thanks in advance for all those who help out,
    Just a confused newbie.
    bhaskar
    bhaskar, Aug 4, 2003
    #1
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  2. Telephoto extenders allow say a 100mm lens to function like a slower,
    less sharp 140 mm lens. Things will appear to be 1.4 times closer. So
    something 14 feet away will look like something 10 feet away

    A Close up filter will not make the subject look closer. What it means
    is that something that you might be able to photograph at 18 inches and
    resulting in a small object occupying less than 10% of the photo area, can
    be photographed at 10 inches and still be in focus.

    Tele extenders make it look like you were closer and close-up filters
    let you get closer. Not exactly the same thing.

    All else being equal the close-up filter/lens (they are really
    supplementary lenses) will give better overall sharpness when photographing
    something that is to small to photograph properly at the minimum distance
    your lens will focus.

    --
    Joseph E. Meehan

    26 + 6 = 1 It's Irish Math


    "bhaskar" <> wrote in message
    news:...
    > Hi,
    > Since Close-up Filters magnify the subject by factor of 1x,2x,4x etc
    > and Telephoto Extenders multiply the focal length by factors of
    > 2x,1.5x etc.
    > Don't both of these acchive the same effect ?
    >
    > I realise that I may be confusing magnification as achieved by the
    > close-up lens
    > versus varying (increasing) focal length length as achieved by
    > Telephoto extenders.
    > But isn't increasing focal length equivalent to magnifying ? Or are
    > they seperate in optical terms ?If so, then in optical terms what's
    > the exact difference ? What optical parameters
    > change when a close-up filter is mounted or when a telephoto extender
    > is mounted ?
    >
    > In what situation would one use a close-up lens and in what situation
    > would
    > one use a telephoto extender ?
    >
    > Also is the close-up filter in any way related to macro phtography ?
    >
    > Prosumer cameras like Powershots have macro functionality built in,
    > but what
    > is to be used for macro photography using a D-SLR say 10D ?
    > Can the Canon 28-135MM IS USM lens be somehow used for macro
    > photography or do
    > I need special macro lenses ?
    >
    > And lastly is a close-up filter kit just a poor man's macro lens ?
    > and is a tele photo extender a poor man's Super Tele (focal length >
    > 300) Lens ?
    >
    > Thanks in advance for all those who help out,
    > Just a confused newbie.
    > bhaskar
    Joseph Meehan, Aug 4, 2003
    #2
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