formula to figure # of photos on card

Discussion in 'Digital Photography' started by Lobo, Apr 3, 2006.

  1. Lobo

    Lobo Guest

    Would someone please give me the formula you use to figure out how many
    digital photos you can get on a memory card? I know it has to do with the
    camera's pixel whatever-you-call-it. TIA.
    ~~~~~~~~~~~~~~~~~~~
    Delete the obvious to reply to me personally.
    ~~~~~~~~~~~~~~~~~~~
     
    Lobo, Apr 3, 2006
    #1
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  2. On Sun, 2 Apr 2006 19:42:34 -0600, Lobo <> wrote:
    > Would someone please give me the formula you use to figure out how many
    > digital photos you can get on a memory card? I know it has to do with the
    > camera's pixel whatever-you-call-it. TIA.


    There's no hard and fast rule; it depends on several things. Most
    importantly, what type of file are you saving (JPG, RAW, RAW + JPG,
    TIFF). If you're using JPG, then it depends on the level of compression
    (sometimes called "image quality" or somesuch in the camera menus) and
    also the content of your photos (simplifying somewhat, more
    detail=bigger files)

    For JPGs, a reasonable rule of thumb seems to be
    (file size in MB) = (# of megapixels)*(0.2-0.5)
    where the value of the multiplier depends on the quality setting and
    what exactly you are photographing.

    -dms
     
    Daniel Silevitch, Apr 3, 2006
    #2
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  3. Lobo

    Paul J Gans Guest

    Lobo <> wrote:
    >Would someone please give me the formula you use to figure out how many
    >digital photos you can get on a memory card? I know it has to do with the
    >camera's pixel whatever-you-call-it. TIA.


    That's hard. If you shoot JPGs, the size of each file will
    vary depending on (among other things) the subject matter.

    On my Canon 300D at one particular JPG setting, files can
    vary from about 2.8 Mbytes to about 4 Mbytes in size.

    ----- Paul J. Gans
     
    Paul J Gans, Apr 3, 2006
    #3
  4. Lobo

    Lobo Guest

    "Paul J Gans" <> wrote in message
    news:e0q0sr$55n$...
    > Lobo <> wrote:
    >>Would someone please give me the formula you use to figure out how many
    >>digital photos you can get on a memory card? I know it has to do with the
    >>camera's pixel whatever-you-call-it. TIA.

    >
    > That's hard. If you shoot JPGs, the size of each file will
    > vary depending on (among other things) the subject matter.
    >
    > On my Canon 300D at one particular JPG setting, files can
    > vary from about 2.8 Mbytes to about 4 Mbytes in size.
    >
    > ----- Paul J. Gans


    ok ... to make it simpler ... let's say 6 mega pixel camera and every photo
    is a .jpg at 2816 x 2112 pixels.
    ~~~~~~~~~~~~~~~~~~~
    Delete the obvious to reply to me personally.
    ~~~~~~~~~~~~~~~~~~~
     
    Lobo, Apr 3, 2006
    #4
  5. Lobo <> wrote:

    : ok ... to make it simpler ... let's say 6 mega pixel camera and every
    : photo is a .jpg at 2816 x 2112 pixels.

    As was said before this is the most variable setting. Jpeg compression
    (among other things) reduces the storage space required for large areas of
    the same color by doing something like storing "color=xx, repete xxx
    times" (highly simplified explaination). So if you take a photo that is
    all one color/intensity/etc the file would compress very well and be very
    tiny. While an image with the same camera, with the same settings but of
    an image with every single pixel being a very different value, there would
    be nearly no compression and be about the same as a RAW file. Most normal
    images will be something inbetween.

    My rule of thumb is that the number that the camera reports when you put
    in a new card will be one end of the probable range while double that
    number would be the other end. The actual capacity for that card with the
    particular images you take will fall somewhere in the middle. For example,
    when I am taking pictures of fireworks where the background is almost all
    black sky I can regularly get nearly double the basic capacity on the
    card. But daytime scenic photos with lots of contrasting details the
    capacity of the card will be nearly what the camera reported originally.

    Sorry I can't give you a hard and fast math based capacity specification.
    But this is one of the "features" of compressing image files. :)

    Randy

    ==========
    Randy Berbaum
    Champaign, IL
     
    Randy Berbaum, Apr 3, 2006
    #5
  6. Lobo

    Paul Allen Guest

    Lobo wrote:
    > "Paul J Gans" <> wrote in message
    > news:e0q0sr$55n$...
    >> Lobo <> wrote:
    >>> Would someone please give me the formula you use to figure out how many
    >>> digital photos you can get on a memory card? I know it has to do with the
    >>> camera's pixel whatever-you-call-it. TIA.

    >> That's hard. If you shoot JPGs, the size of each file will
    >> vary depending on (among other things) the subject matter.
    >>
    >> On my Canon 300D at one particular JPG setting, files can
    >> vary from about 2.8 Mbytes to about 4 Mbytes in size.
    >>
    >> ----- Paul J. Gans

    >
    > ok ... to make it simpler ... let's say 6 mega pixel camera and every photo
    > is a .jpg at 2816 x 2112 pixels.


