Summary: Memory cards is the medium that stores information in digital cameras.In the digital imaging realm, understanding how data is collected, assembled, saved and displayed is essential. That knowledge explains the relationship between memory and quality photographic images. Learn about megapixels, resolution, jpeg files, TIFF files and more from a veteran portrait photographer.

    Digital cameras rely on memory to record the images and store them until you are ready to convert the digital information into a print.  Along with the image sensor and lens quality of the camera, the memory system of your camera is as essential as fuel is to your automobile.  No gas, no drive.  No memory, no photograph.

    In successful portrait photography with a digital camera, you will need to shoot a large number of photographs of varying poses, compositions and locations.  A camera with a removable memory card is essential.  This will allow you to shoot at the highest quality level and provide for a greater number of exposures.

Types of memory cards

    Memory cards are classified into six groups.  The memory stick (MS), secure digital card (SD), multimedia card (MMC), xD picture card (xD), smartmedia (SM) and the compactflash card (CF) are manufactured under a variety of brand names. Shape, size and connection method do not allow interchangeable use. The camera manual explain in detail your camera's requirements.   
   
     Removable memory cards allow you to store images on a card and when it is full, simply insert another card to continue shooting.  The importance of a larger capacity memory card is to allow the camera to record information at the highest resolution possible and at the highest compression level to assure quality images for your photo finisher.  

    The memory card often provided with your camera by the manufacturer is likely too small to allow the kind of flexibility required for portraiture.  A good gauge of how much memory you will require for your camera is to use the megapixel rating as a benchmark. Minimum requirements follow are:

    2 megapixel camera...64 MB card
    3 megapixel camera...128 MB card
    4 megapixel camera...256 MB card
    5 megapixel camera...512 MB card
    6-10 megapixel cameras...1G card

    Capture resolution for digital cameras begins at 1280x960 for a 1 megapixel camera and can record at a 3264x2448 for a 8 megapixel camera.

A numbers game

    How many exposures you can put on a card depends on the resolution and the compression level of your camera. While the resolution of most digital cameras is fixed, the compression level can be adjusted.

    As a guide... a 4 megapixel camera equipped with a 256MB flash card, saved as a jpeg at a 1.9 compression rate, will hold about 134 images.

Pixel protection

    The compression rate for saving all of those pixels in a digital image can affect the quality of the image now and in the future.  

    JPEG compression and quality levels from fine to normal to low will result in corresponding loss of quality. The small size of the file allows you to shoot more images on your memory cards.  However, JPEG files lose data each time they are opened in a computer program.

    Saving images as a TIFF file with no compression will result in no loss of data. Those images can be opened as a computer file time and again without loss of quality.

    Some high-end and very expensive cameras allow capturing images as a RAW file that records the maximum data available.

    Keys to success:

•  Memory is essential
•  Removable memory cards are preferred
•  More megapixels equals higher resolution
•  Avoid data loss through proper file saving