Why doesn't the better camera have a better dpi?

Discussion in 'Digital Photography' started by Tony Carlisle, Oct 2, 2003.

  1. I have a 4 megapixel Kodak DX4900 that delivers a nice 2448x1632 image
    at 230 dpi (according to my Photoshop). I just bought the 6.3
    megapixel Canon EOS Rebel and the high-end jpg setting delivers a very
    nice 3072x2048 image but it's only at 180 dpi.

    Why doesn't the better camera have a better dpi?


    Tony Carlisle, Oct 2, 2003
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  2. Tony Carlisle

    Bob Hatch Guest

    It does. 2448x1632 is less than 2048x3072. The dpi is just a number that is
    picked up by your software. The Kodak at 230 dpi will produce an image of
    10.643 x 7.096 inches. The Canon, if changed from 180 to 230 will produce an
    image of 13.357 by 8.904 inches. The key is total pixels that you have to
    work with.
    Bob Hatch, Oct 2, 2003
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  3. Actually, Photoshop does not specify the dpi of an image, your printer
    does that.
    Photo specifies the ppi (pixels/inch). But even that is irrevalent.
    That is just a way that PS keeps track of the math.
    If you UN check the resample box and set the width of each image to the
    same size, say 10 inches, you will notice that the Rebel image has a
    greater resolution (307 ppi) wheras the Kodak image has a resolution of
    245 ppi.
    Bob Williams
    Robert E. Williams, Oct 2, 2003
  4. Tony Carlisle

    Mark Hanson Guest

    The Canon produces a 3072x2048 pixel image, period.

    The DPI value in the file doesn't come into play until you attach
    the image to a physical medium, one with physical dimensions. At
    this time, you can change the DPI setting to whatever value you
    want, to make the print whatever size you want. 180 is just a
    default value.

    Mark Hanson, Oct 2, 2003
  5. Hi Tony
    "better dpi" is your own subjective choice. There's
    no objective "better dpi".

    The DPI out of the camera is an arbitrary choice.

    What MATTERS is that the EOS rebel is giving you
    [1] more pixels and [2] cleaner pixels. That's
    what provides the chance to make better images.

    Hope that clarifies a bit.

    Stanley Krute, Oct 2, 2003
  6. Tony Carlisle

    Tony Spadaro Guest

    Don't pay attention to the dpi -- it is an arbitrary number that only
    becomes important when printing. Your new camera has 3072 pixels where the
    old one had 2448 -- which is 624 MORE pixels in the horizontal direction
    alone. There are 2048 columns in that sensor each of which has 624 MORE
    pixels than the old camera. Furthermore there are 416 MORE columns in the
    sensor of the new camera.
    Or take an image from the first camera and convert it to the dpi of the
    second camera and you will find that your new camera makes a bigger picture.

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    Tony Spadaro, Oct 2, 2003
  7. Tony Carlisle

    Mark Herring Guest

    dpi is not a property of the camera. The SW defaults to a print size
    when the file is opened in something like PS.
    What counts with a camera is total pixels---AND a bunch of other
    things that determine the real resolution. (pixel count sets the
    **limiting** resolution)

    digital photos, more and better computers,
    and never enough time to do the projects.
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    Mark Herring, Oct 4, 2003
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