    Not enough data. Extrapolating from my 2Mp camera at the quality
    setting I normally use, your hypothetical camera might make JPEG's
    averaging about 1.5MB. But that doesn't answer your question, since
    I don't know what quality setting you're using, or what your particular
    camera does with that setting.

    There is no formula that someone can give you that's just based on
    pixel count. The good news is that you can take a few pictures and
    have a pretty good basis for working out your own formula.

    Paul Allen
     
    Paul Allen, Apr 3, 2006
    #6
  7. Lobo

    Bob Williams Guest

    Lobo wrote:

    > Would someone please give me the formula you use to figure out how many
    > digital photos you can get on a memory card? I know it has to do with the
    > camera's pixel whatever-you-call-it. TIA.
    > ~~~~~~~~~~~~~~~~~~~
    > Delete the obvious to reply to me personally.
    > ~~~~~~~~~~~~~~~~~~~
    >
    >

    There is no formula, only educated guesses.
    As others have stated, it depends on four things:
    1) Image size e.g., 2816 x2112 pixels
    2) Format in which the image is saved, e.g., jpeg, tiff, raw etc.
    Lets assume .jpeg.
    3) Degree of compression. Usually three options, e.g. Good, Better or

    Best or something equivalent.
    4) Amount of detail in the image
    You get to choose the first three options.
    Once you do this, the camera itself will make an educated guess as to
    how many pictures your memory card will hold. This number is usually
    prominently displayed on your viewing screen. The number is updated
    after each picture. The closer you get to the end of your card the more
    accurate is your estimate.
    Bob Williams
     
    Bob Williams, Apr 3, 2006
    #7
  8. Lobo

    Mark² Guest

    Lobo wrote:
    > "Paul J Gans" <> wrote in message
    > news:e0q0sr$55n$...
    >> Lobo <> wrote:
    >>> Would someone please give me the formula you use to figure out how
    >>> many digital photos you can get on a memory card? I know it has to
    >>> do with the camera's pixel whatever-you-call-it. TIA.

    >>
    >> That's hard. If you shoot JPGs, the size of each file will
    >> vary depending on (among other things) the subject matter.
    >>
    >> On my Canon 300D at one particular JPG setting, files can
    >> vary from about 2.8 Mbytes to about 4 Mbytes in size.
    >>
    >> ----- Paul J. Gans

    >
    > ok ... to make it simpler ... let's say 6 mega pixel camera and
    > every photo is a .jpg at 2816 x 2112 pixels.
    > ~~~~~~~~~~~~~~~~~~~
    > Delete the obvious to reply to me personally.
    > ~~~~~~~~~~~~~~~~~~~


    It is quite variable with jpeg files.
    Here's an example:
    Two images on my computer...shot back-to-back with identical settings, pixel
    dimensions, etc....
    One is 2,260 KB, and the other is 1,494 KB.
    The ONLY difference between them is the colors and patterns found within the
    scene/subject matter.
    The smaller size is due to simpler image attrrbutes, which allows larger
    fields within the image to be more highly compressed.

    So... There is no hard and fast formula for jpeg files.

    An easy demonstration of this is to take a picture of a piece of one-color
    paper (like yellow or blue or white).
    Now take a picture of a complicated scene with many colors and lined
    patterns, shapes, etc.
    Compare teh two file sizes on your computer, and you'll soon see why there's
    no simple answer.
     
    Mark², Apr 3, 2006
    #8
  9. Lobo

    Paul J Gans Guest

    Paul Allen <"paul dot l dot allen at comcast dot net"> wrote:
    >Lobo wrote:
    >> "Paul J Gans" <> wrote in message
    >> news:e0q0sr$55n$...
    >>> Lobo <> wrote:
    >>>> Would someone please give me the formula you use to figure out how many
    >>>> digital photos you can get on a memory card? I know it has to do with the
    >>>> camera's pixel whatever-you-call-it. TIA.
    >>> That's hard. If you shoot JPGs, the size of each file will
    >>> vary depending on (among other things) the subject matter.
    >>>
    >>> On my Canon 300D at one particular JPG setting, files can
    >>> vary from about 2.8 Mbytes to about 4 Mbytes in size.
    >>>
    >>> ----- Paul J. Gans

    >>
    >> ok ... to make it simpler ... let's say 6 mega pixel camera and every photo
    >> is a .jpg at 2816 x 2112 pixels.


    >Not enough data. Extrapolating from my 2Mp camera at the quality
    >setting I normally use, your hypothetical camera might make JPEG's
    >averaging about 1.5MB. But that doesn't answer your question, since
    >I don't know what quality setting you're using, or what your particular
    >camera does with that setting.


    >There is no formula that someone can give you that's just based on
    >pixel count. The good news is that you can take a few pictures and
    >have a pretty good basis for working out your own formula.


    >Paul Allen


    And, as I said, space needs can vary greatly from picture to picture.

    ---- Paul J. Gans
     
    Paul J Gans, Apr 4, 2006
    #9
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